Zurich Open Repository andArchiveUniversity of ZurichMain LibraryStrickhofstrasse 39CH-8057 Zurichwww.zora.uzh.ch

Year: 2019

A new fossil-Lagerstätte from the Late Devonian of Morocco : faunalcomposition, taphonomy and paleoecology

Frey, Linda

Posted at the Zurich Open Repository and Archive, University of ZurichZORA URL: https://doi.org/10.5167/uzh-177848DissertationPublished Version

Originally published at:Frey, Linda. A new fossil-Lagerstätte from the Late Devonian of Morocco : faunal composition, taphon-omy and paleoecology. 2019, University of Zurich, Faculty of Science.

A New Fossil-Lagerstätte from the Late Devonian of Morocco: Faunal

Composition, Taphonomy and Palaeoecology Dissertation

zur

Erlangung der naturwissenschaftlichen Doktorwürde (Dr. sc. nat.)

vorgelegt der

Mathematisch-naturwissenschaftlichen Fakultät

der

Universität Zürich

von Linda Frey

von

St. Ursen FR

Promotionskommission

Prof. Dr. Christian Klug (Leitung der Dissertation) Prof. Dr. Hugo Bucher Prof. Dr. Marcelo Sánchez

Prof. Dr. Michael Coates

Dr. Martin Rücklin

Zürich, 2019

ABSTRACT ................................................................................................................................................2

INTRODUCTION......................................................................................................................................5

CHAPTER I Late Devonian and Early Carboniferous alpha diversity, ecospace occupation,

vertebrate assemblages and bio-events of southeastern Morocco ..............................27

CHAPTER II Fossil-Lagerstätten and preservation of invertebrates and vertebrates from the

Devonian in the eastern Anti-Atlas (Morocco) ...........................................................61

CHAPTER III Morphology, phylogenetic relationships and ecomorphology of the early

elasmobranch Phoebodus ............................................................................................89

CHAPTER IV Functional morphology of mandibular arches in symmoriids as exemplifi ed

by Ferromirum oukherbouchi gen. et sp. nov. (Late Devonian) ...............................135

CONCLUSIONS ....................................................................................................................................167

APPENDIX

Appendix A Collaboration with other projects (abstracts) ............................................................171

Appendix B Additional article published during doctoral studies ................................................175

ACKNOWLEDGEMENTS ..................................................................................................................203

CURRICULUM VITAE ........................................................................................................................207

2

Abstract

The Late Devonian (382. 7 to 358.9 Ma) was a period of intense environmental perturbations and fun-damental changes in marine ecosystems impacting also the marine vertebrates. Two extinction events, namely the Kellwasser Event (Frasnian-Famennian boundary) and the Hangenberg Crisis (latest Devoni-an) caused severe losses in diversity. Especially several groups of gnathostomes were strongly affected by the Hangenberg Crisis, which represents a bottleneck in the evolutionary history of jawed vertebrates. The marine ecosystem became reshaped and the previously diverse placoderms went extinct and the taxonomic diversity of acanthodians decreased, while other chondrichthyans and osteichthyans diversifi ed. From the stratigraphic interval between the Kellwasser and the Hangenberg crises, well-preserved remains of plac-oderms and isolated teeth were well documented from Morocco before. By contrast, articulated remains of chondrichthyans were discovered only recently from the Famennian of the Maïder region (Morocco) within this PhD project. Most fossil fi sh were found in a stratigraphic interval with abundant remains of thylacocephalan arthropods preserved in ferruginous nodules (early/ middle Famennian Thylacocephalan Layer). These gnathostomes include both known and new taxa of sarcopterygians (onychodontids), plac-oderms (Dunkleosteus, Titanichthys, Alienacanthus and Driscollaspis) and chondrichthyans (phoebodon-tids, symmoriids, and several new cladodont chondrichthyans). In the framework of this thesis, the remains of chondrichthyans were in the main focus because their skeletons are rarely preserved in the fossil record due to the fragility of their cartilaginous skeletons. The Famennian chondrichthyans of the Maïder region often preserve three-dimensional skulls, the visceral as well as postcranial skeleton (pectoral and pelvic girdles with articulated fi ns, dorsal fi ns with fi n spines, neural arches and sometimes the caudal fi n) and even mineralized soft-tissues (muscles, liver, digestive tract). Therefore, the discovery of such remains of Devonian chondrichthyans is of importance to examine their phylogenetic relationships, their morpholog-ical disparity and to reconstruct their ecological diversity including changes in the respective ecological roles of these vertebrate groups in the marine ecosystems.

In chapter I, the palaeoenvironment of the gnathostome-bearing stratigraphic interval of the Maïder was quantitatively investigated by analysing the diversity and palaeocology of the accompanying inverte-brate faunas. For this purpose, 21 invertebrate associations from early Famennian to early Carboniferous age of the Maïder region (17 from Madene el Mrakib, four from Aguelmous) were sampled and deter-mined. Based on the composition of these associations, alpha diversity (changes in species richness at a single locality through time), ecospace occupation (three-dimensional modes of life including tiering, motility, and feeding mode) and trophic nucleus (dominant taxa of each association) were analysed. The species richness, ecospace occupation as well as the ratio between pelagic and benthic organisms were fl uctuating during the Famennian and Tournaisian. Those ecological changes correlate with numerous bio-events coinciding with fl uctuating global and/ or regional sea level and changes in oxygenation during the Devonian. Although the sea fl oor might have been a bit better oxygenated (extended ecospace includ-ing benthic modes of life) in some stratigraphic intervals, the Fammennian of the study area was mostly hypoxic to dysoxic because of the low taxonomic diversity of benthic invertebrates and the dominance of pelagic or benthic taxa tolerant to oxygen depletion. This is supported by the absence of benthic gnatho-stomes in the Maïder (including microremains).

The taphonomy of the gnathostomes of the Famennian Thylacocephalan Layer and some other Devo-nian Fossillagerstätten was investigated in Chapter II. The mineral composition of the remains of gnatho-stomes, thylacocephalans and some other invertebrates from various localities were analysed by Raman spectroscopy and X-ray diffraction. To understand the genesis of the Famennian Fossillagerstätten, the mineral analyses were combined with the current knowledge of the palaeogeography and palaecology of the Maïder region. The fossils mainly contain iron oxides (oxidised pyrite) and phosphates. The Maïder was a basin isolated by land and two submarine ridges (Tafi lalt and Maïder Platform) from neighbouring basins, which limited water exchange and thus also oxygen supply during the Devonian. This palaeogeo-graphic setting in combination with the mineral composition of the fossils, the soft-tissue preservation and the low abundance of benthos (even a complete lack of benthic chondrichthyans), the Thylacocephalan Layer with exceptionally well-preserved chondrichthyans represents the fi rst Konservat-Lagerstätte (con-servation deposit) of the Devonian of North Africa.

In chapter III, the morphology and palaeoecology of Phoebodus, a common and cosmopolitan chon-drichthyan from the Devonian (Givetian to Famennian), previously only known from isolated teeth, is

3

Abstract

described. Phoebodus saidselachus sp. nov. of the Famennian of the Maïder region is the fi rst specimen of this genus preserving body, soft-tissue and skull remains. Its body and skull are slender and more elongate than those of other Palaeozoic chondrichthyans. Phylogenetic analyses based on a data matrix including 228 characters of 65 taxa and one outgroup taxon place Phoebodus saidselachus sp. nov. within the stem elasmobranchs. Therefore, the Devonian genus Phoebodus is the oldest stem elasmobranch with an elon-gate body shape. Other stem elasmobranchs with such body shapes are known from younger strata such as the phoebodontid Thrinacodus gracia from the Carboniferous of Bear Gulch and several taxa of xenacan-thids from the Permian. Therefore, chondrichthyans were morphologically and ecologically more diverse in the Devonian before the vertebrate bottleneck of the Hangenberg Crisis than previously thought.

Chapter IV focuses on the jaw function of symmoriiform chondrichthyans. Although the fossil re-cord of Palaeozoic chondrichthyans improved in recent years, the functional morphology of anatomical elements such as the visceral skeleton are not known in detail due to the often fragmentary or deformed preservation. For example, there was a long debate about whether hyoids had a suspensory function or not (aphetohyoidean hypothesis) in symmoriids. The newly discovered chondrichthyan Ferromirum oukher-bouchi gen. et sp. nov. from the Maïder Basin has exceptionally well-preserved and undeformed mandib-ular and branchial arches. The remains of the specimen were three-dimensionally reconstructed on the basis of CT-scans using the 3D reconstruction software Mimics. 3D-prints of the virtually reconstructed specimen allowed to mechanically examine the function of the mandibular and branchial arches. Due to the arrangement of the hyoids and jaws, it can be confi rmed that the hyoids had a suspensory function (aphetohyoidean hypothesis falsifi ed). Moreover, because of the confi guration of the jaw-articulation, the lower jaws performed a lateral and outward rotation when the chondrichthyan opened its mouth. As a result of this movement, the predatory success was probably improved since a greater portion of the dentition becomes functional than previously thought. This kind of jaw function is not known from recent chon-drichthyans and possibly vanished with the extinction of the symmoriids.

As general conclusion, the Famennian Konservat-Lagerstätten of the Maïder Basin bear abundant remains of various early gnathostomes and thylacocephalans. These gnathostomes were fossilized under oxygen depleted conditions on the sea fl oor of the Maïder Basin as corroborated by 1) the preservation in ferruginous nodules, 2) by the low diversity of accompanying benthic invertebrate, 3) by the domi-nance of taxa living in the water column (both invertebrates and vertebrates) and 4) the co-occurrence of benthic taxa tolerant to anoxic to dysoxic conditions. The two newly described taxa of chondrichthyans (Phoebodus saidselachus sp. nov and Ferromirum oukherbouchi gen. et sp. nov.) yielded new data on the morphology, phylogeny, diversity and functional morphology of Devonian chondrichthyans. Considering that much more taxa of early gnathostomes were discovered than presented here, the Famennian Konser-vat-Lagerstätten of the Maïder are of great importance to further study disparity and diversity trends of these early vertebrates as well as their ecology and evolution in the future.

INTRODUCTION

7

Introduction

Devonian Period: an overview

The Devonian (~419 to 259 Ma years) is the third

period of the Palaeozoic. It is subdivided into four

epochs and seven stages: the Early (Lochkovian,

Pragian, Emsian), Middle (Eifelian, Givetian) and

Late (Frasnian, Famennian) Devonian (Cohen et

al. 2013, updated 2018). At this time, two main

continents persisted: the larger continent Gond-

wana south of the equator and Euamerica (also

known as Laurussia), which was situated north-

east of Gondwana (Scotese 2001; Fig. 1A). The

two continents were separated from each other by

the Palaeotethys and the Variscan Sea (Neugebau-

er 1988). The climate throughout the Devonian

was generally warm to tropical (30°C) interrupted

by a somewhat cooler period (23 to 25°C) during

the Middle Devonian (Joachimski et al. 2009; Fig.

1B). Towards the end of the Devonian, the climate

cooled down for a second time (Joachimski &

Buggisch 2002).

Among others, the Devonian period is famous

for the rise of land plants, in particular the evolu-

tion of vascular plants, and the establishment of

the fi rst forest ecosystems (Rettalack 1997; Algeo

and Scheckler 1998; Stein et al. 2012). In the ma-

rine realm, the fi rst ammonoids with coiled shells

evolved from the straight-shelled to slightly coiled

bactritoids during the Early Devonian (Korn &

Klug 2002). In the context of my thesis, howev-

er, it is the great evolutionary success of jawed

fi shes in that time. Accordingly, the Devonian

is also called the “Age of Fish” because various

groups of jawed fi sh (gnathostomes) radiated and

established in the early marine and freshwater en-

vironments (Fig. 2A). Several of the main groups

of gnathostomes survived until today such as sar-

copterygians (lobe-fi nned fi sh), actinopterygians

(ray-fi nned fi sh), and chondrichthyans (cartilagi-

nous fi sh). By contrast, two important Devonian

groups of gnathostomes such as the placoderms

and ‘acanthodians’ (a probably paraphyletic

group of cartilaginous fi sh) vanished throughout

Earth`s history (Fig. 2B). The placoderms had a

characteristic bony armor consisting of thick der-

mal plates in the head and thorax region while

their tail was naked or covered by scales and they

were roaming the waters for around ~120 Ma

years (Silurian to Devonian; Long & Trinajstic

2010). ‘Acanthodians’ persisted longer (Silurian

to Permian) than the placoderms and they include

small chondrichthyans exhibiting usually several

pairs of fi ns that usually carry spines, hence the

name (Hanke et al. 2001; Karatajute-Talimaa &

Smith 2002; Burrow 2003, Denison 1979). Their

phylogenetic relationships within the group and

to other fi sh groups are still not clarifi ed due to

their fossil record of often complete but heavily

fl attened fossils (Blais 2017). Most phylogenetic

studies revealed them as a paraphyletic group of

stem chondrichthyans (Brazeau 2009; Davis et al.

2012; Zhu et al. 2013; Giles et al. 2015; Long et

al. 2015; Burrow et al. 2016; Coates et al. 2017)

but some taxa might also represent stem osteich-

thyans (Brazeau 2009, Davis et al. 2012).

A fundamental step in evolution, namely the

transition from fi sh to tetrapod (four-limbed ver-

tebrates) and thus from aquatic to terrestrial life

took place during the Devonian. Fossil bodies

of tetrapods and closely related tetrapodomorph

fi shes are known from the Middle and Late De-

vonian (e.g., Campbell & Bell 1977; Ahlberg

1998; Ahlberg & Clack 2006; Ahlberg et al. 1994,

2005, 2008; Lebedev & Clack 1993; Lebedev &

Coates 1995; Zhu et al. 2002; Shubin et al. 2004;

Daeschler et al. 2006). Tetrapodomorph fi shes

such as the elpistostegalians are sarcopterygians

already exhibiting tetrapod-like characters in their

fi ns (e.g., Panderichthys in Boisvert et al. 2008;

Clack 2012). This fact in combination with the

mostly aquatic lifestyle of Devonian tetrapods in-

cluding the famous Acanthostega and Ichthyoste-

ga evidence the initial evolution of limbs from

fi ns in aquatic environments (Coates 1996; Coates

& Clack 1995; Coates & Ruta 2007; Clack 2012).

8

Introduction

As mentioned above, the Devonian was a pe-

riod of early animal and plant radiation and of

evolutionary key events such as the fi sh-tetrapod

transition. However, the Devonian ecosystem

also faced several extinction events (Walliser

1996; House 2002; Fig. 3). The most fundamental

changes in this early ecosystem occurred at the

latest Frasnian (Kellwasser Crisis; e.g., McGhee

1988; Buggisch 1991; McGhee 2001; Sandberg

et al. 2002; Gereke & Schindler 2012) and at the

end-Famennian (Hangenberg Crisis; e.g., Caplan

& Bustin 1999; Kaiser et al. 2006, 2008, 2015;

Carmichael et al. 2015; Becker et al. 2016). The

Kellwasser event strongly affected the marine

Figure 1. Palaeogeography and temperature curve of the Devonian. A. Palaeomap shows continents and

oceans of the Late Devonian (370 Ma years), modifi ed map from Deep Time Maps (Blakey 2016, https: //

deeptimemaps.com). B. Temperature curve of the surface waters, adopted from Joachimski et al. (2009).

9

Introduction

biodiversity, which is evident by the loss of about

72-80 % of all species (McGhee 2014). The Han-

genberg Crisis is also regarded as a bottleneck

in vertebrate evolution as many habitats of ear-

ly vertebrates underwent fundamental changes:

while sarcopterygians suffered a severe loss in di-

versity and the placoderms got extinct, chondrich-

thyans and actinopterygians diversifi ed rapidly af-

ter the crisis (Sallan & Coates 2010). Causes for

the changes in the environment and biodiversity

during the Late Devonian are still under debate.

Some possible causes are marine anoxia (Caplan

Figure 2. Devonian groups of gnathostomes. A. Biodiversity through time, source: Benton (2005). B.

Reconstructions of some early gnathostomes: 1. Bothriolepis, 2. Remigolepis, 3. Groenlandaspis, 4. Ho-

loptychius, 5. Moythomasia, 6. Culmacanthus, 7. Akmonistion. Reconstructions are taken from Sampson

(1956); Jessen (1968); Lauder & Liem (1983); Young (1989a, b, 2007); Long (1983, 1991); Cloutier &

Schultze (1996); Coates & Sequeira (2001); Choo (2015).

10

Introduction

& Bustin 1999; Riquier et al. 2006), sea level fl uc-

tuations (Kaiser et al. 2006), global cooling (Joa-

chimski & Buggisch 2002), eutrophication (Al-

geo & Scheckler 1998; Algeo et al. 1995, 2001)

and decreased marine selenium level (Long et al.

2015).

Devonian of Morocco

Morocco can be regarded as a window into

Earth`s deep history because its outcrops yield

many geological, sedimentological and palaeon-

tological information about past ecosystems from

the Proterozoic to today. During the Devonian

period, Morocco was situated at the northwestern

margin of Gondwana and a lot of its surface was

covered by an epicontinental sea (Scotese 2002;

Dopieralska 2009). Exposed Devonian sediments

cover a large area of about 20000 km2, which

often bear highly fossiliferous strata (Kaufmann

1998). Some of the most famous regions for De-

vonian fossils are the Tafi lalt and the Maïder in

the eastern Anti-Atlas. In these regions, two ma-

rine basins (Tafi lalt and Maïder Basin) formed in

the Palaeozoic, which were connected via the Ta-

fi lalt platform with shallower water (Wendt 1985,

1995; Wendt et al. 2006; Fröhlich 2004; Lubeseder

et al. 2010; Fig. 4). From this region, many fossil

groups of marine animals have been documented.

Particularly invertebrates are extremely abundant

such as trilobites (e.g., Struve 1990; Klug et al.

2009; Chatterton and Gibb 2010), crinoids (e.g.,

Klug et al. 2003; Webster et al. 2005; Berkows-

ki & Klug 2012), brachiopods (e.g., Franchi et al.

2012; Halamski & Baliński 2013; Tessitore et al.

2013; Sartenaer 1998, 1999, 2000), bivalves (e.g.,

Kříž 2000; Hryniewicz et al. 2017), and cepha-

lopods including ammonoids (e.g., Korn 1999;

Klug 2002; Klug et al. 2008; Klug et al. 2016;

Becker 2002; Kröger 2008; De Baets et al. 2010,

2012; Korn & Bockwinkel 2017; Korn et al. 2014,

2015a, b, 2016a,b). Due to the high abundance

and/ or exceptional preservation of macrofos-

sils, several localities could be actually regarded

as Fossillagerstätte (Frey et al. submitted, Chap-

ter II). As far as vertebrates are concerned, their

peak abundance is in the Late Devonian strata of

the eastern Anti-Atlas. Previously, the record of

articulated remains of Devonian vertebrates was

limited to more or less complete body and skull

parts of placoderms and sarcopterygians (Leh-

Figure 3. The big fi ve mass-extinctions after Sepkoski (2002) are marked by red lines. During the Devoni-

an, two major crises (Kellwasser and Hangenberg) shaped the early vertebrate biodiversity. Figure adopted

from Friedman & Sallan (2012).

11

Introduction

mann 1956, 1964, 1976, 1977, 1978; Lelièvre &

Janvier 1986, 1988; Lelièvre et al. 1993; Rücklin

2010, 2011; Rücklin et al. 2015; Rücklin & Clé-

ment 2017; Fig. 5 A-D, J). By contrast, actinopte-

rygians and chondrichthyans are rare and only fi n

spines, teeth, scales and few remains of isolated

jaws were published (Termier 1936; Lehman

1976; Derycke 1992; Hampe et al. 2004; Dery-

cke et al. 2008, 2014; Ginter et al. 2002; Klug

et al. 2016; Derycke 2017; Fig. 5E-I). Recently,

new material of Famennian (Late Devonian) plac-

oderms, sarcopterygians, actinopterygians and

chondrichthyans were found in the Maïder Basin

(Frey et al. 2018, Chapter I, Fig. 6 A-D). In par-

ticular, the chondrichthyans are well-preserved

with sometimes three-dimensional skulls as well

as more or less complete and articulated bodies.

In this PhD project, I focused on these early chon-

drichthyans because they bear a plethora of new

anatomical, ecological and phylogenetic informa-

tion about this group (Chapter III and IV).

Global mass extinction events such as the Kell-

wasser Crisis (latest Frasnian; Wendt and Belka

1991) and the Hangenberg Crisis (end-Devoni-

an; e.g. Korn et al. 2004; Kaiser et al. 2011) are

recognizable along with some smaller bio-events

in the Late Devonian of Morocco (House 1985;

Becker 1993; Hartenfels & Becker 2009, 2016a,

b). These events often coincided with dysaerobic

or anoxic conditions and/ or transgressions on a

regional scale (Wendt and Belka 1991; Kaiser et

al. 2015; Hartenfels 2011). The new material of

gnathostomes from the Maïder comes from this

environmentally unstable interval between the

Kellwasser and Hangenberg crises. For this rea-

son, I also investigated changes in environmental

conditions, which affected the early gnathostomes

faced in this marine basin in detail (Frey et al.

2018; Chapter I).

Palaeozoic chondrichthyans

Devonian chondrichthyans are characterized by

a skeleton consisting of calcifi ed tessellated car-

tilage, multiple rows of teeth that are replaced

throughout life and by a body often covered by

placoid scales. Extant chondrichthyans include

the subclasses Elasmobranchii (sharks and rays;

around 1100 species) and Holocephali (chimaeras;

Figure 4. Topography and bathymetry of the Maïder and Tafi lalt area in the southeastern Anti-Atlas

during the Late Devonian. Figure is adopted from Dopieralska (2009).

12

Introduction

around 50 species; Compagno et al. 2005). Some

of the oldest known putative remains of chon-

drichthyans are scales from the Llandovery (Silu-

rian) of Central Asia: e.g., Mongolepis, Teslepis,

Sodolepis, Udalepis, Xinjiangichthys, Shiqianole-

pis, Elegestolepis and Tuvalepis (Karatajūtė-Tali-

maa 1973, 1995; Karatajūtė-Talimaa et al. 1990;

Karatajūtė-Talimaa & Novitskaya 1992; Novits-

kaya & Karatajūtė-Talimaa 1986; Zhu 1998; San-

som et al. 2000; Žigaitė & Karatajūtė-Talimaa

2008). Probably even older chondrichthyan scales

from the Ordovician were reported such as Tan-

talepis and Areyongalepis (Sansom et al. 1996,

2012; Young 1997, 2000; Fig. 7A).

The oldest remains that are more widely ac-

cepted as remains of chondrichthyans are the teeth

of Leonodus from the Early Devonian (Mader

1986, Fig. 7B). First skeletons of stem chondrich-

thyans were documented from the Early/Middle

Devonian; these fi nds comprise braincases with

parts of the visceral skeleton of Doliodus (Miller

et al. 2003; Maisey et al. 2009, 2017; Fig. 8A, B),

Pucapampella (Janvier & Suárez-Riglos, 1986,

Maisey & Anderson 2001), Gladbachus (Heidtke

& Krätschmer 2001; Coates et al. 2018; Fig. 8C,

D) and Anarctilamna (Young 1982).

From the Famennian (Late Devonian) on-

wards, remains of chondrichthyans become more

abundant although many discoveries mainly in-

clude isolated fi n spines (e.g., ctenacanthids;

Figure 5. Remains of Late Devonian gnathostomes from Morocco. A-D. Skull plates of the placoderm

Driscollaspis pankowskiorum Rücklin et al., 2015, dorsal (A-B) and lateral (C-D) views, scale bar = 5

cm. E-F. Teeth of Phoebodus gothicus Ginter, 1990, scale bar = 0.5 mm. G. Symphyseal tooth-whorl of

an acanthodian, scale bar = 0.5 mm. H-I. Teeth of actinopterygians, scale bar = 100 μm. J. Teeth and jaw

remains of onychodontid sarcopterygian. Sources of fi gures: A-D.: Rücklin et al. (2015); E-G.: Ginter et

al. (2002); H-I.: Derycke et al. (2008); J: Lehmann (1976).

13

Introduction

Maisey 1981, 1982a, 1984a) and teeth of, e.g.,

Omalodontiformes Turner, 1997, Protacrodon-

toidea Zangerl, 1981 and Orodontiformes Zangerl,

1981 (Ginter et al. 2010). One of the most famous

and best documented Famennian chondrichthyan

known from complete and articulated skeletons is

Cladoselache Dean, 1894A from the Cleveland

Shales of Ohio, USA. Cladoselache has a shark-

like morphology including a torpedo-shaped

body with a crescent outlined caudal fi n, paired

pectoral and pelvic fi ns, two dorsal fi ns with fi n

spines and teeth arranged in several tooth fi les

(e.g. Dean 1894A, 1909; Bendix-Almgreen 1975;

Harris 1938a, b; Maisey 1989b, 2007; Schaeffer

1981; Williams 2001; Woodward & White 1938).

These early chondrichthyans were assigned to

elasmobranchs for a long time but recent stud-

ies provided evidence that Cladoselache is more

closely related to holocephalans (Coates et al.

2017; Fig. 9A, 9E). Coates et al. (2017) assigned

another common and divers Palaeozoic group of

chondrichthyans, namely the Symmoriiformes

Figure 6. Late Devonian localities in the Maïder region bearing remains of gnathostomes. A. Madene el

Mrakib, B. Bid er Ras, C. Shivering layer contains nodules with thylacocephalan arthropods and gnatho-

stomes, D. Fin remains of a chondrichthyan in the fi eld.

14

Introduction

Zangerl, 1981, to the holocephalans. Symmoriid

chondrichthyans persisted from the Devonian to

the Permian and exhibit symplesiomorphies such

as a whip-like structure connected to the metapte-

rygium of both pectoral fi ns, a reduced fi rst dorsal

fi n and reduced or specialized dorsal fi n spines

(e.g. Zangerl 1981; Lund 1985, 1986; Coates &

Sequeira 2001). In Cobelodus Cope, 1893, Sym-

morium and Denaea Zangerl, 1981, the anterior

of the two dorsal fi ns and the dorsal fi n spines are

absent while Falcatus, Damocles, Stethacanthus

and Akmonistion exhibit a derived structure at the

position of the anterodorsal fi n (Zangerl 1981,

1984, 1990; Zangerl & Case 1986; Williams 1985;

Fig. 9F-H). A so-called spine-brush complex is

present in Stethacanthus and Akmonistion, which

consists of an anterior spine and posteriorly of a

brush out of globular calcifi ed cartilage covered

by large spiny scales (Coates et al. 1998; Coates

& Sequeira 2001). Instead of this spine-brush

complex, Falcatus and Damocles dorsally have a

hook-like appendage (Lund 1985, 1986). Because

such structures are absent in modern chondrich-

thyans, their function is not yet known. The spine-

brush complex may speculatively have served

to scare off predators due to the resemblance of

this complex to a large, opened mouth (Zangerl,

1984). This interpretation appears doubtful be-

cause the spine-brush complex and the hooks are

only found in male specimens and it appears more

plausible that they played a role in mating (Lund

1985; Coates et al. 1998). The affi nity of sym-

moriids to holocephalans is further supported by

anatomical details seen in a three-dimensionally

preserved braincase of Dwykaselachus oosthui-

zeni Oelofsen 1986 by Coates et al. (2017): this

specimen shows chimaeroid-like character states

such as, for example, an elevated midbrain cham-

ber, large orbits and a similarly arranged otic lab-

yrinth (Coates et al. 2017). In the Famennian of

Morocco, we discovered well-preserved remains

of two new taxa of symmoriids that give new in-

sights into the ecology of the entire group (Frey et

al. in prep., Chapter IV) .

Another group of holocephalans that get some

attention are the Eugeneodontiformes that were

abundant during the Permian and Triassic (Zan-

gerl 1981). Their tooth whorls are planispirally ar-

ranged forming sometimes a saw-blade like denti-

tion such as in Edestus and Helicoprion (Ginter et

al. 2010; Fig. 10). Both taxa might have used the

tooth whorls for slashing medium-sized to large

prey (Itano 2014, 2015, 2018). Generally, holo-

cephalans were taxonomically and ecologically

more divers during the Palaeozoic than today and

many different groups have been documented

Figure 7. Putative scales and teeth of earliest

chondrichthyans. A. Scales of Tantalepis gate-

housei Sansom et al., 2012 from the Ordovician,

scale bar = 50 μm. B. Teeth of Leonodus carlsi

Mader, 1986 from the early Devonian, scale bar =

0.5 mm. Source of picture: Sansom et al. (2012)

and Ginter et al. (2010).

15

Introduction

from the Carboniferous of the Bear Gulch Lime-

stone in Montana, USA (Lund & Grogan 1997;

Lund et al. 2012, 2015).

Compared to holocephalans, fewer groups of

Palaeozoic elasmobranchs were discovered so far.

Among those, representatives of the phoebodon-

tids, xenacanthids, hybodontids and ctenacanthids

are locally quite common and thus the best docu-

mented. Previously, phoebodontids, a nearly cos-

mopolitan group, were known by a great number

of isolated teeth and by articulated skeletons of a

single species, namely Thrinacodus gracia (Gro-

gan and Lund, 2007) (Ginter et al. 2010; Fig. 11).

Figure 8. Stem chondrichthyans of Early and Middle Devonian age. A-B. Fossil remains and illustration

of Doliodus problematicus Miller et al., 2003, scale bar = 1 cm. C-D. Threedimensional reconstruction

of Gladbachus adentatus Heidtke and Krätschmer, 2001 based on computer tomographs, scale bar = 5

cm. Abbreviations: bhy, basihyal; bbra; anterior basibranchial; bbrp, posterior basibranchial; cbr, cerato-

branchials (I-V?); chy, ceratohyal; hb, hypobranchial; mc, Meckel’s cartilage; mmd, location of mucous

membrane denticles on counterpart; na, neural arches; nc, neurocranium; or, orbital ring; pop, postorbital

process; pq, palatoquadrate; pfs, pectoral fi n-spines; rad, radials; sco, scapulocoracoid; sp, partial spines;

sym, symphysis; tth, area with in situ teeth; thf, in situ tooth family. Figures adopted from Miller et al.

(2003) and Coates et al. (2018).

16

Introduction

However, the very common genus Phoebodus was

solely known by their widespread characteristic

tricuspid teeth and isolated putative fi n spines in

spite of its rather cosmopolitan distribution during

the Middle and Late Devonian (Ginter et al. 2002;

2010). Recently, we found the fi rst remains of ar-

ticulated skulls and postcrania of Phoebodus in

the Famennian of the Maïder region in Morocco

(Frey et al. in prep., Chapter III).

Xenacanthids are rather closely related to

phoebodontids and their remains have been doc-

umented from Late Devonian to Triassic occur-

rences (Ginter et al. 2010, Frey et al. in prep.,

Figure 9. Phylogeny and some representatives of early chondrichthyans. A. phylogenetic relationships

of early and some extant chondrichthyans adopted from Coates et al. (2018), red: stem chondrichthyans,

blue: elasmobranchs, yellow; holocephalans. B. Onychoselache traquairi (Dick, 1978), C. Squalus sp.,

D. Triodus sessilis, E. Cladoselache Dean, 1894A, F. Akmonistion zangerli Coates and Sequeira, 2001,

G. Cobeldodus Cope, 1893 H. Falcatus falcatus Lund, 1985. Reconstructions: B. Coates & Gess (2007);

C-D. Schaeffer & Williams (1977); E. Schaeffer (1967); F. Coates & Sequeira (2001); G. Zangerl and Case

(1976); H. Lund (1985).

17

Introduction

Chapter III). They had an elongated body with a

dorsal fi n extending along the entire body length,

a dorsal cranial spine and diplodont teeth (crown

with two long lateral cusps and a reduced medi-

an cusp; Dick 1981; Heidtke 1982, 1999; Hot-

ton 1952; Schaeffer 1981; Solér-Gijon & Hampe

1998; Hampe 2003; Heidtke et al. 2004; Fig. 9D).

A group of early chondrichthyans that is phy-

logenetically most closely related to the Neosela-

chii (modern sharks and rays) are the hybodonts

(Maisey 1984b; Maisey et al. 2004; Coates &

Gess 2007; Fig. 9A). The hybodonts are a group

that persisted from the Devonian to the Creta-

ceous (Mesozoic). They show derived conditions

in many parts of their skeleton compared to oth-

er early elasmobranchs. In addition to many dif-

ferences in the braincase, their shoulder girdle is

similar to that of extant elasmobranchs (Fig. 9B);

the pectoral fi ns have a tribasal arrangement (bas-

al elements are separated into propterygium, me-

sopterygium and metapterygium); a puboischiad-

Figure 10. Helicoprion bessonowi Karpinsky, 1899A, tooth spiral, scale bar = 5 cm. Source of picture:

Ginter et al. (2010).

Figure 11. The phoebodontid Thrinacodus gracia (Grogan & Lund, 2008) from the Carboniferous of Bear

Gulch, Montana. Scale bar = 5 cm. Picture taken from Grogan & Lund (2008).

18

Introduction

ic bar (left and right halves of the pelvic girdle

are fused) is present; the palatoquadrate is not the

cleaver-shaped (instead they have a lateral quad-

rate fl ange); and labial cartilages are present (e.g.

Dick 1978; Dick & Maisey 1980; Maisey 1982b,

1983, 1987, 1989; Maisey and de Carvalho 1997;

Coates & Gess 2007; Lane 2010; Lane & Maisey

2009, 2012; Coates & Tietjen 2018).

In this thesis, I focus on two groups of chon-

drichthyans, namely the phoebodontids and sym-

moriids. The recently discovered material of these

two groups of the Devonian of Morocco yields

important information about the phylogenetic

relationships and ecomorphological disparity of

some of the earliest chondrichthyans.

References

Ahlberg, P. 1998. Postcranial stem tetrapod remains from the Devonian of Scat Craig, Morayshire, Scotland. Zoological Journal of the Linnean Soci-ety, 122, 99-141.

Ahlberg, P. E., and Clack, J. A. 2006. Palaeontology: a fi rm step from water to land. Nature, 440(7085), 747.

Ahlberg, P. E., Clack, J. A., and Blom, H. 2005. The axial skeleton of the Devonian tetrapod Ichthyoste-ga. Nature, 437, 137-140.

Ahlberg, P. E., Clack, J. A., Luksevics, E., Blom, H., and Zupins, I. 2008. Ventastega curonica and the origin of tetrapod morphology. Nature, 453, 1199-1204.

Ahlberg, P. E., Luksevics, E., and Lebedev, O. 1994. The fi rst tetrapod fi nds from the Devonian (Upper Fammenian) of Latvia. Philosophical Transactions of the Royal Society of London, B343, 303-328.

Algeo, T. J., Berner, R. A., Maynard, J. B., Scheckler, S. E., 1995. Late Devonian oceanic anoxic events and biotic crises: ‘rooted’ in the evolution of vascu-lar plants. GSA Today, 5, 63-66.

Algeo, T. J., Scheckler, S. E., 1998. Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events. Philosophical Transactions of the Royal Society of London B, 353, 113-130.

Algeo, T. J., Scheckler, S. E., Maynard, J. B., 2001. Ef-fects of Middle to Late Devonian spread of vascular

land plants and weathering regimes. In Gensel, P. G., Edwards, D. (Eds.), Plants invade the land. Co-lumbia University Press, New York, pp. 213-237.

Becker, R. T., 1993. Anoxia, eustatic changes, and Up-per Devonian to lowermost Carboniferous global ammonoid diversity, in: House, M. R. (Ed.), The Ammonoidea: environment, ecology, and evolu-tionary change. Systematic Association Special Volume 47, 115-164.

Becker, R. T., House, M. R., Bockwinkel, J., Ebbighau-sen, V., and Aboussalam, Z. S., 2002. Famennian ammonoid zones of the eastern Anti-Atlas (south-ern Morocco). Münstersche Forschungen zur Geo-logie und Paläontologie, 93, 159-205.

Becker, R. T., Kaiser, S. I., Aretz, M., 2016. Review of chrono-, litho- and biostratigraphy across the glob-al Hangenberg Crisis and Devonian-Carboniferous Boundary. Geological Society, London, Special Publications 423(1), 355386.

Bendix-Almgreen, S. E., 1975. The paired fi ns and shoulder girdle in Cladoselache, their morphology and phyletic signifi cance. Colloques internatio-naux Centre national de la recherche scientifi que (France), 111-123.

Benton, M. J., 2005. Vertebrate Palaeontology, Black-well, 3rd edition.

Berkowski, B., and Klug, C., 2012. Lucky rugose cor-als on crinoid stems: unusual examples of subep-idermal epizoans from the Devonian of Morocco. Lethaia, 45(1), 24-33.

Blais, S. A., 2017. Precise occlusion and trophic niche differentiation indicate specialized feeding in Early Devonian jawed vertebrates. Facets, 2(1), 513530.

Boisvert, C. A., Mark-Kurik, E., and Ahlberg, P. E., 2008. The pectoral fi n of Panderichthys and the or-igin of digits. Nature, 456, 636-638.

Brazeau, M.D., 2009. The braincase and jaws of a De-vonian ‘acanthodian’ and modern gnathostome ori-gins. Nature, 457, 305308.

Buggisch, W., 1991. The global Frasnian-Famenni-an “Kellwasser Event”. Geologische Rundschau, 80(1), 4972.

Burrow, C.J., 2003. Redescription of the gnathostome fi sh fauna from the mid-Palaeozoic Silverband For-mation, the Grampians, Victoria. Alcheringa: An Australasian Journal of Palaeontology, 27, 37-49. doi:10.1080/03115510308619543.

Burrow, C.J., den Blaauwen, J., Newman, M., and Davidson, R., 2016. The diplacanthid fi shes (Ac-anthodii, Diplacanthiformes, Diplacanthidae) from the Middle Devonian of Scotland. Palaeontologia Electronica 19.1.10A, 1-83, palaeo-electronica.org/content/2016/1398-scottish-diplacanthid-fi shes.

19

Introduction

Campbell, K. S. W., and Bell, M. W., 1977. A primitive amphibian from the Late Devonian of New South Wales. Alcheringa, 1, 369-381.

Caplan, M. L., Bustin, R. M., 1999. Devonian-Carbon-iferous Hangenberg Mass extinction event, wide-spread organic-rich mudrock and anoxia: causes and consequences. Palaeogeography, Palaeocli-matology, Palaeoecology, 148, 187207.

Carmichael, S. K., Waters, J. A., Batchelor, C. J., Cole-man, D. M., Suttner, T. J., Kido, E., McCain Moore, L., Chadimová, L., 2015. Climate instability and tipping points in the Late Devonian: Detection of the Hangenberg Event in an open oceanic island arc in the Central Asian Orogenic Belt. Gondwana Re-search, 32, 213231.

Chatterton, B. D., and Gibb, S. 2010. Latest Early to early Middle Devonian trilobites from the Erben-ochile bed, Jbel Issoumour, southeastern Morocco. Journal of Paleontology, 84(6), 1188-1205.

Choo, B., 2015. A New Species of the Devonian Ac-tinopterygian Moythomasia from Bergisch Glad-bach, Germany, and Fresh Observations on M. durgaringa from the Gogo Formation of Western Australia. Journal of Vertebrate Paleontology, 35(4). http://www.bioone.org/doi/full/10.1080/02724634.2015.952817

Clack, J. A., 2012. Gaining Ground: The Origin and Evolution of Tetrapods. 2nd edition, Indiana Uni-versity Press, Bloomfi eld, IN, 523 p.

Cloutier, R., and Schultze, H.P., 1996. Porolepiform fi shes (Sarcopterygii). In: Schultze H-P. and Clout-ier R. (eds.) Devonian Fishes and Plants of Migua-sha, Quebec, Canada, pp. 248 – 270, Verlag Dr. Friedrich Pfeil, München.

Coates, M. I., 1996. The Devonian tetrapod Acantho-stega gunnari Jarvik: Postcranial anatomy, basal tetrapod relationships and patterns of skeletal evo-lution. Transactions of the Royal Society of Edin-burgh: Earth Sciences, 87, 363-421.

Coates, M. I., and Clack, J. A., 1995. Romer’s gap: Tet-rapod origins and terrestriality. Bulletin du Museum National d’Histoire Naturelle, 4(17), 373-388.

Coates, M. I., Finarelli, J. A., Sansom, I. J., Andreev, P. S., Criswell, K. E., Tietjen, K., and La Riviere, P. J., 2018. An early chondrichthyan and the evolution-ary assembly of a shark body plan. Proceedings of the Royal Society B, 285(1870), 20172418.

Coates, M. I., and Gess, R. W., 2007. A new recon-struction of Onychoselache traquairi, comments on early chondrichthyan pectoral girdles and hy-bodontiform phylogeny. Palaeontology, 50(6), 1421-1446.

Coates, M. I., Gess, R. W., Finarelli, J. A., Criswell, K. E., & Tietjen, K., 2017. A symmoriiform chon-

drichthyan braincase and the origin of chimaeroid fi shes. Nature, 541(7636), 208.

Coates, M. I., and Ruta, M., 2007. Skeletal changes in the transition from fi ns to limbs. In Hall, B. K. (ed.). Fins into Limbs: Evolution, Development, and Transformation. University of Chicago Press, Chicago, pp. 15-37.

Coates, M. I., Sansom, I. J., and Smith, M. M., 1998. Spines and tissues of ancient sharks. Nature, 396, 729-730.

Coates, M. I., and Sequeira, S. E. K., 2001. A new stethacanthid chondrichthyan from the Lower Car-boniferous of Bearsden, Scotland. Journal of Verte-brate Paleontology, 21, 754-766.

Coates, M. I., and Tietjen, K., 2018. The neurocranium of the Lower Carboniferous shark Tristychius ar-cuatus (Agassiz, 1837). Earth and Environmental Science Transactions of the Royal Society of Edin-burgh, 108(1), 19-35.

Cohen, K.M., Finney, S.C., Gibbard, P.L. and Fan, J.X., 2013 (updated 2018). The ICS International Chronostratigraphic Chart. Episodes, 36, 199-204.

Compagno, L., Dando, M., and Fowler, S., 2005. Sharks of the World. 368 pp. Princeton University Press (Princeton and Oxford).

Cope, E. D., 1893. On Symmorium and the position of the cladodont sharks. American Naturalist, 27, 999-1001.

Daeschler, E. B., Shubin, N. H., and Jenkins, F. A., Jr., 2006. A Devonian tetrapod-like fi sh and the evolu-tion of the tetrapod body plan. Nature, 440, 757-763.

Davis, S.P., Finarelli, J.A., and Coates, M.I., 2012. Ac-anthodes and shark-like conditions in the last com-mon ancestor of modern gnathostomes. Nature, 486, 247- 250.

Dean, B. 1894A. A new cladodont from the Ohio Wa-verly, Cladoselache newberryi n. sp. Transactions of the New York Academy of Sciences, 13, 115-119.

Dean, B., 1894. Contributions to the morphology of Cladoselache (Cladodus). Journal of Morphology, 9(1), 87-114.

Dean, B., 1909. Studies on fossil fi shes (sharks, chi-maeroids and arthrodires. Memoirs of the American Museum of Natural History, 9(5), 1-287.

De Baets, K., Klug, C., and Monnet, C. 2013. Intra-specifi c variability through ontogeny in early am-monoids. Paleobiology, 39(1), 75-94.

De Baets, K., Klug, C., and Plusquellec, Y. 2010. Zlíchovian faunas with early ammonoids from Mo-rocco and their use for the correlation of the eastern Anti-Atlas and the western Dra Valley. Bulletin of

20

Introduction

Geosciences, 85(2), 317-352.

Denison, R.H., 1979. Handbook of paleoichthyol-ogy, Part 5: Acanthodii. Gustav Fischer Verlag, Stuttgart, Germany. 222 p.

Derycke, C., 1992. Microrestes de Sélaciens et autres Vertébrés du Dévonien supérieur du Maroc. Bulle-tin du Muséum national d’Histoire Naturelle, Sec-tion C, Sciences de la terre, paléontologie, géolo-gie, minéralogie 14 (1), 15-61.

Derycke, C., 2017. Paléobiodiversité des gnathos-tomes (chondrichthyens, acanthodiens et actinopté-rygiens) du Dévonien du Maroc (NW Gondwana), in: Zouhri, S. (ed), Paléontologie des vertébrés du Maroc: état des connaissance, Mémoires de la So-ciété Géologique de France 180, p. 624.

Derycke, C., Olive, S., Groessens, E., Goujet, D., 2014. Paleogeographical and paleoecological con-straints on Paleozoic vertebrates (chondrichthyans and placoderms) in the Ardenne Massif Shark ra-diations in the Famennian on both sides of the Pa-laeotethys. Palaeogeography, Palaeoclimatology, Palaeoecology 414, 61-67.

Derycke, C., Spalletta, C., Perri, M. C., Corradini, C., 2008. Famennian chondrichthyan microremains from Morocco and Sardinia. Journal of Paleontol-ogy 82(5), 984995.

Dick, J. R. R., 1978. On the Carboniferous shark Tristy-chius arcuatus Agassiz from Scotland. Transaction of the Royal Society of Edinburgh, 70, 63-109.

Dick, J. R. R., 1981. Diplodoselache woodi gen. et sp. nov., an early Carboniferous shark from the Mid-land Valley of Scotland. Transaction of the Royal Society of Edinburgh, 72, 99-113.

Dick, J. R. F., and Maisey, J. G., 1980. The Scottish Lower Carboniferous shark Onychoselache traqu-airi. Palaeontology 23, 363-374.

Dopieralska, J. 2009. Reconstructing seawater circula-tion on the Moroccan shelf of Gondwana during the Late Devonian: Evidence from Nd isotope composi-tion of conodonts. Geochemistry, Geophysics, Geo-systems, 10, Q03015,doi:10.1029/2008GC002247.

Franchi, F., Schemm-Gregory, M., and Klug, C., 2012. A new species of Ivdelinia Andronov, 1961 and its palaeoecological and palaeobiogeographical impli-cations (Morocco, Givetian). Bulletin of Geosci-ences, 87(1), 1-11.

Frey, L., Rücklin, M., Korn, D., and Klug, C. 2018. Late Devonian and Early Carboniferous alpha di-versity, ecospace occupation, vertebrate assem-blages and bio-events of southeastern Morocco. Palaeogeography, Palaeoclimatology, Palaeoecol-ogy, 496, 1-17.

Friedman, M., and Sallan, L. C., 2012. Five hundred

million years of extinction and recovery: a Pha-nerozoic survey of large-scale diversity patterns in fi shes. Palaeontology, 55(4), 707-742.

Fröhlich, S. 2004. Evolution of a Devonian carbonate shelf at the northern margin of Gondwana (Jebel Rheris,eastern Anti-Atlas, Morocco). Unpublished PhD Thesis, University of Tübingen, Germany.

Gereke, M., Schindler, E., 2012. “Time-specifi c facies” and biological crisis - the Kellwasser event inter-val near the Frasnian/Famennian boundary (Late Devonian). Palaeogeography, Palaeoclimatology, Palaeoecology, 367, 19-29.

Giles, S., Friedman, M., and Brazeau, M. D., 2015. Os-teichthyan-like cranial conditions in an Early De-vonian stem gnathostome. Nature, 520(7545), 82.

Ginter, M., 1990. Late Famennian shark teeth from the Holy Cross Mts, Central Poland. Acta Geologica Polonica, 40, 69-81.

Ginter, M., Hairapetian, V., and Klug, C., 2002. Famennian chondrichthyans from the shelves of North Gondwana. Acta Geologica Polonica, 52(2), 169215.

Ginter, M., Hampe, O., and Duffi n, C. J., 2010. Chon-drichthyes: Paleozoic Elasmobranchii: teeth, in: Schultze, H. (Ed.), Handbook of Paleoichthyology, 3D, 168 p.

Grogan, E. D., and Lund, R., 2008. A basal elas-mobranch, Thrinacoselache gracia n. gen and sp.,(Thrinacodontidae, new family) from the Bear Gulch Limestone, Serpukhovian of Montana, USA. Journal of Vertebrate Paleontology, 28(4), 970-988.

Halamski, A. T., and Baliński, A., 2013. Middle De-vonian brachiopods from the southern Maїder (eastern Anti-Atlas, Morocco). Annales Societatis Geologorum Poloniae, 83(4), 243-307.

Hampe, O., 2003. Revision of the Xenacanthida (Chondrichthyes: Elasmobranchii) from the Car-boniferous of the British Isles. Transaction of the Royal Society of Edingburgh, Earth Sciences, 93, 191-237.

Hanke, G.F., Wilson, M.V.H., and Lindoe, L.A., 2001. New species of Silurian acanthodians from the Mackenzie Mountains, Canada. Canadian Journal of Earth Sciences, 38, 1517-1529. doi:10.1139/e01-039.

Harris, J. E., 1938a. The dorsal fi n spine of Cladose-lache. Scientifi c Publications of the Cleveland Mu-seum of Natural History, 8, 1-6.

Harris, J. E., 1938b. The neurocranium and jaws of Cladoselache. Scientifi c Publications of the Cleve-land Museum of Natural History, 8, 7-12.

Hartenfels, S. 2011. Die globalen Annulata-Events

21

Introduction

und die Dasberg-Krise (Famennium, Oberdevon) in Europa und Nord-Afrika - hochaufl ösende Co-nodonten-Stratigraphie, Karbonat-Mikrofazies, Paläoökologie und Paläodiversität. Münstersche Forschungen zur Geologie und Paläontologie, 105, 1-527.

Hartenfels, S. and Becker, R. T. 2009. Timing of the global Dasberg Crisis-implications for Famennian eustasy and chronostratigraphy. Palaeontographi-ca Americana, 63, 71-97.

Hartenfels, S. and Becker, R.T. 2016a. The global An-nulata Events: review and new data from the Rheris Basin (northern Tafi lalt) of SE Morocco, in: Beck-er, R. T., Königshof, P., Brett, C. E. (Eds.), Devo-nian Climate, Sea Level and Evolutionary Events. Geological Society, London, Special Publications, 423, http://doi.org/10.1144/SP423.14

Hartenfels, S. and Becker, R. T., 2016b. Age and cor-relation of the transgressive Gonioclymenia Lime-stone (Famennian, Tafi lalt, eastern Anti-Atlas, Mo-rocco). Geological Magazine, 1-44.

Heidtke, U. H. J., 1982. Der Xenacanthide Orthacant-hus senckenbergianus aus dem pfälzischen Rotlie-genden (Unter-Perm). Pollichia, 70, 65-86.

Heidtke, U. H. J., 1999. Orthacanthus (Lebachacant-hus) senckenbergianus Fritsch 1889 (Xenacanthi-da: Chondrichthyes): revision, organisation und phylogenie. Freiberger Forschungsheft, 481, 63-106.

Heidtke, U. H. J., and Krätschmer K., 2001. Gladba-chus adentatus nov. gen. et sp., ein primitiver Hai aus dem Oberen Givetium (Oberes Mitteldevon) der Bergisch Gladbach - Paffrath-Mulde (Rheini-sches Schiefergebirge). Mainzer geowissenschaftli-che Mitteilungen, 30, 105-122.

Heidtke, U. H. J., Schwind, C., and Krätschmer K., 2004. Über die Organisation des Skelettes und die verwandschaftlichen Beziehungen der Gattung Tri-odus Jordan 1849 (Elasmobranchii: Xenacanthida). Mainzer geowissenschaftliche Mitteilungen, 32, 9-54.

Hotton, N., 1952. Jaws and teeth of American xena-canth sharks. Journal of Paleontology, 26, 489-500.

House, M.R. 1985. Correlation of mid-Palaeozoic am-monoid evolutionary events with global sedimenta-ry perturbations. Nature, 313, 1722.

House, M.R., 2002. Strength, timing, setting and cause of mid-Palaeozoic extinctions. Palaeogeography, Palaeoclimatology, Palaeoecology, 181, 525.

Hryniewicz, K., Jakubowicz, M., Belka, Z., Dopier-alska, J., and Kaim, A., 2017. New bivalves from a Middle Devonian methane seep in Morocco: the oldest record of repetitive shell morphologies among some seep bivalve molluscs. Journal of Sys-

tematic Palaeontology, 15(1), 19-41.

Itano, W. M., 2015. An abraded tooth of Edestus (Chondrichthyes, Eugeneodontiformes): Evidence for a unique mode of predation. Transactions of the Kansas Academy of Science, 118(1-2), 1-9.

Itano, W. M. 2018. A tooth whorl of Edestus heinrichi (Chondrichthyes, Eugeneodontiformes) displaying progressive macrowear. Transactions of the Kansas Academy of Science, 121(1-2), 125-133.

Itano, W. M., 2014. Edestus, the strangest shark? First report from New Mexico, North American paleo-biogeography, and a new hypothesis on its method of predation. The Mountain Geologist, 51(3), 201-221.

Janvier, P., and Suarez-Riglos, M., 1986. The Silurian and Devonian vertebrates of Bolivia. Bulletin de l’Institut français d’Études andines, 15(3-4), 73-114.

Jessen, H., 1968. Moythomasia nitida Gross und M. cf. striata Gross, Devonische palaeonisciden aus dem oberen Plattenkalk der Bergisch-Gladbach-Paf-frather Mulde (Rheinisches Schiefergebirge). Pa-laeontographica Abteilung A, 128, 87–114.

Joachimski, M.M., Breisig, S., Buggisch, W., Talent, J.A., Mawson, R., Gereke, M., Morrow,

J.R., Day, J., Weddige, K., 2009. Devonian climate and reef evolution: insights from

oxygen isotopes in apatite. Earth Planet Science Let-ters, 284, 599-609.

Joachimski, M. M., Buggisch, W., 2002. Conodont ap-atite δ18O signatures indicate climatic cooling as a trigger of the Late Devonian mass extinction. Geol-ogy, 30(8), 711714.

Kaiser, S. I., Aretz, M., Becker, R. T., 2015. The global Hangenberg Crisis (Devonian-Carboniferous tran-sition): review of a fi rst-order mass extinction. In Becker, R. T., Königshof, P., Brett, C. E. (Eds.), De-vonian climate, sea level and evolutionary events. Geological Society of London, Special Publica-tions, pp. 387437.

Kaiser, S. I., Becker, R. T., Steuber, T., and Aboussalam S. Z. 2011. Climate-controlled mass extinctions, facies, and sea-level changes around the Devoni-an-Carboniferous boundary in the eastern Anti-At-las (SE Morocco). Palaeogeography, Palaeoclima-tology, Palaeoecology, 310, 340364.

Kaiser, S. I., Steuber, T., Becker, T., 2008. Environ-mental change during the Late Famennian and Early Tournaisian (Late Devonian-Early Carbon-iferous): implications from stable isotopes and conodont biofacies in southern Europe. Geological Journal, 42, 241260.

Kaiser, S. I., Steuber, T., Becker, R. T., Joachimski, M.

22

Introduction

M., 2006. Geochemical evidence for major envi-ronmental change at the Devonian-Carboniferous boundary in the Carnic Alps and the Rhenish Mas-sif. Palaeogeography, Palaeoclimatology, Palaeo-ecology, 240(1), 146-160.

Karatajūtė-Talimaa, V., 1973. Elegestolepis grossi gen. et sp. nov., ein neues Typ der Placoidschuppe aus dem oberen Silur der Tuwa. Palaeontographica Abteilung A, 143, 35-50.

Karatajūtė-Talimaa, V., 1995. The Mongolepidida: scale structure and systematic position. Geobios, MS, 19, 35-37.

Karatajūtė-Talimaa, V., and Novitskaya, I., 1992. Teslepis, a new mongolepid elasmobranchian fi sh from the Lower Silurian of Mongolia. Paleontolo-gischeskii Zhurnal, 4, 36-47.

Karatajūtė-Talimaa, V., and Smith, M.M. 2002. Ear-ly acanthodians from the Lower Silurian of Asia. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 93, 277 299. doi:10.1017/S0263593300000444

Karatajūtė-Talimaa, V., Rozman, K. H. S., and Sodov, Z.H., 1990. Mongolepis, a new elasmobranch ge-nus from the Lower Silurian of Mongolia. Paleon-tologicheskii Zhurnal, 1, 76-86.

Kaufmann, B. 1998. Facies analysis, stratigraphy and diagenesis of Middle Devonian reef- and mud-mounds in the Mader (eastern Anti-Atlas, Moroc-co). Acta Geologica Polonica , 48(1), 43-106.

Karpinski, A. P., 1899A. Ueber die Reste von Edestiden und die neue Gattung Helicoprion. Verhdl. Kaiser. Russ. Miner. Ges. St. Petersburg, 36(2), 1-111.

Klug, C. 2002. Quantitative stratigraphy and taxonomy of late Emsian and-Eifelian ammonoids of the east-ern Anti-Atlas (Morocco). Courier Forschungsins-titut Senckenberg, 238, 1-109.

Klug, C., Frey, L., Korn, D., Jattiot, R., and Rücklin, M. 2016. The oldest Gondwanan cephalopod man-dibles (Hangenberg Black Shale, Late Devonian) and the mid-Palaeozoic rise of jaws. Palaeontolo-gy, 59(5), 611-629.

Klug, C., Kröger, B., Korn, D., Rücklin, M., Schemm-Gregory, M., De Baets, K., and Mapes, R. H. 2008. Ecological change during the early Emsian (Devonian) in the Tafi lalt (Morocco), the origin of the Ammonoidea, and the fi rst African pyrgocystid edrioasteroids, machaerids and phyllo-carids. Palaeontographica Abteilung A, 283(4-6), 83-176.

Klug, C., Rücklin, M., Meyer-Berthaud, B., and Soria, A., 2003. Late Devonian pseudoplanktoniccrinoids from Morocco. Neues Jahrbuch für Geologie und Mineralogie, 3, 153-163.

Klug, C., Schulz, H., and De Baets, K., 2009. Red De-vonian trilobites with green eyes from Morocco and the silicifi cation of the trilobite exoskeleton. Acta Palaeontologica Polonica, 54(1), 117-123.

Korn, D. 1999. Famennian Ammonoid Stratigraphy of the Ma’der and Tafi lalt (Eastern Anti-Atlas, Moroc-co). In: R. Feist, J.A. Talent and A. Daurer (Eds), North Gondwana: Mid-Paleozoic Terranes, Stratig-raphy and Biota. Abhandlungen der Geologischen Bundesanstalt, 54, 147-179.

Korn, D., Belka, Z., Fröhlich, S., Rücklin, M., and Wendt, J. 2004. The youngest African clymeniids (Ammonoidea, Late Devonian)-failed survivors of the Hangenberg Event. Lethaia, 37(3), 307-315.

Korn, D. and Bockwinkel, J., 2017. The genus Gonio-clymenia (Ammonoidea; Late Devonian) in the An-ti-Atlas of Morocco. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 285(1), 97-115.

Korn, D., Bockwinkel, J. and Ebbighausen, V., 2014. Middle Famennian (Late Devonian) ammonoids from the Anti-Atlas of Morocco, 1. Prionoceras. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 272(2), 167204.

Korn, D., Bockwinkel, J. and Ebbighausen, V., 2015a. The Late Devonian ammonoid Mimimitoceras in the Anti-Atlas of Morocco. Neues Jahrbuch für Ge-ologie und Paläontologie, Abhandlungen, 275(2), 125-150.

Korn, D., Bockwinkel, J. and Ebbighausen, V., 2015b. Middle Famennian (Late Devonian) ammonoids from the Anti-Atlas of Morocco, 2. Sporadocera-tidae. Neues Jahrbuch für Geologie und Paläonto-logie, Abhandlungen, 278(1), 4777.

Korn, D., Bockwinkel, J. and Ebbighausen, V., 2016a. The late Famennian tornoceratid ammonoids in the Anti-Atlas of Morocco. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 281(2), 201220.

Korn, D., Bockwinkel, J. and Ebbighausen, V., 2016b. Middle Famennian (Late Devonian) ammonoids from the Anti-Atlas of Morocco. 3. Tornoceratids. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 281(3), 267281.

Korn, D., and Klug, C., 2002. Ammoneae Devonicae. Fossilium Catalogus. I. Animalia 138. 375 pp. Backhuys Publishers (Leiden, Netherlands).

Kříž, J., 2000. Lochkovian bivalves of Bohemian type from the eastern Anti-Atlas (Lower Devonian, Mo-rocco). Senckenbergiana lethaea, 80(2), 485-523.

Kröger, B., 2008. Nautiloids before and during the or-igin of ammonoids in a Siluro-Devonian section in the Tafi lalt, Anti-Atlas, Morocco., Special Papers in Palaeontology, 79, 1-110.

23

Introduction

Lane, J. A., 2010. Morphology of the braincase in the Cretaceous hybodont shark Tribodus linnae (Chon-drichthyes: Elasmobranchii), based on CT scan-ning. American Museum Novitates, 2758, 1-70.

Lane, J. A., and Maisey, J. G., 2009. Pectoral anato-my of Tribodus limae (Elasmobranchii: Hybodon-tiformes) from the Lower Cretaceous of Northeast-ern Brazil. Journal of Vertebrate Paleontology, 29, 25-38.

Lane, J. A., and Maisey, J. G., 2012. The visceral skeleton and jaw suspension in the durophagous hybodontid shark Tribodus limae from the Lower Cretaceous of Brazil. Journal of Paleontology, 86, 886-905.

Lebedev, O. A., and Clack, J. A., 1993. Upper Devoni-an tetrapods from Andreyevka, Tula Region, Rus-sia. Palaeontology, 36, 721-734.

Lebedev, O. A., and Coates, M. I., 1995. The postcra-nial skeleton of the Devonian tetrapod Tulerpeton curtum Lebedev. Zoological Journal of the Linnean Society, 114, 307-348.

Lehman, J. P., 1956. Les Arthrodires du Dévonien supé-rieur du Tafi lalt (Sud Marocain). Notes et Mémoires du Service Géologique du Maroc, 129, 170.

Lehman, J. P., 1964. A propos de quelques Arthrodires et Ichthyodorulites sahariens. Mémoire IFAN, 68, 193-200.

Lehman, J. P., 1976. Nouveaux poissons fossiles du Dévonien du Maroc. Annales de Paléontologie Ver-tébrés, 62, 134.

Lehman, J. P., 1977. Sur la présence d’un Ostéolé-piforme dans le Dévonien supérieur du Tafi lalt. Compte-Rendus de l’Académie des Sciences, 285D, 151153.

Lehman, J. P., 1978. A propos de deux poissons du Fa-mennien du Tafi lalt. Annales de Paléontologie Ver-tébrés, 64, 143152.

Lelièvre, H., Janvier, P., 1986. L’Eusthénopteridé (Osteichthyes, Sarcopterygii) du Famennian (Dé-vonien supérieur) du Tafi lalt (Maroc): nouvelle description. Bulletin du Muséum National d’His-toire naturelle, 4e Série, Section C, Sciences de la Terre, Paléontologie, Géologie, Minéralogie, 3, 351365.

Lelièvre, H., Janvier, P., 1988. Un Actinistien (Sar-copterygii, Vertebrata) dans le Dévonien supérieur du Maroc. Compte-Rendus de l’Académie des Sciences, Paris 307, 14251430.

Lelièvre, H., Janvier, P., Blieck, A., 1993. Silurian-De-vonian vertebrate biostratigraphy of western Gond-wana and related terranes (South America, Africa, Armorica-Bohemia, Middle East). Palaeozoic vertebrate biostratigraphy and biogeography, pp.

139173.

Long, J. A., 1983. A new diplacanthoid acanthodian from the Late Devonian of Victoria. Association of Australasian Palaeontologists Memoir, 1, 51 – 65.

Long, J. A., 1991. The long history of Australian fossil fi shes. In: Vickers-Rich P., Monaghan J. M., Baird R. F. and Rich T. H. (eds). Vertebrate Palaeontol-ogy of Australasia, pp. 337 – 428. Pioneer Design Studio, Lilydale.

Long, J. A., Large, R. R., Lee, M. S., Benton, M. J., Danyushevsky, L. V., Chiappe, L. M., Halpin, J. A., Cantrill, D., Lottermoser, B., 2015. Severe seleni-um depletion in the Phanerozoic oceans as a factor in three global mass extinction events. Gondwana Research, 36, 209218.

Long, J.A., Mark-Kurik, E., Johanson, Z., Lee, M.S.Y.,Young, G.C., Min, Z., Ahlberg, P.E., New-man, M., Jones, R., Blaauwen, J.d., Choo, B., and Trinajstic, K. 2015. Copulation in antiarch placo-derms and the origin of gnathostome internal fertil-ization. Nature, 517, 196-199.

Long, J. A., Trinajstic, K., 2010. The Late Devonian Gogo Formation Lägerstatte of Western Australia: exceptional early vertebrate preservation and diver-sity. Annual Review of Earth and Planetary Scienc-es, 38, 255279.

Lubeseder, S., Rath, J., Rücklin, M., Messbacher, R., 2010. Controls on Devonian hemi-pelagic lime-stone deposition analyzed on cephalopod ridge to slope sections, Eastern Anti-Atlas, Morocco. Fa-cies, 56, 295-315.

Lund, R., 1985. The morphology of Falcatus falcatus (St. John and Worthen), a Mississippian stethacan-thid chndrichthyan from the Bear Gulch Limestone of Montana. Journal of Vertebrate Paleontology, 5, 1-19.

Lund, R., 1986. On Damocles serratus nov. gen. et sp., (Elasmobranchii: Cladodontida) from the Upper Mississippian Bear Gulch Limestone of Montana. Journal of Vertebrate Paleontology, 6, 12-19.

Lund, R., and Grogan, E. D., 1997. Relationships of the Chimaeriformes and the basal radiation of the Chondrichthyes. Reviews in Fish Biology and Fish-eries, 7(1), 65-123.

Lund, R., Greenfest-Allen, E., and Grogan, E. D., 2012. Habitat and diversity of the Bear Gulch fi sh: Life in a 318 million year old marine Mississippian bay. Palaeogeography, Palaeoclimatology, Palae-oecology, 342, 1-16.

Lund, R., Greenfest-Allen, E., and Grogan, E. D., 2015. Ecomorphology of the Mississippian fi shes of the Bear Gulch Limestone (Heath formation, Montana, USA). Environmental biology of fi shes, 98(2), 739-754.

24

Introduction

Mader, H., 1986. Schuppen und Zähne von Acantho-diern und Elasmobranchiern aus dem Unter-Devon Spaniens (Pisces). Göttinger Arbeiten zur Geologie und Paläontologie, 28, 1-59.

Maisey, J.G., 1981. Studies on Paleozoic Selachian Genus Ctenacanthus Agassiz No. 1. Historical Re-view and Revised Diagnosis of Ctenacanthus, With a List of Referred Taxa. American Museum Novi-tates, 2718, 1-22.

Maisey, J.G., 1982a. Studies on the Paleozoic Sela-chian genus Ctenacanthus Agassiz. No. 2, Byth-iacanthus St. John and Worthen, Amelacanthus, new genus, Eunemacanthus St. John and Worthen, Sphenacanthus Agassiz, and Wodnika Münster. American Museum novitates, 2722.

Maisey, J. G., 1982b. The anatomy and interrelation-ships of Mesozoic hybodont sharks. Am. Mus. No-vit. 2724, 1-48.

Maisey, J. G., 1983. Cranial anatomy of Hybodus basanus Egerton from the Lower Cretaceous of England. American Museum Novitates. 2758, 1-64.

Maisey, J.G., 1984a. Studies on the Paleozoic sela-chian genus Ctenacanthus Agassiz. No. 3, Nominal species referred to Ctenacanthus. American Muse-um novitates, 2774.

Maisey, J. G., 1984b. Higher elasmobranch phylogeny and biostratigraphy. Zoological Journal of the Lin-nean Society, 82(1-2), 33-54.

Maisey, J. G., 1989a. Hamiltonichthys mapesi g. & sp. nov. (Chondrichthyes; Elasmobranchii), from the Upper Pennsylvanian of Kansas. American Muse-um Novitates, 2931, 1-42.

Maisey, J. G., 1989b. Visceral skeleton and muscula-ture of a Late Devonian shark. Journal of Verte-brate Paleontology, 9, 174-190.

Maisey, J. G., 2009. The spine-brush complex in sym-moriiform sharks (Chondrichthyes; Symmorii-formes), with commenst on dorsal fi n modularity. Journal of Vertebrate Paleontology, 29, 14-24.

Maisey, J. G., and Anderson, M. E., 2001. A primitive chondrichthyan braincase from the Early Devonian of South Africa. Journal of Vertebrate Paleontolo-gy, 21, 702-713.

Maisey, J. G., and de Carvalho, M. R., 1997. A new look at old sharks. Nature 385, 779-780.

Maisey, J. G., Miller, R. and Turner, S., 2009. The braincase of the chondrichthyan Doliodus from the Lower Devonian Campbellton Formation of New Brunswick, Canada. Acta Zoologica, 90, 109-122.

Maisey, J. G., Miller, R., Pradel, A., Denton, J. S. S., Bronson, A. and Janvier, P., 2017 Pectoral morphol-ogy in Doliodus: bridging the ‘acanthodian’-chon-drichthyan divide. American Museum Novitates,

3875, 1-15.

Maisey, J. G., Naylor, G. J., and Ward, D. J., 2004. Me-sozoic elasmobranchs, neoselachian phylogeny and the rise of modern elasmobranch diversity. Mesozo-ic fi shes, 3, 17-56.

McGhee, G. R., 1988. The Late Devonian extinction event: evidence for abrupt ecosystem collapse. Pa-leobiology, 14(3), 250257.

McGhee Jr., G. R., 2001. The `multiple impacts hy-pothesis` for mass extinction: a comparison of the Late Devonian and the late Eocene. Palaeogeog-raphy, Palaeoclimatology, Palaeoecology, 176, 4758.

McGhee Jr., G.R., 2014. When the Invasion of Land Failed. The Legacy of the Devonian Extinctions. Columbia University Press, New York (317 pp.).

Miller, R. F., Cloutier, R. and Turner, S., 2003. The oldest articulated chondrichthyan from the Early Devonian period. Nature 425, 501-504.

Neugebauer, J. (1988), The Variscan plate tectonic evo-lution: An improved Iapetus model. Schweizerische Mineralogische und Petrographische Mitteilungen, 68, 313-333.

Novitskaya, L. I. and Karatajūtė-Talimaa, V. N., 1986. Remarks about the cladistic analysis in connection with myopterygian hypothesis and the problem of the origin of gnathostomes. pp. 102-125. In Vorob-yeva, E. and Lebedkina, N. (eds): Morfologiya i evolyutsiya zhivotnykh [Morphology and evolu-tion of animals]. Nauka, Moscow, 246 pp.

Oelofsen, B. W., 1986. in Indo-Pacifi c Fish Biology: Proceedings of the Second International Confer-ence on Indo-Pacifi c Fishes. (eds Uyeno, T., Arai, R., Taniuchi, T., Matsuura, K.) 107-124 (Ichthyo-logical Society of Japan, Tokyo).

Retallack, G. J., 1997. Early forest soils and their role in Devonian global change. Science, 276(5312), 583-585.

Riquier, L., Tribovillard, N., Averbuch, O., Devlee-schouwer, X., Riboulleau, A., 2006. The Late Fras-nian Kellwasser horizons of the Harz Mountains (Germany): two oxygendefi cient periods resulting from different mechanisms. Chemical Geology, 233 (1-2), 137-155.

Rücklin M., 2010. A new Frasnian placoderm assem-blage from the eastern Anti-Atlas, Morocco, and its palaeobiogeographical implications. Palaeoworld 19, 8793.

Rücklin M., 2011. First selenosteid placoderms from the eastern Anti-Atlas of Morocco; osteology, phy-logeny and palaeogeographical implications. Pa-laeontology 54, 2562.

Rücklin, M., Clément, G., 2017. Une revue des Placo-

25

Introduction

dermes et Sarcoptérygiens du Dévonien du Maroc, in: Zouhri, S. (ed), Paléontologie des vertébrés du Maroc: état des connaissance, Mémoires de la So-ciété Géologique de France 180, p. 624.

Rücklin, M., Long, J. A., Trinajstic, K., 2015. A new selenosteid arthrodire (‘Placodermi’) from the Late Devonian of Morocco. Journal of Vertebrate Pale-ontology 35(2), e908896, 113.

Sallan, L. C., Coates, M. I., 2010. End Devonian ex-tinction and a bottleneck in the early evolution of modern jawed vertebrates. Proceedings of the Na-tional Academy of Science 107(22), 1013110135.

Sandberg, C.A., Morrow, J.R., Ziegler, W., 2002. Late Devonian sea-level changes, catastrophic events, and mass extinctions. In Koeberl, C., MacLeod, K.G. (Eds.), Catastrophic Events and Mass Extinc-tions: Impacts and Beyond, Geological Society of America, Special Papers, 356, 473-487.

Sansom, I.J., Aldridge, R.J., and Smith, M.M., 2000. A microvertebrate fauna from the Llandovery of South China. Transactions Royal Society of Edin-burgh, 90, 255-272.

Sansom, I. J., Davies, N. S., Coates, M. I., Nicoll, R. S., and Ritchie, A., 2012. Chondrichthyan-like scales from the Middle Ordovician of Australia. Palaeon-tology, 55(2), 243-247.

Sansom, I. J., Smith, M. M. and Smith, M. P., 1996. Scales of thelodont and shark-like fi shes from the Ordovician of Colorado. Nature, 379, 628-670.

Sartenaer, P., 1998. The presence in Morocco of the late Famennian genus Hadyrhyncha Havlíĉek, 1979 (rhynchonellid, brachiopod). Bulletin de l`Institute Royal des sciences naturelles de belgique, sciences de la terre, 68, 115120.

Sartenaer, P., 1999. Tetragonorhynchus, new late Famennian rhynchonellid genus from Maïder, southern Morocco, and Tetragonorhynchidae n. fam. Bulletin de l’institute royal des sciences natu-relles de belgique, sciences de la terre, 69, 6775.

Sartenaer, P., 2000. Phacoiderhynchus, a new middle Famennian rhynchonellid genus from the Anti-At-las, Morocco, and Phacoiderhynchidae n. fam. Bul-letin de l’institute royal des sciences naturelles de belgique, sciences de la terre, 70, 7588.

Schaeffer, B., 1967. Comments on elasmobranch evo-lution. In P. W. Gilbert, R. F. Mathewson, and D. P. Rall (eds.), Sharks, skates and rays, pp. 3-35. Johns Hopkins Press, Baltimore, Maryland.

Schaeffer, B., and Williams, M., 1977. Relationships of fossil and living elasmobranchs. American Zool-ogist, 17(2), 293-302.

Schaeffer, B., 1981. The xenacanth shark neurocrani-um, with comments on elasmobranch monophyly.

Bulletin of the American Museum of Natural His-tory, 169, 1-66.

Scotese, C. R., 2001. Atlas of Earth History, Volume 1, Paleogeography, PALEOMAP Project, Arlington, Texas, 52 pp.

Sepkoski, J. J. Jr, 2002. A compendium of fossil ma-rine animal genera. Bulletin of American Paleon-tology, 363, 1–560.

Shubin, N. H., Daeschler, E. B., and Coates, M. I., 2004. The early evolution of the tetrapod humerus. Science, 304, 90-93.

Solér-Gijon, R., and Hampe, O., 1998. Evidence of Triodus Jordan 1849 (Elasmobranchii: Xenacan-thidae) in the Lower Permian of the Autun basin (Muse, France). Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 1998, 335-348.

Stein, W. E., Berry, C. M., Hernick, L. V., and Man-nolini, F., 2012. Surprisingly complex community discovered in the mid-Devonian fossil forest at Gil-boa. Nature, 483(7387), 78.

Struve, W., 1990. Beiträge zur Kenntnis der Phacopi-na (Trilobita), 18: Die Riesen-Phacopiden aus dem Ma‘der, SEmarokkanische Prä-Sahara. Sencken-bergiana Lethaea, 75 (1/2), 77-129.

Termier, H., 1936. Etudes géologiques sur le Maroc central et le Moyen atlas septentrional. Notes et Mémoires Service des Mines et de la carte géolo-gique du Maroc 33, 1566p.

Tessitore, L., Schemm-Gregory, M., Korn, D., Wild, F. R., Naglik, C., & Klug, C. (2013). Taphonomy and palaeoecology of the green Devonian gypidulid brachiopods from the Aferdou El Mrakib, eastern Anti-Atlas, Morocco. Swiss Journal of Palaeontol-ogy, 132(1), 23-44.

Turner, S., 1997. “Dittodus” species of Eastman 1899 and Hussakopf and Bryant 1918 (Mid to Late De-vonian). Modern Geology, 21, 87-119.

Walliser, O. H., 1996. Global events in the Devoni-an and Carboniferous. In Walliser, O. H., Global events and event stratigraphy in the Phanerozoic, 225250.

Webster, G. D., Becker, R. T., and Maples, C. G., 2005. Biostratigraphy, paleoecology, and taxonomy of Devonian (Emsian and Famennian) crinoids from southeastern Morocco. Journal of Paleontology, 79(6), 1052-1071.

Wendt, J., 1985. Disintegration of the continental mar-gin of northwestern Gondwana: late Devonian of the eastern Anti-Atlas (Morocco). Geology, 13, 815-818.

Wendt, J., 1995. Shell directions as a tool in palaeocur-rent analysis. Sedimentary Geology, 95, 161-186.

26

Introduction

Wendt, J. and Belka, Z. 1991. Age and depositional environment of Upper Devonian (early Frasnian to early Famennian) black shales and limestones (Kellwasser facies) in the eastern Anti-Atlas, Mo-rocco. Facies, 25, 51-90.

Wendt, J., Kaufmann, B., Belka, Z., Klug, C., and Lu-beseder, S., 2006. Sedimentary evolution of a Pa-laeozoic basin and ridge system: the Middle and Upper Devonian of the Ahnet and Mouydir (Alge-rian Sahara). Geological Magazine, 143 (3), 269-299.

Williams, M. E., 2001. Tooth retention in cladodont sharks: with a comparison between primitive grasping and swallowing, and modern cutting and gouging feeding mechanisms. Journal of Verte-brate Paleontology, 21, 214-226.

Williams, M. E. 1985. The “cladodont level” sharks of the Pennsylvanian Black Shales of central North America. Palaeontographica A, 190, 83-158.

Woodward, A. S., and White, E. I., 1938. The dermal tubercles of the Upper Devonian shark, Cladose-lache. Annals and Magazine of Natural History, 11, 367-368.

Young, G. C., 1982. Devonian sharks from South-East-ern Australia and Antarctica. Palaeontology, 25, 817-843.

Young, G. C., 1989a. The Aztec fi sh fauna of southern Victoria Land-evolutionary and biogeographic sig-nifi cance. In: Crame J. A. (ed.) Origins and Evolu-tion of the Antarctic Biota, pp. 43 – 62. Geological Society of London Special Publication , 47.

Young, G.C., 1989b. New occurrences of culmacan-thid acanthodians (Pisces, Devonian) from Antarc-tica and southeastern Australia. Proceedings of the Linnean Society of New South Wales, 111, 12– 25.

Young, G. C., 1997. Ordovician microvertebrate re-mains from the Amadeus Basin, central Australia. Journal of Vertebrate Paleontology, 17, 1-25.

Young G.C., 2000. Replacement name for Areyonga Young 1997 (preoccupied name). Journal of Verte-brate Paleontology, 20, 611.

Young, G.C., 2007. Devonian formations, vertebrate faunas and age control on the far south coast of New South Wales and adjacent Victoria. Australian Journal of Earth Sciences, 54(7), 991-1008. DOI: 10.1080/08120090701488313

Zangerl, R., 1981. Chondrichthyes I: Paleozoic Elas-mobranchii. In: Schultze, H. P. (ed.), Handbook of Paleoichthyology 3A, 115 pp. Gustave Fischer, Stuttgart, New York.

Zangerl, R., 1984. On the microscopic anatomy and possible function of the spine “brush”complex of Stethacanthus (Elasmobranchii: Symmoriida). Journal of Vertebrate Paleontology, 4(3), 372-378. DOI: 10.1080/02724634.1984.10012016

Zangerl, R., 1990. Two new stethacanthid sharks (Stethacanthidae, Symmoriida) from the Pennsyl-vanian of Indiana, USA. Palaeontographica A, 213, 115-141.

Zangerl, R. and Case, G. R., 1976. Cobelodus aculeatus (Cope), ananacanthous shark from Pennsylvanian black shales of North America. Palaeontographica A, 154, 107-157.

Zhu, M. 1998. Early Silurian sinacanths (Chondrich-thyes) from China. Palaeontology, 41, 157-171.

Zhu, M., Yu, X., Ahlberg, P.E., Choo, B., Lu, J., Qiao, T., Qu, Q., Zhao, W., Jia, L., Blom, H., and Zhu, Y.A., 2013. A Silurian placoderm with osteich-thyan-like marginal jaw bones. Nature, 502, 188-193.

Zhu, M., Ahlberg, P. E., Zhao, W., and Jia, L., 2002. First Devonian tetrapod from Asia. Nature, 420, 760-761.

Žigaitė, E.Z., and Karatajūtė-Talimaa, V., 2008. New genus of chondrichthyans from the Silurian-Devo-nian boundary deposits of Tuva. Acta Geologica Polonica, 58, 127-131.

CHAPTER I

Late Devonian and Early Carboniferous alpha diversity,

ecospace occupation, vertebrate assemblages and bio-events

of southeastern Morocco

Linda Frey, Martin Rücklin, Dieter Korn and Christian Klug

Published in:

Palaeogeography, Palaeoclimatology, Palaeoecology, 496 (2018), 1-17

https://doi.org/10.1016/j.palaeo.2017.12.028

29

Chapter I: Alpha Diversity and Palaeoecology

Contents lists available at ScienceDirect

Palaeogeography, Palaeoclimatology, Palaeoecology

journal homepage: www.elsevier.com/locate/palaeo

Late Devonian and Early Carboniferous alpha diversity, ecospace

occupation, vertebrate assemblages and bio-events of southeastern Morocco

Linda Freya,⁎

, Martin Rücklinb, Dieter Kornc, Christian Kluga

a Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, SwitzerlandbNaturalis Biodiversity Center, Postbus 9517, 2300, RA, Leiden, The NetherlandscMuseum für Naturkunde Berlin, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, D-10115 Berlin, Germany

A R T I C L E I N F O

Keywords:

Fossillagerstätte

Famennian

Gnathostomes

Invertebrates

Palaeoecology

Sea level

A B S T R A C T

The Late Devonian was a time of dramatic environmental perturbations affecting marine ecosystems. Both the

Kellwasser (latest Frasnian) and the Hangenberg crises (latest Famennian) are primarily reported as phases of

drastic decreases in marine diversity while the Hangenberg Crisis is also described as a bottleneck in vertebrate

evolution. Fossil-bearing localities with Upper Devonian strata are of great interest to assess variations in the

effects of environmental perturbations on biodiversity. For this purpose, we examined changes in alpha diversity

and ecospace utilization of 21 Famennian (Late Devonian) and early Tournaisian (Early Carboniferous) in-

vertebrate associations containing 9828 specimens from Madène el Mrakib and Aguelmous (southern Maïder

Basin, northeastern Anti-Atlas, Morocco), where some layers yield exceptionally preserved gnathostome re-

mains. Both the invertebrate and vertebrate associations contain predominantly opportunistic and pelagic taxa

indicating oxygen depletion near the seafloor in this region. Nevertheless, the ecospace extension was fluctuating

and correlated with regional and/or global sea-level changes and oxygenation of bottom waters. In the Maïder

Basin, the ecospace was depleted after and during several bio-events such as the Kellwasser and Hangenberg

crises, the Annulata event (middle Famennian) as well as during the early Tournaisian. Abiotic as well as biotic

changes (instability of the invertebrate ecosystem) are considered to have influenced Famennian vertebrate

diversity because they were more or less directly dependent on invertebrates as a food source.

1. Introduction

Fundamental environmental perturbations and evolutionary

changes in vertebrates and invertebrates were widely reported to have

occurred during the Late Devonian (e.g. House, 1985; McGhee, 1988;

Walliser, 1996; Algeo et al., 1995, 2001; Algeo and Scheckler, 1998;

Caplan and Bustin, 1999; Murphy et al., 2000; Joachimski and

Buggisch, 2002; Goddéris and Joachimski, 2004; Racki, 2005; Bond and

Wignall, 2008; Sallan and Coates, 2010; Sallan and Galimberti, 2015;

Long et al., 2015). Two biotic crises that strongly affected global biota

were the Kellwasser and Hangenberg crises (Buggisch, 1991; Kaiser

et al., 2006, 2008, 2015; Carmichael et al., 2015; Becker et al., 2016);

in addition small-scale events such as the Condroz (Becker, 1993),

Annulata (Becker and House, 1997, 2000; Sandberg et al., 2002; Korn,

2002, 2004; Racka et al., 2010; Hartenfels and Becker, 2016a) and

Dasberg events (Hartenfels and Becker, 2009; Hartenfels, 2011; Kaiser

et al., 2011) have been recognized in Frasnian and Famennian succes-

sions (House, 1985, 2002; Walliser, 1996; Table 1). Both the Kellwasser

Crisis (latest Frasnian) and the Hangenberg Crisis (end-Devonian)

caused severe losses of global diversity of many marine and terrestrial

biotic groups (Newell, 1952, 1956, 1963; Raup and Sepkoski, 1982;

McGhee, 1996; McGhee Jr, 2001, 2014; Alroy, 2010; McGhee Jr et al.,

2013; Sallan and Coates, 2010; Friedman and Sallan, 2012; Sallan and

Galimberti, 2015). However, causes for ecosystem changes and di-

versity loss during the Late Devonian are still highly debated (e.g.

Buggisch, 1991; Algeo et al., 1995, 2001; Algeo and Scheckler, 1998;

Sandberg et al., 2002; Riquier et al., 2006; Long et al., 2015) and

concerning vertebrates, this time interval was mainly studied via global

diversity curves (e.g. Sallan and Coates, 2010; Friedman and Sallan,

2012; Sallan and Galimberti, 2015). Therefore, a regional study on the

vertebrate ecosystem including other organisms such as invertebrates

from a locality with detailed stratigraphical and sedimentological in-

formation is needed. The Maïder Basin of the eastern Anti-Atlas is

suitable for this purpose.

The eastern Anti-Atlas of Morocco is well-known for its highly fos-

siliferous outcrops of Devonian marine sedimentary rocks. In recent

years (e.g., Klug et al., 2008, 2016), some stratigraphic intervals of

several localities became known for their Fossillagerstätten qualities

https://doi.org/10.1016/j.palaeo.2017.12.028

Received 30 June 2017; Received in revised form 21 December 2017; Accepted 22 December 2017

⁎ Corresponding author.

E-mail addresses: linda.frey@pim.uzh.ch (L. Frey), martin.rucklin@naturalis.nl (M. Rücklin), dieter.korn@mfn-berlin.de (D. Korn), chklug@pim.uzh.ch (C. Klug).

30

Chapter I: Alpha Diversity and Palaeoecology

Table

1

Summary

ofpossible

causesandeff

ectsofFamennian(Late

Devonian)andTournaisian(earlyCarboniferous)

bio-events

andenvironmentalperturbations.

Bio-event/environmental

changes

Causes

Effects

Regional:Maïder

Global

Regional:Maïder

Global

Kellwasser

(End-Frasnian)

-Dysaerobic

condition

-Highsealevelstands

( WendtandBelka,1991)

-Anoxia

-Sea-levelch

anges

-Dropin

selenium

level

(e.g.Buggisch

,1991;Sandberg

etal.,2002;Bond

etal.,2004;GerekeandSch

indler,2012;Longetal.,

2015)

-Kellwasserfaciesrich

infossils

(WendtandBelka,1991)

-Loss

inmarinebiodiversity

(e.g.McG

heeJr,2014)

Condroz

(earlyFamennian)

-Regression

(WendtandBelka,1991;

Becker,

1993)

-Regression

(Becker,

1993;Beckeretal.,2012)

-Extinctionoffew

ammonoid

genera

(Becker,

1993)

-Extinctionoffew

ammonoid

genera

(Becker,

1993)

Annulata

(Middle

Famennian)

-Hypoxia

toanoxia,dysoxic

-Transgression

( Hartenfels,2011;Hartenfels

andBecker,

2016a,2016b)

-Anoxia

-Transgression

( Walliser,1996;House,1985;Sandberg

etal.,2002;

Joach

imskietal.,2009;Becker,

1993;Hartenfels,

2011;Rackaetal.,2010)

-Mass

occurrence

oftheammonoid

Platyclymenia

-Small-scale

extinctionin

ammonoids

(Korn,2004;

Hartenfels

andBecker,

2016a,2016b)

-Mass

occurence

oftheammonoid

Platyclymenia

-Small-scale

extinction

(Korn,2004)

Dasberg

(Late

Famennian)

-Hypoxic

conditions

-Twotransgressiveevents

( Hartenfels

andBecker,

2009;

Hartenfels,2011)

-Regionalblackshales

-Transgression

(House,1985;Hartenfels

andBecker,

2009)

-Specieslevelextinction

( Becker,

1993;Hartenfels

andBecker,

2009,Kaiseretal.,2015)

-Coincideswithenvironmentalch

anges

(Hartenfels

andBecker,

2009)

Hangenberg

(End-Famennian)

-Anoxia

-Transgressionfollowedbya

regression

(Kaiseretal.,2011,2015)

-Anoxia

-Globalco

oling

-Regression

-Transgressionfollowedbyaregression

-Eutrophication

-Dropin

selenium

level

(e.g.CaplanandBustin,1999;AlgeoandSch

eckler,

1998;Kaiseretal.,2006;Carm

ichaeletal.,2015)

-Extinctionin

invertebrate

groups(m

ostly

ammonoids,

trilobites,

rhynch

onellid

brach

iopods,

bivalves,

rugose

corals)andin

early

gnathostomes(arthodires,

chondrich

thyans)

( Korn,2004;Kaiseretal.,2011)

-Loss

inmarinebiodiversity

-Bottleneck

invertebrates

(e.g.SallanandCoates,

2010;Friedmanand

Sallan,2012;SallanandGalimberti,2015)

Alum

shale

(Lower-middle

Tournaisian)

-Anoxia

-Transgression

( Kaiseretal.,2011)

-Anoxia

-Transgression

( Becker,1993;Jo

hnsonetal.,1985;Siegmundetal.,

2002)

-Ammonoids:

specieslevelextinction

(Kaiseretal.,2015;seealsoKorn

etal.,2002,2007;Beckeretal.,

2006;EbbighausenandBockwinkel,2007)

-Somegroups(corals,trees,fish)affectedbythe

Hangenberg

Crisis,

diversifiedonly

afterthe

Alum

Shale

Event.

(Poty,1999;Deco

mbeix

etal.,2011;

Denayeretal.,2011;Kaiseretal.,2015)

L. Frey et al.

31

Chapter I: Alpha Diversity and Palaeoecology

because of the abundance (“Kondensat-Lagerstätte”) and exceptional

preservation of fossils (“Konservat-Lagerstätte” sensu Seilacher, 1970).

Among those, Madène El Mrakib (Maïder Basin; cf. Wendt, 1985;

Wendt and Belka, 1991; see Fig. 1, Fig. 3) became famous for its wealth

and diversity of remains of well-preserved invertebrates such as ce-

phalopods (Petter, 1959, 1960; Korn, 1999; Becker, 1995, 2002; Becker

et al., 2000, 2002; Korn and Klug, 2002; Klein and Korn, 2014; Korn

et al., 2014, 2015a, b, 2016a, b; Hartenfels and Becker, 2016a, b; Klug

et al., 2016; Korn and Bockwinkel, 2017), crinoids (Klug et al., 2003;

Webster et al., 2005), brachiopods (Sartenaer, 1998, 1999, 2000) and

trilobites (Struve, 1990). Vertebrate macroremains are rather rare in

most Devonian strata of Morocco, but they become more abundant in

sediments of Late Devonian age. Particularly, three-dimensionally

preserved remains of various Late Devonian (Frasnian and Famennian)

species, mostly of placoderms, from the eastern Anti-Atlas have been

described during the last decades (Lehman, 1956, 1964, 1976, 1977,

1978; Lelièvre and Janvier, 1986, 1988; Lelièvre et al., 1993; Rücklin,

2010, 2011; Rücklin et al., 2015; Rücklin and Clément, 2017). Remains

of other gnathostome groups such as actinopterygians, acanthodians

and chondrichthyans are restricted to microremains, fin spines or iso-

lated jaws (Termier, 1936; Lehman, 1976; Derycke, 1992; Hampe et al.

2004; Derycke et al., 2008; Ginter et al., 2002; Klug et al., 2016;

Derycke, 2017). In several middle Famennian layers of the Maïder

Basin, we recently discovered new, often articulated skeletons of gna-

thostomes such as placoderms, actinopterygians, sarcopterygians and

chondrichthyans, which will strongly improve the knowledge of this

Devonian Konservat-Lagerstätte and thus the palaeoenvironment of this

small marine basin.

In order to better understand Late Devonian ecosystems of the

Maïder through time, we studied alpha diversity and palaeoecology of

the gnathostomes and invertebrates of a series of sufficiently fossili-

ferous strata. Our aim is to answer the following questions: (1) How did

the ecosystem change during the Famennian in the Maïder? (2) Which

groups of gnathostomes were present in the assemblages and were their

occurrences related to invertebrate diversity? (3) What were the effects

of global ecological changes and events on the composition and fluc-

tuations in these assemblages?

2. Material and methods

2.1. Geological setting

Konservat-Lagerstätten conditions prevailed in wide areas of the

Maïder Basin (northeastern Anti-Atlas, Morocco) during the Famennian

(Fig. 1); only south of Tafraoute, exceptionally preserved fossils have

not been found yet. We discovered two layers containing exceptionally

Fig. 1. Geological map of the Maïder and Tafilalt region in the eastern Anti-Altas of Morocco. Localities with phyllocarid layer containing well-preserved remains of gnathostomes are

marked here; faunal changes have been studied from lower to upper Famennian at Madène el Mrakib and from lower to middle Tournaisian at Aguelmous. New data about vertebrate

diversity has been compared to the locality Filon 12 of the Tafilalt region.

L. Frey et al.

32

Chapter I: Alpha Diversity and Palaeoecology

preserved vertebrate fossils, particularly chondrichthyans, in the

Maïder: The middle Famennian (Maeneceras horizon) phyllocarid layer,

named after its high abundance of phyllocarids, contains most of the

gnathostome remains preserved in ferruginous nodules while in the

second layer (early-middle Famennian) fewer remains were found so far

(Fig. 2). A third layer with prevailing Konservat-Lagerstätten conditions

(latest Famennian, Hangenberg Black Shale equivalent) bearing mostly

macroinvertebrates and rarely acanthodian teeth has recently been

documented by Klug et al. (2016).

The phyllocarid layer crops out at various localities such as Bid er

Ras, Jebel Oufatene, Mousgar, Tizi Mousgar, Aguelmous Azizaou, Oued

Chouairef, Tizi n'Aarrat Chouiref and Madène El Mrakib (Fig. 1).

Fig. 2. Positions of the Famennian samples collected from Madène el Mrakib within the global and regional condodont zonations (Ziegler and Sandberg, 1984 and Hartenfels, 2011) and

ammonoid horizons (Becker et al. 2002; Korn et al., 2014). Asterisks and bars mark the approximate position of the samples.

L. Frey et al.

33

Chapter I: Alpha Diversity and Palaeoecology

However, in many of these localities, the sedimentary succession of the

Famennian strata is partially covered by scree, often delivered from the

overlying massive sandstone of the Fezzou Formation which is an

equivalent to the Hangenberg Sandstone of the Tafilalt (Kaiser et al.,

2011; Klug et al., 2016). The Famennian succession is best exposed at

Madène el Mrakib in the southern Maïder because of large scale folding

and erosion towards the Maïder Valley and Tafraoute. Therefore, we

measured a section at this locality from strata of latest Frasnian age

(“Upper Kellwasser Event”) up to the Hangenberg Black Shale equiva-

lent (Rücklin, 2010, 2011; Klug et al., 2016).

Fig. 3. Famennian invertebrate and gnathostome remains from the Maïder. A – B – Bactrites sp., lateral and septal view, ×2, PIMUZ 34012. C – D – Falcitornoceras falciculum, lateral and

ventral views, ×3, PIMUZ 34014. E – F – Ch. (Staffites) afrispina, lateral and ventral views, ×1, PIMUZ 34015. G – H – Planitornoceras pugnax, lateral and ventral views, ×2, PIMUZ

34013. I – J – Platyclymenia annulata, lateral and ventral views, ×1, PIMUZ 34010. K – L – Pseudoclymenia sp., lateral and ventral view, ×1.5, PIMUZ 34011. M – N – Aulatornoceras sp.,

lateral and ventral view, ×1.5, PIMUZ 34016. O – Glyptohallicardia sp., lateral view, ×2, PIMUZ 34017. P – Prosochasma sp., lateral view, ×0.75, PIMUZ 34018. Q – Guerichia sp., lateral

view, ×3, PIMUZ 34019. R – S – Loxopteria sp., lateral views, ×1, PIMUZ 34020. T – U – Paleoneilo sp., lateral and dorsal view, ×2, PIMUZ 34021. V – X – undetermined gastropod,

apical, apertural and basal view, ×2, PIMUZ 34022. Y – Z – undetermined gastropod, apical and apertural view, ×2, PIMUZ 34023. AA – AC – undetermined bellerophontid, lateral,

dorsal and apertural view, ×2, PIMUZ 34024. AD – AH – Phacoiderhynchus antiatlasicus, lateral, dorsal, posterior, ventral and anterior views, ×0.75, PIMUZ 34025. AI – AM –

undetermined brachiopod, lateral, dorsal, posterior, ventral and anterior views, ×1, PIMUZ 34026. AN – Rugose coral, lateral view, ×1.5, PIMUZ 34027. AO – Moroccocrinus ebbigh-

auseni, lateral view, ×1, PIMUZ 34028. AP – Phoebodus sp., labial and aboral view, scale bar= 5mm, PIMUZ A/I 4656. AQ – cladodont shark tooth, lingual view, scale bar= 10mm,

PIMUZ A/I 4657. AR – cladodont shark tooth, labial and oral view, scale bar=5mm, PIMUZ A/I 4658.

L. Frey et al.

34

Chapter I: Alpha Diversity and Palaeoecology

Fig. 4. Changes in diversity and ecospace use during the Famennian at Madène el Mrakib. A – Histograms represent the number of species per association and the changes in diversity

(Table S1). Intervals without histograms often contained rare and/or weathered and compressed fossils which were mostly impossible to determine to the species level. These intervals

were not included in the analysis as they would have resulted in biased species numbers. B – Ecospace expansion (ecological classification after Bush et al., 2007) shows change in the

number of three-dimensional modes of life along the section. C – Changes in gnathostome diversity and composition. Abbreviations of ecological categories: Tiering – p: pelagic, er: erect,

su: surficial, smi: semi-infaunal, si: shallow infaunal; Motility – ff: freely fast, fs: freely slow, fu: facultative unattached, fa: facultative attached, nu: non-motile and unattached, na: non-

motile and attached; Feeding mechanism – sf: suspension feeder, df: deposit feeder, g: grazer, pr: predators.

L. Frey et al.

35

Chapter I: Alpha Diversity and Palaeoecology

2.2. Collection of alpha diversity data

Twelve successive fossil assemblages containing 3591 specimens of

macroinvertebrates (Figs. 3, 4A: associations A-I, K, P-Q; Table S1) co-

occurring with gnathostome remains were collected from the Fa-

mennian of Madène el Mrakib to examine changes in alpha diversity

and palaeoecology. To achieve an adequate resolution in species

abundance and composition and to reduce biases from differences in

sample size, only horizons yielding at least 100 specimens were sam-

pled. Most associations contain numerous formerly pyritized specimens

(now limonitic and haematitic caused by deep weathering of the sedi-

ments) whereas other associations are preserved in limestone nodules,

sideritic nodules and marly beds. In the latter case, specimens were

counted in situ on a bedding plane, depending on the outcrop condi-

tions. To complement our data, we examined 3458 specimens of three

middle Famennian (Platyclymenia and Procymaclymenia horizons) and

two late Famennian (Gonioclymenia to Wocklumeria horizons) samples

from Madène el Mrakib that are housed in the Museum für Naturkunde

in Berlin (Fig. 2: associations J, L-O; Table S1; biozonation is figured in

Korn et al., 2014). This material contains mostly ammonoids and was

published by Korn et al. (2014, 2015a). In addition to the Famennian

samples A to Q from Madène, we examined four samples R to U (Table

S1) containing another 2779 specimens of Early to Middle Tournaisian

(Early Carboniferous) age from Aguelmous. The ammonoids of these

samples were published by Ebbighausen and Bockwinkel (2007).

The ages of the associations were determined by ammonoids (cf.

Korn, 1999; Becker et al., 2002; Korn et al., 2014). For some associa-

tions (A–C, E, G–U in Table S1), a correlation between ammonoid

horizons and conodont zones was possible (Fig. 2; Hartenfels 2011).

The conodont biozonation of the Famennian was recently revised

(Kaiser et al., 2009; Spalletta et al., 2017). However, for the correlation

of our data to global and regional sea level curves (Wendt and Belka,

1991; Haq and Schutter, 2008; Kaiser et al., 2011), we used the pre-

vious conodont zonation of Sandberg et al. (1978) and Ziegler and

Sandberg (1984).

The fossils were determined at species level wherever possible and

subsequently, the relative abundance of every taxon was calculated and

plotted as histograms per association. Moreover, the trophic nucleus

concept of Neyman (1967) was applied to our abundance data to detect

taxa that were dominating each fauna. The trophic nucleus includes

taxa whose relative abundances contribute to 80% of the total abun-

dance of all taxa of a fauna. Additionally to the analysis of the alpha

diversity of complete samples, we counted ammonoid genera of every

association because some middle and upper Famennian samples ex-

clusively contained cephalopods when considering macrofossils only. In

order to compare samples of different sample sizes and to avoid biases

caused by different methods or by varying sampling efforts to each

other, we rarefied the abundance data of each fauna with the software

package PAST (Hammer et al., 2001).

2.3. Ecospace occupation

Analyses in palaeoecology are based on the theoretical ecospace

concept sensu Bush et al. (2007). We grouped all taxa according to

ecological categories of “tiering”, “motility” and “feeding mechanism”.

The combination of these three ecological parameters leads to a unique

three-dimensional mode of life per taxon. ‘Tiering’ categorises the po-

sition of organisms in the water column such as pelagic, erect, surficial,

semi-infaunal and shallow or deep infaunal. We assigned all cephalo-

pods such as ammonoids, bacritids and orthocerids to a pelagic lifestyle.

The habitat of fossil phyllocarid crustaceans is still a matter of debate.

Due to the ferruginous sediments (probably due to pyrite weathering;

the pyrite points at low oxygen conditions) in the Maïder Basin, we

assigned the phyllocarids to a nektobenthic or pelagic mode of life as it

was proposed before by several authors (e.g. Siveter et al., 1991;

Vannier and Abe, 1993; Zatoń et al., 2013). Nevertheless, it has to be

considered that recent benthic phyllocarids are able to survive short-

term anaerobic conditions and that this tolerance might have existed in

extinct taxa as well (Vannier et al., 1997). Besides the crinoid Mor-

occocrinus ebbighauseni that was probably pseudoplanktonic in early to

middle ontogenetic stages and perhaps benthic in adult stages (Klug

et al., 2003; Webster et al., 2005), we found one specimen of a crinoid

holdfast in one of the associations, which might be benthic and erect

(unless it was attached to a living ammonoid). All gastropods (Macro-

chilina), amphigastropods (Bellerophon), brachiopods (rhynchonellids,

Aulacella), rugose corals and trilobites in the samples inhabited the

sediment surface (Bush et al., 2007). Cladochonid-type tabulate corals

(Webster et al., 2005) are lacking in our samples of Madène el Mrakib.

The lifestyle of bivalves is highly diverse and it is still not completely

clarified for all fossil taxa. Species of the genera Guerichia, Prosochasma,

Opisthocoelus, Ptychopteria and Streblopteria were probably living on the

sediment surface (Amler, 1996, 2004, 2006). Amler (2004) assumed

that small bellerophontids, gastropods and the bivalve genus Guerichia

could have lived on erect benthic or floating algal thalli and therefore,

their occurrence was not limited to the sea floor (oxygen-poor condi-

tions cannot be ruled out). We determined these organisms as surficial

because we found only little organic matter in our section and the ha-

bitat might have been too deep for large benthic algae (estimated depth

at Madène el Mrakib is around 200m and therefore below the euphotic

zone; Tessitore et al., 2016). Epibenthic to semi-infaunal lifestyles were

proposed for the bivalve Buchiola (Buchiola) and Glyptohallicardia

(Grimm, 1998) whereas Loxopteria might have been semi-infaunal

(Nagel, 2006). Paleoneilo and Metrocardia as well as lingulid brachio-

pods have been suggested to be shallow infaunal based on actualistic

comparisons (Thayer and Steele-Petrovic, 1975; Amler, 1996; Kříž,

2004). Bivalve species that we could neither determine nor assign to

modes of life, we summarized as ‘benthic organism’ in a separate ca-

tegory.

‘Motility’ refers to locomotory capabilities of organisms such as

freely, fast or slow motile, attached or non-attached facultatively motile

or completely non-motile. We assigned phyllocarids and trilobites to

freely, fast motile organisms (Vannier et al., 1997; Fortey, 2004),

whereas cephalopods and gastropods were rather slow motile organ-

isms (Westermann, 1999; Westermann and Tsujita, 1999). Rugose

corals, crinoids, brachiopods and the bivalve genera Guerichia, Pty-

chopteryia and Streblopteria were non-motile organisms attached to their

substrate whereas Prosochasma and Opisthocoelus were attached as well

but facultatively motile (Bush et al., 2007; Amler, 1996, 2004; Nagel,

2006; Kříž, 2004). Buchiolid bivalves were sessile and unattached

(Grimm, 1998).

‘Feeding mechanism’ describes whether animals acquire food by

predation, mining, grazing suspension filtering or deposit feeding. For

cephalopods, we assume this group to be microphagous predators (Klug

and Lehmann, 2015). Brachiopods, rugose corals, crinoids and most

bivalves were suspension feeders (Paleoneilo represents a deposit feeder;

Amler, 2004) while gastropods were assigned to grazers. The phyllo-

carids of the Maïder were suspension feeders as they were probably

pelagic due to the dysoxic sediments and poor benthic bottom life.

Trilobites had a high variety in acquiring food including feeding on

plankton and organic particles, scavenging or preying on small organ-

isms on or near the bottom (Fortey and Owens, 1999; Fortey, 2004). On

the one hand, the trilobites in our sample were rather small benthic

forms that possibly were deposit feeding. On the other hand, they look

morphologically similar to forms (e.g. big eyes for good vision, Fortey,

2004) that were scavengers or also microphagous predators.

3. Results

3.1. Fluctuations in invertebrate diversity

In total, the 21 associations contain 9828 specimens that were as-

signed to around 227 species (Tables S1, S3). Since we separately

L. Frey et al.

36

Chapter I: Alpha Diversity and Palaeoecology

Fig. 5. Species abundances of 11 successive faunal samples of early to late Famennian age from Madène el Mrakib in the Maïder region (Morocco); red bars represent the dominant

species of each association. A – association A, early Famennian, all three sampled taxa are shown. B – association B, early Famennian, all four sampled taxa are shown here. C – association

C, early Famennian, nine of thirteen taxa are shown. D – association D, middle Famennian, all five sampled taxa are shown here. E – association E, middle Famennian, five of eight taxa

are shown here. F – association F, middle Famennian, eight of eleven taxa are shown here. G – association G, middle Famennian, four of nine taxa are shown here. H – association H,

middle Famennian, seven out of fourteen taxa are shown here. I – association I, middle Famennian, Annulata event layer, all two sampled taxa are shown here. J – association K, middle

Famennian, 11 out of 22 sampled taxa are shown here. K – association Q, late Famennian, Hangenberg Black Shale, five out of eleven sampled taxa are shown here. Not depicted species

are listed in Table S3. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

L. Frey et al.

37

Chapter I: Alpha Diversity and Palaeoecology

analyzed ammonoids and the complete assemblages of selected layers,

the entire assemblage is concerned when we write of species; ammo-

noid diversity is separately depicted and indicated. During the early

Famennian (Cheiloceras horizon), the general species richness increases

from three up to twelve species and one to five ammonoid genera were

counted within this interval (Fig. 4A: association A–C; Fig. 5A–C). The

middle Famennian phyllocarid layer (Maeneceras horizon) contains

numerous gnathostome remains (Fig. 4: association E; Fig. 5E) and

eight species of invertebrates including two ammonoid genera. In the

following middle Famennian associations (Maeneceras to Planitorno-

ceras horizon), 11 to 14 species and one to four ammonoid genera were

present (Fig. 4A, associations F–H; Fig. 5F–H). We found two cepha-

lopod species and one ammonoid genus in the Annulata Black Shales

(middle Famennian, Platyclymenia horizon) whereas in the subsequent

sample, 24 ammonoid species and five ammonoid genera were counted

(Figs. 4I, 7, Table S1: association I-J). In the following sample above the

Annulata Black Shales, species richness reaches 22 species comprising

six ammonoid genera (Fig. 4A: association K; Fig. 5J). In the two other

samples of the middle Famennian (Platyclymenia/Procymaclymenia

horizon), thirteen and nine species were counted and in both samples,

seven ammonoid genera were present (Fig. 7: associations L–M). In the

latest Famennian (Gonioclymenia to Wocklumeria horizons), 13 species

including seven ammonoid genera and three species including one

ammonoid genus were counted (Fig. 7: association N–O). Nine taxa

were found so far in the Wocklumeria horizon (latest Famennian;

however, these layers are not yet sufficiently sampled to provide ac-

curate abundance data (Figs. S1, 4A: association P). In the Hangenberg

Black Shale equivalent (latest Famennian), eleven species containing

four ammonoid genera were found (Fig. 4A, association Q; Fig. 5K). The

earliest Tournaisian association (Fig. 6A) is diverse containing 32 spe-

cies (thereof eight ammonoid genera) while the other three Tournaisian

associations contained eight to fifteen species including two to seven

ammonoid genera (Fig. 6B–D; Table S1, association R–U).

We estimated the sampling bias caused by differences in the method

and duration of sampling by rarefaction analysis. The rarefaction curves

describe the number of taxa that could have been collected with ex-

tending the sampling duration (increasing number of specimens). Some

graphs show steep curves that mean more taxa would have been found

with further collecting within some of the samples (Figs. S2, S3).

However, the biased samples still show low species numbers compared

with the most diverse samples regarding the species numbers that could

have been found within a certain number of collected specimens (we

checked for 90 specimens in each graph). Therefore, trends in diversity

are not strongly biased and here considered reliable; nevertheless, it

cannot be ruled out that these results are influenced by faunal mixing to

a small extend (e.g., Kidwell and Bosence, 1991); indicators for strong

condensation, such as eroded and reworked fossils, very reduced

thickness, extensive hiatuses and iron crusts, are absent.

3.2. Changes in the trophic nucleus

Cephalopods such as ammonoids and orthocerids are the most im-

portant components of the trophic nucleus in some early, middle and

late Famennian samples (Fig. 5B, F, H, J) or were even the only

dominant group (Fig. 5C–D, G, J). Phyllocarids occur only in one

sample but in great abundance and thus are dominant at Madène el

Mrakib (Fig. 5E). Brachiopods and bivalves contributed rarely to the

trophic nucleus except for in a middle Famennian sample and in the

Hangenberg Black Shale equivalent (Fig. 5A, F, H). In the Tournaisian

associations, ammonoids mainly constitute the trophic nucleus except

for one single gastropod species that is present in the oldest Tournaisian

association (association R in Fig. 6A).

3.3. Ecospace occupation during the Famennian

In the early Famennian (Cheiloceras horizon) associations, two to

three modes of life were present and pelagic lifestyles had higher re-

lative abundance than benthic lifestyles (67 versus 33%; Fig. 4B; as-

sociation A–C). The middle Famennian phyllocarid layer (Maeneceras

horizon) contains taxa dominated by pelagic lifestyles and taxa with an

additional mode of life (freely pelagic, fast motile deposit feeders that

are represented by phyllocarids) were found. By contrast, the next

younger association yielded a high relative abundance of benthic modes

of life (82%), which stays high (46–68%) in the following middle Fa-

mennian associations (F–H). The association of the Annulata Black

Shales represents only pelagic modes of life, while the association above

the Annulata Black Shales (Platyclymenia/Procymaclymenia horizon)

contains seven modes of life represented by benthic and pelagic or-

ganisms (freely pelagic, slow-motile predators having the highest

abundance, 57%). In the latest Famennian (Gonioclymenia to Wocklu-

meria horizon), pelagic, freely motile predators were highly abundant

(92%). However, samples were biased towards cephalopods and

therefore, they were excluded from this analysis. The Wocklumeria

horizon (latest Famennian age, association P) contained organisms of

four modes of life and benthic organisms had a high relative abundance

(75%) in comparison to pelagic forms (25%). In the following Hang-

enberg Black Shale equivalent (association Q), only two modes of life

were present of which the pelagic organisms had the highest abundance

(60%). During the Early Tournaisian, the ecospace of associations R and

S (Aguelmous, Fig. 9C) consists of five modes of life but in the following

two associations (Fig. 9C: associations T and U), the ecospace is reduced

to one single mode of life. In all the Tournaisian associations, pelagic

organisms are more abundant than benthos.

In total, we report here 12 or possibly 13 modes of life (some bi-

valves could not be assigned to certain three-dimensional lifestyles)

from 216 theoretically possible combinations. This value lies below the

middle Palaeozoic (Late Ordovician to Devonian) value of about 21

modes of life known from North America and Europe (Bush et al.,

2007). Nineteen modes of life were recorded in the Early Devonian

strata of the Tafilalt region (Jebel Ouaoufilal, Filon 12, see Fig. 1) that

is palaeogeographically and temporally closer situated to the Late De-

vonian of the Maïder (Frey et al., 2014). The slightly impoverished Late

Devonian ecological diversity of the southern half of the Maïder Basin

points at unfavorable living conditions that coincide with the occur-

rence of reddish ferruginous deposits indicating dysoxic environmental

conditions (Korn, 1999; Korn et al., 2015b; Kaiser, 2005; Webster et al.,

2005).

3.4. Diversity and ecospace use in vertebrates

Skeletal remains of chondrichthyans, sarcopterygians and acti-

nopterygians are restricted to specific layers, while placoderms were

found in many more horizons of the section and in other parts of the

eastern Anti-Atlas (Fig. 4C). The highest abundance and species rich-

ness in gnathostomes was found in the phyllocarid layer (middle Fa-

mennian corresponding to the Maeneceras horizon) containing seven

species, whereas only one to two species occurred in the other layers

(Fig. 8). In this layer, we found three species of placoderms (Dunk-

leosteus, Driscollaspis sp. nov., and a second undescribed placoderm n.

gen. et sp.), chondrichthyans (Phoebodus sp., two undescribed clado-

donts) and one actinopterygian (work in progress). Approximately 20m

above the phyllocarid layer, remains of cladodont chondrichthyans

were found, while the sarcopterygians were found six meter below the

Annulata Black Shales (Fig. 4C). Further skeletal remains of Dunkleos-

teus occurred in the late middle Famennian strata and a co-occurrence

of Titanichthys and Dunkleosteus was found in layers of late Famennian

age. The Hangenberg Black Shale equivalent yielded small teeth of

ischnacanthid acanthodians (Klug et al., 2016).

The ecospace use of the gnathostomes of the Maïder Basin is

homogenous. Placoderms such as Dunkleosteus and Titanichthys as well

as cladodont chondrichthyans are assumed to have been pelagic ani-

mals (Ginter et al., 2010; Carr, 2008, Carr and Jackson, 2008; Long &

L. Frey et al.

38

Chapter I: Alpha Diversity and Palaeoecology

Trinajstic, 2010). The two additional placoderm species are assumed to

have lived in the water column as well because they do not show mouth

parts specialized for crushing hard shelled prey. Phoebodont chon-

drichthyans inhabited a narrower range of environments (“moderately

deep to moderately shallow waters”; Ginter et al., 2010). Onychodus

was reported from the inter-reefal basin of the Gogo Formation

(Playford, 1980; Andrews et al., 2006; Long and Trinajstic, 2010) and

therefore, the onychodont sarcopterygians of Madène might have been

living in the water column as well. Most of these gnathostomes have

been assumed to have been preying on other vertebrates or in-

vertebrates such as phyllocarids, cephalopods as well as conodonts

(e.g., Jaekel, 1919; Miles, 1969; Williams, 1990; Mapes et al., 1995,

Zatoń et al., 2017). An exception is the placoderm Titanichthys that was

supposedly a filter feeder because of its long jaw plates with rounded

cross section (Denison, 1978).

4. Discussion

4.1. Invertebrate diversity, ecospace occupation and trophic nuclei during

the Famennian

Examination of alpha diversity, taxonomic composition and eco-

space occupation shows that environmental conditions at Madène el

Mrakib were mostly oxygen-depleted during much of the Famennian.

The faunal composition often includes opportunistic species that were

tolerant to oxygen depletion (Guerichia, buchiolid bivalves, small veti-

gastropods and bellerophontids, Chondrites; Wignall and Simms, 1990;

Amler, 1996, 2004) and deep-water species (e.g. the brachiopods Au-

lacella and Phacoiderhynchus as well as the bivalve Loxopteria;

Sartenaer, 2000; Nagel-Myers et al., 2009). Occurrences of pelagic and

opportunistic taxa as well as fluctuant environments (several trans-

gressions within a larger regressive cycle) in the Famennian were re-

ported from the Maïder Basin (Becker 1993; Hartenfels and Becker,

2009; Hartenfels, 2011; Hartenfels and Becker, 2016a, b) as well as

from localities outside Morocco (Dreesen et al., 1988; Becker and

House, 1997; Sandberg et al., 2002; Kaiser et al., 2006; Marynowski

et al., 2007; Joachimski et al., 2009; Racka et al., 2010).

Fig. 6. Abundances of species and faunal composition of early and middle Tournaisian associations from Aguelmous (Maïder region); data and bed numbers were taken from the

collection of Ebbighausen & Bockwinkel (2007); red bars represent dominant taxa. A – association R, early Tournaisian association, 17 out of 32 sampled taxa are shown here. B –

association S, early Tournaisian association, all eight sampled taxa are shown here. C – association T, early Tournaisian association, all 15 sampled taxa are shown here. D – association U,

middle Tournaisian association, all the nine sampled taxa are shown here. Not depicted species are listed in Table S3. (For interpretation of the references to colour in this figure legend,

the reader is referred to the web version of this article.)

L. Frey et al.

39

Chapter I: Alpha Diversity and Palaeoecology

4.1.1. Early Famennian

In this time interval at Madène el Mrakib, the predominant presence

of brachiopods and the increase in ammonoid diversity can be ex-

plained by a regionally high sea level (Wendt and Belka, 1991) (Fig. 4A:

associations A–C; Fig. 9A–C). Abundant early Famennian rhynchonellid

brachiopods were also reported from the East European Platform and

they were often flourishing during major transgressions (Sokiran,

2002). Similar associations containing abundant cephalopods and bra-

chiopods were reported from the early Fammenian Pa. crepida and

rhomboidea zones of the Holy Cross Mountains (Racki, 1990). During

this time interval, the ecosystem recovered from the Kellwasser Crisis

that caused great structural changes within the marine ecosystem

(Becker, 1986; Droser et al., 2000). However, oxygen-poor conditions

likely persisted from the Frasnian well into the Famennian, as reflected

by the widespread Kellwasser Facies characterized by fossiliferous,

black bituminous early Famennian limestones and claystones in the

Anti-Atlas (Figs. 4, 9; Wendt and Belka, 1991). We did not detect the

Condroz event,which coincides with a regression (sea level curves in

Fig. 9), perhaps due to insufficient sampling. Probably this interval was

covered by scree at Madène el Mrakib (see stratigraphy in Fig. 4).

4.1.2. Middle Famennian

During the middle Famennian, species richness varies between six

and fourteen species (Fig. 4A, associations A–H) in our samples. The

ecospace occupation fluctuates between three and seven modes of life

and the proportion between benthic and pelagic lifestyles is varying

(between 33% and 82%) in these associations. Changes in the compo-

sition of the associations reflect fluctuations in the level of oxygenation

at the seafloor, which, in turn, coincide with global rather than regional

sea level changes (Fig. 9). For instance, the widest extension of eco-

space use (including several benthic lifestyles represented by relatively

large and epibenthic bivalves and the contemporary decrease in am-

monoid diversity; Figs. 4B, 9C, association F) indicates an increased

ventilation of the seafloor that correlates with a global regression

(global sea level curve in Fig. 9; Haq and Schutter, 2008; Becker et al.,

2012). The faunal signals appear to coincide with eustatic rather than

with regional sea-level changes; therefore, we assume that the Fa-

mennian sea level of southern Morocco (Wendt and Belka, 1991) is

more fluctuant than previously reported by these authors (regional sea

level curve in Fig. 9). This is not so surprising when the configuration of

the Maïder Basin is taken into account. Towards the northwest and

southeast, it was surrounded by land and in the West and East by to-

pographic highs, namely the marine Maïder Platform and the Tafilalt

Platform (Wendt, 1985; Kaufmann, 1998). This area of shallower water

limited the water exchange between the two basins; this implies a

further reduction of water exchange during eustatic sea-level low-

stands. By contrast, during lowstands, some areas might have been

more oxygenated because wave action reached closer to the sediment

surface. Another factor we have not assessed yet is the influence of fresh

water from the surrounding land. The existence of rivers is documented

by local occurrences of fine clastic sediments and trunks of Archae-

opteris in the Maïder and Tafilalt Basins (Wendt and Belka, 1991).

4.1.3. Middle Famennian Annulata black shales

During the deposition of the Annulata Black Shales, the ecosystem

was depleted with only two species represented by nektonic cephalo-

pods only at Madène el Mrakib. However, 25 species of cephalopods

(including seven ammonoid genera) were previously reported from the

entire Platyclymenia horizon of the Maïder (Korn, 1999; Korn et al.,

2014, 2015a, b; Fig. 7: association J; Fig. 9A; Table S1). Hartenfels and

Becker (2016a) reported some benthic taxa from the Lower Annulata

Event interval of Mrakib such as small gastropods and guerichid bi-

valves. The dominance of pelagic taxa in our section of Madène el

Mrakib and the possible occurrence of benthos tolerant to oxygen de-

pletion indicates anoxic to dysoxic conditions at the bottom caused by a

global transgression (Haq and Schutter, 2008; Hartenfels, 2011;

Hartenfels and Becker, 2016a). Anoxic conditions during the deposition

of the Annulata Black Shales were reported from geochemical analyses

of southern Poland as well, although they were interrupted by a better

oxygenated phase (Racka et al., 2010). Annulata Black Shales with oc-

currences of pelagic species and the opportunistic bivalve Guerichia

were reported worldwide (Becker, 1993; Becker and House, 1997; Sanz-

López et al., 1999; Becker and House, 2000; Sandberg et al., 2002;

Korn, 1999, 2002, 2004; Becker et al., 2004; Hartenfels et al., 2009;

Hartenfels and Becker, 2016a).

Bio-events do not always strongly affect the ecospace: e.g., the

global species richness in bivalves was affected while the ecological

diversity stayed stable throughout Earth's history (Mondal and Harries,

2016). However, on the regional scale and including higher time-stra-

tigraphic resolution and different invertebrate groups, ecospace might

be more variable. The ecospace use can quickly change as well; for

example, the association that follows the Annulata Black Shales is quite

diverse, thus reflecting a rapid recovery of the biota corresponding to a

global and rapid drop of the sea level (22 species including several

benthic lifestyles and abundant ammonoids are present; Figs. 4A, 9A, C:

Fig. 7. Number of ammonoid genera per association. Associations A–Q were collected

from the Famennian of Madène el Mrakib, associations R–U were sampled from the

Tournaisian of Aguelmous.

L. Frey et al.

40

Chapter I: Alpha Diversity and Palaeoecology

association K). The biota recovered faster than after the Kellwasser

Crisis, probably because the Annulata Event caused less profound eco-

logical changes. Diversity data of the complete invertebrate associa-

tions are missing from the overlying middle Famennian interval.

However, three ammonoid-based samples show that at least in this

group, no major changes were occurring (five to seven genera are

present) and therefore, environmental conditions might have stayed

similar.

In the late Fammenian parts of our section at Madène el Mrakib, we

did not find any black shales corresponding to the Dasberg Crisis at the

transition of the Lower/Middle expansa conodont Zone, although it has

been documented from the Maïder Basin (Becker, 1993; Kaiser et al.,

2008; Hartenfels and Becker, 2009).

4.1.4. Latest Famennian and Hangenberg black shale equivalent

The uppermost Famennian sedimentary succession at Madène el

Mrakib is largely covered by the scree of massive sandstone blocks of

the Fezzou Formation (Hangenberg Sandstone equivalent). In the scree,

we found material of several ammonoid species and only few benthic

organisms. Ammonoid samples (benthos is underrepresented with very

few specimens of nuculid bivalves, rhynchonellid and chonetid bra-

chiopods as well as crinoids) from Madène el Mrakib do not show any

major changes in the Gonioclymenia horizon (seven genera are present

like in the preceding, i.e., slightly older, late Famennian strata; Korn

et al., 2015a; Korn et al., 2016a, b; Table S3). However, only one am-

monoid genus is present in the Kalloclymenia toWocklumeria horizons of

Madène el Mrakib. When comparing collections from other localities in

the Maïder (Lambidia, Tourirt and Bou Tlidat), these comprise seven

ammonoid genera and therefore, some species might have been missed

at Madène el Mrakib due to insufficient sampling effort and the spatial

variation of the fossil record.

The associations of Hangenberg Black Shale equivalent contain a

higher overall diversity including more benthos represented by bivalves

(especially Guerichia elliptica) and bryozoans (but possibly as epizoans

on ammonoids) as well as bioturbation (small and ubiquitous

Chondrites) compared with the Annulata Black Shales (Fig. 4: associa-

tions P–Q; Fig. 9C). The abundance of bioturbation indicates that the

Hangenberg Black Shale equivalent was deposited under hypoxic rather

than entirely anoxic conditions, or at least with varying levels of oxygen

(Klug et al., 2016) at Madène el Mrakib. This finding does not contra-

dict results of geochemical analyses of sections in localities of Morocco

and southern Europe that revealed evidence for anoxia during the de-

position of the Hangenberg Black Shale (Kaiser, 2005, Kaiser et al.,

2006, 2008), because all these benthic organisms (reflected also in the

trace fossils) were likely tolerant towards low oxygen levels at the sea-

floor. Sea-level curves for the Devonian of Morocco show a transgres-

sion during the deposition of the Hangenberg Black Shales followed by

a regression in the overlying Hangenberg Sandstone equivalent (Kaiser,

2005; Kaiser et al., 2011, 2015). Similarly, the global sea level curve

shows a transgression followed by a regression during the Hangenberg

Crisis (Haq and Schutter, 2008).

4.1.5. Early and middle Tournaisian

During the early to middle Tournaisian of Aguelmous, nektonic

cephalopods were flourishing while benthic organisms were rare (bi-

valves, tabulate and rugose corals, gastropods, bellerophontids, bra-

chiopods, spiriferids; Fig. 6, Table S3, association R–U) with some ex-

ceptions in the Maïder and Tafilalt. This is reflected in the scarcity of

strata with abundant bioturbation, but this might be a wrong im-

pression rooting in the fact that the fine-grained siliciclastic sediments

(claystones, siltstones and fine-grained sandstones) are deeply weath-

ered and often covered by scree (personal observation by CK). How-

ever, the samples are biased (sampling) towards ammonoids what is

reflected by the almost parallel curves of the ammonoid genera and

total species richness. Haq and Schutter (2008) reported a sea-level rise

followed by a drop in the sandbergi Zone which could have decreased

the ammonoid diversity at Aguelmous. But the regional sea level (Bou

Tlidat, Kaiser et al., 2011) remained high during this interval and from

several localities of the Tafilalt, a second eustatic transgression was

reported (Lower Alum Shale Event, early/middle Tournaisian

boundary; crenulata biozone), that favored pelagic life (Kaiser et al.,

2008, 2011, 2015). The Lower Alum Shale Event caused extinction in

several groups, however in ammonoids probably only at species level

(Kaiser et al., 2011, 2015; see ammonoid record in Ebbighausen and

Bockwinkel, 2007).

4.2. Diversity and palaeoecology of gnathostomes

Similar to the invertebrates, the Famennian vertebrate diversity of

the Maïder Basin was depleted (placoderms: Dunkleosteus, Titanichthys,

Driscollaspis sp. nov., an undescribed placoderm; chondrichthyans:

Phoebodus sp., two undescribed cladodonts; sarcopterygian:

Onychodontidae; actinopterygian: aff. Moythomasia) (Figs. 4C, 8, 9B).

Previously reported microremains of chondrichthyans from the middle

Famennian (Palmatolepis trachytera and Pa. postera zones) of the Maïder

include similar faunal components (Thrinacodus tranquillus, Stetha-

canthus, possibly Cobelodus, Denaea, undetermined cladodonts) and

pointed at a low diversity as well (Derycke et al., 2008; Derycke et al.,

2014, 2017). The pelagic and highly to moderately mobile predators

(except for the supposedly filter feeding placoderm Titanichthys) pre-

ferably preyed on other pelagic organisms such as cephalopods, fishes

and phyllocarids (Williams, 1990; Mapes et al., 1995) this might ex-

plain the high abundance of gnathostomes (especially chondrichthyans:

23 individuals) in the phyllocarid layer. A co-occurrence of crustaceans

and gnathostomes is known from Frasnian rocks of the Gogo-Formation

of Australia (Briggs et al., 2011) as well as the Cleveland Shale in the

USA (Williams, 1990) and indicates that crustaceans could have been a

nutritive food source for early vertebrates. However, it has to be con-

sidered that the preservational probability was higher in these layers at

these localities as even small phyllocarids have been preserved. The

deposition of the Moroccan phyllocarid layer coincides with a global

regressive cycle showing that the gnathostome preferred an environ-

ment that was shallower and better ventilated. However, when com-

pared to the regional sea-level curve (Fig. 9B), these correlations are not

evident.

Gnathostome abundance and diversity is much lower (one to two

species of placoderms) in the upper parts of the middle and upper

Famennian sedimentary rocks where cephalopods and brachiopods are

most common. Last occurrences of vertebrates, namely two teeth of

ischnacanthid acanthodians, were found in the Hangenberg Black Shale

equivalent of Madène el Mrakib, although the potential for the pre-

servation of vertebrate macroremains is high in these shales (Klug et al.,

2016). Nevertheless, the upper Famennian rocks (Pa. expansa Zone) of

the adjacent Tafilalt region (northeastern Anti-Atlas, Morocco) are rich

in gnathostome microremains (Ginter et al., 2002). Generally, the

middle and upper Famennian carbonates of the Tafilalt region are more

Fig. 8. Species abundance of Famennian gnathostomes in the phyllocarid layer of the

southern Maïder region (northeastern Anti-Atlas, Morocco).

L. Frey et al.

41

Chapter I: Alpha Diversity and Palaeoecology

Fig. 9. Conodont zones (after Ziegler and Sandberg, 1984), ammonoid horizons (after Becker et al., 2002, Korn et al., 2014) and eustatic sea levels of the Famennian and Early

Tournaisian according to Haq and Schutter (2008). Regional sea level is adopted from Wendt and Belka (1991) for the Famennian and from Kaiser et al. (2011) for the Tournaisian.

Arrows mark regional fluctuations proposed by this work here. A – Changes in diversity: invertebrates of Madène el Mrakib and Aguelmous (brown); number of ammonoid genera (blue) B

– Gnathostome diversity of the Maïder (light purple); microremains of the Maïder from Derycke et al. (2008) (dark purple); gnathostomes of the Tafilalt according to Ginter et al. (2002)

and Rücklin and Clément (2017) (orange). Exact positions of vertebrate assemblages within the conodont zones are unknown. C – Changes in pelagic-to-benthic lifestyle ratio within

ecospace at Madène el Mrakib and Aguelmous. Dashed lines: sufficient samples are missing.

L. Frey et al.

42

Chapter I: Alpha Diversity and Palaeoecology

diverse compared to the Maïder Basin in yielding about 17 pelagic and

benthic species of the chondrichthyan genera Jalodus, Thrinacodus,

Phoebodus, Ctenacanthus, Stethacanthus, Symmorium, Cobelodus, Denaea,

Protacrodus, Siamodus, Clairina (Derycke, 1992, 2017; Ginter et al.,

2002). There is a clear difference in preservation of cartilaginous fishes:

more or less complete skeletons in the Maïder versus exclusively mi-

croremains in the Tafilalt. These differences in gnathostome ecology,

diversity and preservation likely resulted from different environmental

conditions between the two regions. The Maïder Basin was deeper than

the Tafilalt pelagic ridge and the western part of the Tafilalt Basin and

was isolated from the open ocean by land and shallow marine areas

(Wendt, 1985, 1995; Wendt et al., 2006; Fröhlich, 2004; Lubeseder

et al., 2010) and therefore, the Maïder Basin and especially its bottom

waters were not well ventilated at all times. These conditions could

explain the poor diversity in invertebrates (especially benthos) and

vertebrates. Additionally, this partially explains the preservation of

articulated vertebrate skeletons as strong currents and scavengers were

rare or absent close to the sediment surface.

In the Tournaisian (Early Carboniferous), neither the Maïder nor the

Tafilalt was rich in vertebrates. This is in accordance with the global

fossil record of vertebrates. With a few exceptions (Alekseev et al.,

1994), early Tournaisian vertebrates are globally rare and even the

extremely diverse late Famennian gnathostome fauna of the Cleveland

Shales vanished entirely (Hansen, 1996; Friedman and Sallan, 2012).

Environmental perturbations during the late Famennian might have

strongly affected the ecosystem but the environment in the Tournaisian

itself was probably not suitable for a diverse gnathostome ecosystem.

Living conditions were probably suitable for some pelagic but not for

benthic gnathostomes due to high sea levels, and an environment

dominated by pelagic cephalopods.

It has to be considered that the biota reacted not only to abiotic but

indirectly also to biotic changes. Biotic factors as causes for changes in

ancient ecosystem are often dismissed because direct evidence of botic

interactions (e.g. stomach contents) are rarely preserved (Williams,

1990; Martill et al., 1994; Cavin, 1996; Richter and Baszio, 2001;

McAllister, 2003; Kriwet et al., 2008; Sallan et al., 2011; Zatoń et al.,

2017; Chevrinais et al., 2017).

In the case of the Famennian and Tournaisian of the Maïder, pre-

vailing anoxic to dysoxic conditions at the seafloor likely limited ben-

thonic life (primary consumers), important food source for small fishes

(secondary consumers), which, in turn, represent prey for bigger fishes

such as predatory placoderms and chondrichthyans (third level con-

sumers). Moreover, the missing predation pressure by gnathostomes on

the ammonoids during the early Tournaisian might have fostered the

rapid re-diversification of ammonoid taxa. Patterns like this were de-

scribed from early Carboniferous crinoids that diversified after the ex-

tinction of their predators (Sallan et al., 2011). However, work on

higher stratigraphic resolution and comparisons among different lo-

calities have to be carried out in order to test the assumed relationship

between extinction of predators and a subsequent radiation of ammo-

noids.

Moreover it is hardly assessable to what extend regional migration

patterns influenced the biota of the Maïder and therefore, if the regional

diversity and ecological trends can be fully assigned to the global

ecosystem.

5. Conclusions

Quantitative analyses of 21 invertebrate associations from the

Famennian to middle Tournaisian sedimentary rocks of the Maïder

Basin document an ecosystem mostly dominated by pelagic in-

vertebrates (particularly cephalopods) and gnathostomes (phoebodont

and cladodont chondrichthyans, placoderm such as Dunkleosteus and

Titanichthys). The ecospace extension of invertebrates reacted to eu-

static and/or regional sea-level changes that caused fluctuations in

ventilation and thus, oxygenation of the seafloor. Based on the variable

occurrence of benthic lifestyles, we propose that changes in regional

sea-level and their effects were stronger than previously thought; this

applies in particular to the beginning of the middle Famennian and

around the Annulata Black Shales. A fluctuating sea level is also sup-

ported by changes in sedimentological composition (alternating clay,

marls and nodular limestone) in the Maïder.

Reduction of ecospace occupation (especially in benthic lifestyles)

occurred after and during bio-events: The slightly recovered biota after

the Kellwasser crises was strongly affected during the late Famennian,

which is reflected in a low ecological diversity (two modes of life)

during the deposition of the Annulata Black Shales. Although the biota

recovered rapidly from this bio-event (seven modes of life), the ecolo-

gical diversity declined again during the Wocklumeria horizon and the

Hangenberg Crisis (five and two modes of life). The biota did not re-

cover very quickly from these crises and ecological depletion persisted

during the early Tournaisian.

Attention should not solely be paid to big events (Kellwasser and

Hangenberg crises) but also to small-scale environmental changes (e.g.

Condroz, Annulata and Dasberg events) as well as other environmental

and ecological changes during the Famennian. Unstable biota fluctu-

ating in numbers of species and modes of life might have been affected

even more strongly by mass-extinctions than biota in stable ecosystems.

It is hardly assessable how the changes in environmental conditions and

invertebrate ecology affected the accompanying vertebrates due to the

comparably low diversity and abundance of gnathostomes in the

Maïder Basin (except for the phyllocarid layer where phyllocarids were

abundant and likely a suitable prey). Nevertheless, biotic interactions

are probable and strong fluctuations in the abundance and diversity of

primary consumers (invertebrates) disturbed the local food web and

represent the likely explanation for the limited abundance and diversity

of secondary and third level consumers (gnathostomes). In order to

obtain more information about the impact of small-scale events and

environmental changes on regional and global biota of the end-

Devonian, it is necessary to examine ecospace occupation of in-

vertebrates as well as vertebrates in other localities during this time

interval.

Acknowledgments

We thank the Swiss National Fond for supporting this project (S-

74602-11-01) and the NWO, VIDI 864.14.009 to support the colla-

boration of Martin Rücklin. The Ministère de l'Energie, des Mines, de

l'Eau et de l'Environnement (Rabat, Morocco) kindly provided permis-

sions for fieldwork and sampling. We thank the excellent preparators

Christina Brühwiler (University of Zurich), Ben Pabst (Zürich) and

Claudine Misérez (Neuchâtel) for their careful work. Many thanks to

René Kindlimann (Aathal), Michael Coates (University of Chicago) and

Michał Ginter for the instructive discussions about Paleozoic and

modern chondrichthyans. We also would like to thank Michael Amler

(Köln) for the kind help with the determination of bivalves. We also

thank the reviewers (Sandra Kaiser, State Museum of Natural History of

Stuttgart; Thomas Becker, University of Münster) who helped to im-

prove this manuscript.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://

doi.org/10.1016/j.palaeo.2017.12.028.

References

Alekseev, A.A., Lebedev, O.A., Barskov, I.S., Barskova, M.I., Kononova, L.I., Chizova, V.A.,

1994. On the stratigraphic position of the Famennian and Tournaisian fossil verte-

brate beds in Andreyevka, Tula Region, Central Russia. Proc. Geol. Assoc. 105,

41–52.

Algeo, T.J., Scheckler, S.E., 1998. Terrestrial-marine teleconnections in the Devonian:

links between the evolution of land plants, weathering processes, and marine anoxic

L. Frey et al.

43

Chapter I: Alpha Diversity and Palaeoecology

events. Philos. Trans. R. Soc. Lond. B 353, 113–130.

Algeo, T.J., Berner, R.A., Maynard, J.B., Scheckler, S.E., 1995. Late Devonian oceanic

anoxic events and biotic crises: ‘rooted’ in the evolution of vascular plants. GSA

Today 5, 63–66.

Algeo, T.J., Scheckler, S.E., Maynard, J.B., 2001. Effects of Middle to Late Devonian

spread of vascular land plants and weathering regimes. In: Gensel, P.G., Edwards, D.

(Eds.), Plants Invade the Land. Columbia University Press, New York, pp. 213–237.

Alroy, J., 2010. Geographical, environmental and intrinsic biotic controls on Phanerozoic

marine diversification. Palaeontology 53, 1211–1235.

Amler, M.R.W., 1996. Die Bivalvenfauna des Oberen Famenniums West-Europas. 2.

Evolution, Paläogeographie, Paläoökologie, Systematik. 2. Palaeotaxodonta und

Anomalodesmata. Geol. Palaeontol. 30, 49–117.

Amler, M.R.W., 2004. Late Famennian bivalve, gastropod and bellerophontid molluscs

from the Refrath 1 Borehole (Bergisch Gladbach-Paffrath Syncline; Ardennes-Rhenish

Massif, Germany). In: Courier Forschungs-Institut Senckenberg. 251. pp. 151–173.

Amler, M.R.W., 2006. Bivalven und Rostroconchien. In: Deutsche Stratigraphische

Kommission (Ed.), Stratigraphie von Deutschland VI. Unterkarbon (Mississippium).

41. Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften, pp. 121–146.

Andrews, S.M., Long, J., Ahlberg, P., Barwick, R., Campbell, K., 2006. The structure of the

sarcopterygian Onychodus jandemarrai n. sp. from Gogo, Western Australia: with a

functional interpretation of the skeleton. Earth Environ. Sci. Trans. R. Soc. Edinb. 96,

197–307.

Becker, R.T., 1986. Ammonoid evolution before, during and after the “Kellwasser-even-

t”—revien and preliminary new results. Global Bio-Events 181–188.

Becker, R.T., 1993. Anoxia, eustatic changes, and Upper Devonian to lowermost

Carboniferous global ammonoid diversity. In: House, M.R. (Ed.), The Ammonoidea:

Environment, Ecology, and Evolutionary Change. Systematic Association Special

Volume 47. pp. 115–164.

Becker, R.T., 1995. Taxonomy and Evolution of Late Famennian Tornocerataceae

(Ammonoidea). Berl. Geowiss. Abh. 16, 607–643.

Becker, R.T., 2002. Alpinites and other Posttornoceratidae (Goniatitida, Famennian). In:

Mitteilungen der Museum für Naturkunde, Geowisse-schaftliche Reihe. 5. pp. 51–73.

Becker, R.T., House, M.R., 1997. Sea-level changes in the Upper Devonian of the Canning

Basin, Western Australia. Cour. Forschungsinst. Senck. 199, 129–146.

Becker, R.T., House, M.R., 2000. Devonian ammonoid zones and their correlation with

established series and stage boundaries. Cour. Forschungsinst. Senck. 220, 113–151.

Becker, R.T., Bockwinkel, J., Ebbighausen, V., House, M.R., 2000. Jebel Mrakib, Anti-

Atlas (Morocco), a potential Upper Famennian substage boundary stratotype section.

In: Notes et Mémoires du Service géologique Maroc. 399. pp. 75–86.

Becker, R.T., House, M.R., Bockwinkel, J., Ebbighausen, V., Aboussalam, Z.S., 2002.

Famennian ammonoid zones of the eastern anti-atlas (southern Morocco). In:

Münstersche Forschungen zur Geologie und Paläontologie. 93. pp. 159–205.

Becker, R.T., Ashouri, A.R., Yazdi, M., 2004. The upper Devonian Annulata event in the

Shotori range (eastern Iran). Neues Jahrb. Geol. Palaontol. Abh. 119–143.

Becker, R.T., Kaiser, S.I., Aboussalam, Z.S., 2006. The Lower Alum Shale Event (Middle

Tournaisian) in Morocco – facies and faunal changes. In: Aretz, M., Herbig, H.-G

(Eds.), Carboniferous Conference Cologne, From Platform to Basin. Kölner Forum für

Geologie und Paläontologie, Program and Abstracts. 15. pp. 7–8.

Becker, R.T., Gradstein, F.M., Hammer, O., 2012. The Devonian period. In: Gradstein,

F.M., Ogg, J.G., Schmitz, M.D., Ogg, G.M. (Eds.), The Geologic Time Scale. Elsevier,

pp. 559–603.

Becker, R.T., Kaiser, S.I., Aretz, M., 2016. Review of chrono-, litho- and biostratigraphy

across the global Hangenberg crisis and Devonian–carboniferous boundary. Geol.

Soc. Lond., Spec. Publ. 423 (1), 355–386.

Bond, D.P.G., Wignall, P.B., 2008. The role of sea-level change and marine anoxia in the

Frasnian-Famennian (Late Devonian) mass extinction. Palaeogeogr. Palaeoclimatol.

Palaeoecol. 263, 107–118.

Bond, D., Wignall, P.B., Racki, G., 2004. Extent and duration of marine anoxia during the

Frasnian–Famennian (Late Devonian) mass extinction in Poland, Germany, Austria

and France. Geol. Mag. 141 (2), 173–193.

Briggs, D.E.G., Rolfe, W.D.I., Butler, P.D., Liston, J., Ingham, J.K., 2011. Phyllocarid

crustaceans from the upper Devonian Gogo formation, Western Australia. J. Syst.

Palaeontol. 9 (3), 399–424.

Buggisch, W., 1991. The global Frasnian-Famennian “Kellwasser event”. Geol. Rundsch.

80 (1), 49–72.

Bush, A.M., Bambach, R.K., Daley, G.M., 2007. Changes in theoretical ecospace utilization

in marine fossil assemblages between the mid-Paleozoic and late Cenozoic.

Paleobiology 33 (1), 76–97.

Caplan, M.L., Bustin, R.M., 1999. Devonian-carboniferous Hangenberg mass extinction

event, widespread organic-rich mudrock and anoxia: causes and consequences.

Palaeogeogr. Palaeoclimatol. Palaeoecol. 148, 187–207.

Carmichael, S.K., Waters, J.A., Batchelor, C.J., Coleman, D.M., Suttner, T.J., Kido, E.,

McCain Moore, L., Chadimová, L., 2015. Climate instability and tipping points in the

Late Devonian: detection of the Hangenberg event in an open oceanic island arc in

the Central Asian Orogenic Belt. Gondwana Res. 32, 213–231.

Carr, R.K., 2008. Paleoecology of Dunkleosteus terrelli (Placodermi: Arthrodira). In:

Kirtlandia. 57. pp. 36–45.

Carr, R.K., Jackson, G.L., 2008. The vertebrate fauna of the Cleveland member

(Famennian) of the Ohio Shale. In: Guide to the Geology and Paleontology of the

Cleveland Member of the Ohio Shale. 68th Annual Meeting of the Society of

Vertebrate Paleontology, Cleveland, Ohio.

Cavin, L., 1996. Supposed and direct evidence of trophic relationships within the marine

fish community from the Lower Turonian of Goulmima, Morocco. In: First European

Workshop on Vertebrate Palaeontology. Online Series 1 Geological Society of

Denmark.

Chevrinais, M., Jacquet, C., Cloutier, R., 2017. Early establishment of vertebrate trophic

interactions: food web structure in middle to late Devonian fish assemblages with

exceptional fossilization. Bull. Geosci. 92 (4), 491–510.

Decombeix, A.L., Meyer-Berthaud, B., Galtier, J., 2011. Transitional changes in arbor-

escent lignophytes at the Devonian-carboniferous boundary. J. Geol. Soc. Lond. 168,

547–557.

Denayer, J., Poty, E., Aretz, M., 2011. Uppermost Devonian and Dinantian rugose corals

from Southern Belgium and surrounding areas. Kölner Forum für Geologie und

Paläontologie 20, 151–201.

Denison, R., 1978. Handbook of Paleoichthyology. Placodermi, vol. 2 Gustav Fischer,

Stuttgart.

Derycke, C., 1992. Microrestes de Sélaciens et autres Vertébrés du Dévonien supérieur du

Maroc. Bulletin du Muséum national d'Histoire Naturelle, Section C, Sciences de la

terre, paléontologie, géologie, minéralogie 14 (1), 15–61.

Derycke, C., 2017. Paléobiodiversité des gnathostomes (chondrichthyens, acanthodiens et

actinoptérygiens) du Dévonien du Maroc (NW Gondwana). In: Zouhri, S. (Ed.),

Paléontologie des vertébrés du Maroc: état des connaissance, Mémoires de la Société

Géologique de France 180, pp. 624.

Derycke, C., Spalletta, C., Perri, M.C., Corradini, C., 2008. Famennian chondrichthyan

microremains from Morocco and Sardinia. J. Paleontol. 82 (5), 984–995.

Derycke, C., Olive, S., Groessens, E., Goujet, D., 2014. Paleogeographical and paleoeco-

logical constraints on Paleozoic vertebrates (chondrichthyans and placoderms) in the

Ardenne Massif Shark radiations in the Famennian on both sides of the Palaeotethys.

Palaeogeogr. Palaeoclimatol. Palaeoecol. 414, 61–67.

Dreesen, R., Paproth, E., Thorez, J., 1988. Events documented in Famennian sediments

(Ardenne-Rhenish Massif, Late Devonian, NW Europe). In: Devonian of the World:

Proceedings of the 2nd International Symposium on the Devonian System — Memoir

14. Sedimentation, vol. II. pp. 295–308.

Droser, M.L., Bottjer, D.J., Sheehan, P.M., McGhee Jr., G.R., 2000. Decoupling of taxo-

nomic and ecologic severity of Phanerozoic marine mass extinctions. Geology 28 (8),

675–678.

Ebbighausen, V., Bockwinkel, J., 2007. Tournaisian (Early Carboniferous/Mississippian)

ammonoids from the Ma'der Basin (Anti-Atlas, Morocco). Fossil Record 10 (2),

125–163.

Fortey, R.A., 2004. The lifestyles of the trilobites. Am. Sci. 92, 446–453.

Fortey, R.A., Owens, R.M., 1999. Feeding habits in trilobites. Palaeontology 42 (3),

429–465.

Frey, L., Naglik, C., Hofmann, R., Schemm-Gregory, M., Frýda, J., Kröger, B., Taylor, P.D.,

Wilson, M.A., Klug, C., 2014. Diversity and palaeoecology of early Devonian in-

vertebrate associations in the Tafilalt (Anti-Atlas, Morocco). Bull. Geosci. 89 (1),

75–112.

Friedman, M., Sallan, L.C., 2012. Five hundred million years of extinction and recovery: a

Phanerozoic survey of large-scale diversity patterns in fishes. Palaeontology 55 (4),

707–742.

Fröhlich, S., 2004. Evolution of a Devonian carbonate shelf at the northern margin of

Gondwana (Jebel Rheris,eastern Anti-Atlas, Morocco) (Unpublished PhD Thesis).

University of Tübingen, Germany.

Gereke, M., Schindler, E., 2012. “Time-specific facies” and biological crisis — the

Kellwasser event interval near the Frasnian/Famennian boundary (Late Devonian).

Palaeogeogr. Palaeoclimatol. Palaeoecol. 367–368, 19–29.

Ginter, M., Hairapetian, V., Klug, C., 2002. Famennian chondrichthyans from the shelves

of North Gondwana. Acta Geol. Pol. 52 (2), 169–215.

Ginter, M., Hampe, O., Duffin, C.J., 2010. Chondrichthyes: Paleozoic Elasmobranchii:

teeth. In: Schultze, H. (Ed.), Handbook of Paleoichthyology. vol. 3D 168 p.

Goddéris, Y., Joachimski, M.M., 2004. Global change in the Late Devonian: modelling the

Frasnian-Famennian short-term carbon isotope excursions. Palaeogeogr.

Palaeoclimatol. Palaeoecol. 202, 309–329.

Grimm, M.G., 1998. Systematik und Paläoökologie der Buchiolinae nov. subfam.

Schweizerische Paläontologische Abhandlungen 118, 1–176.

Hammer, Ø., Harper, D.A.T., Ryan, P.D., 2001. PAST: Palaeontological statistics software

package for education and data analysis. Palaeontol. Electron. 4 (1), 1–9.

Hampe, O., Aboussalam, Z.S., Becker, R.T., 2004. Omalodus teeth (Elasmobranchii:

Omalodontida) from the northern Gondwana margin (middle Givetian: ansatus con-

odont Zone, Morocco). In: Arratia, G., Wilson, M.V.H., Cloutier, R. (Eds.), Recent

Advances in the Origin and Early Radiation of Vertebrates, pp. 487–504.

Hansen, M.C., 1996. Phylum Chordata–vertebrate fossils. In: Feldman, R.M. (Ed.), Fossils

of Ohio. Bulletin 70. Division of Geological Survey, Columbus 288–369 pp.

Haq, B.U., Schutter, S.R., 2008. A chronology of Paleozoic sealevel changes. Science 322,

64–68.

Hartenfels, S., 2011. Die globalen Annulata-Events und die Dasberg-Krise (Famennium,

Oberdevon) in Europa und Nord-Afrika – hochauflösende Conodonten-Stratigraphie,

Karbonat-Mikrofazies, Paläoökologie und Paläodiversität. Münstersche Forschungen

zur Geologie und Paläontologie 105, 1–527.

Hartenfels, S., Becker, R.T., 2009. Timing of the global Dasberg crisis–implications for

Famennian eustasy and chronostratigraphy. Palaeontogr. Am. 63, 71–97.

Hartenfels, S., Becker, R.T., 2016a. The global annulata events: review and new data from

the Rheris Basin (northern Tafilalt) of SE Morocco. In: Becker, R.T., Königshof, P.,

Brett, C.E. (Eds.), Devonian Climate, Sea Level and Evolutionary Events. 423

Geological Society, London, Special Publications. http://dx.doi.org/10.1144/

SP423.14.

Hartenfels, S., Becker, R.T., 2016b. Age and correlation of the transgressive

Gonioclymenia limestone (Famennian, Tafilalt, eastern Anti-Atlas, Morocco). Geol.

Mag. 1–44.

Hartenfels, S., Becker, R.T., Tragelehn, H., 2009. Marker conodonts around the global

Annulata Events and the definition of an Upper Famennian substage. In:

Subcommission on Devonian Stratigraphy Newsletter. 24. pp. 40–45.

House, M.R., 1985. Correlation of mid-Palaeozoic ammonoid evolutionary events with

L. Frey et al.

44

Chapter I: Alpha Diversity and Palaeoecology

global sedimentary perturbations. Nature 313, 17–22.

House, M.R., 2002. Strength, timing, setting and cause of mid-Palaeozoic extinctions.

Palaeogeogr. Palaeoclimatol. Palaeoecol. 181, 5–25.

Jaekel, O., 1919. Die Mundbildung der Placodermen. In: Sitzungsberichte der Gesellschaft

Naturforschender Freunde, Berlin. 1919. pp. 73–110.

Joachimski, M.M., Buggisch, W., 2002. Conodont apatite δ18O signatures indicate cli-

matic cooling as a trigger of the late Devonian mass extinction. Geology 30 (8),

711–714.

Joachimski, M.M., Breisig, S., Buggisch, W., Talent, J.A., Mawson, R., Gereke, M.,

Morrow, J.R., Day, J., Weddige, K., 2009. Devonian climate and reef evolution: in-

sights from oxygen isotopes in apatite. Earth Planet. Sci. Lett. 284, 599–609.

Johnson, J.G., Klapper, G., Sandberg, C.A., 1985. Devonian eustatic fluctuations in

Euramerica. Geol. Soc. Am. Bull. 96, 567–587.

Kaiser, S.I., 2005. Mass Extinctions, Climatic and Oceanographic Changes at the

Devonian/Carboniferous boundary (Unpublished Dissertation). University of

Bochum, pp. 1–156.

Kaiser, S.I., Steuber, T., Becker, R.T., Joachimski, M.M., 2006. Geochemical evidence for

major environmental change at the Devonian–carboniferous boundary in the carnic

alps and the Rhenish massif. Palaeogeogr. Palaeoclimatol. Palaeoecol. 240 (1),

146–160.

Kaiser, S.I., Steuber, T., Becker, T., 2008. Environmental change during the late

Famennian and early Tournaisian (late Devonian-early carboniferous): implications

from stable isotopes and conodont biofacies in southern Europe. Geol. J. 42,

241–260.

Kaiser, S.I., Becker, R.T., Spalletta, C., Steuber, T., 2009. High-resolution conodont stra-

tigraphy, biofacies, and extinctions around the Hangenberg event in pelagic succes-

sions from Austria, Italy, and France. Palaeontogr. Am. 63, 97–139.

Kaiser, S.I., Becker, R.T., Steuber, T., Aboussalam, S.Z., 2011. Climate-controlled mass

extinctions, facies, and sea-level changes around the Devonian-Carboniferous

boundary in the eastern Anti-Atlas (SE Morocco). Palaeogeogr. Palaeoclimatol.

Palaeoecol. 310, 340–364.

Kaiser, S.I., Aretz, M., Becker, R.T., 2015. The global Hangenberg crisis

(Devonian–Carboniferous transition): review of a first-order mass extinction. In:

Becker, R.T., Königshof, P., Brett, C.E. (Eds.), Devonian Climate, Sea Level and

Evolutionary Events. Geological Society of London, Special Publications, pp.

387–437.

Kaufmann, B., 1998. Facies, stratigraphy and diagenesis of middle Devonian reef- and

mud-mounds in the Mader (eastern Anti-Atlas, Morocco). Acta Geol. Pol. 48, 43–106.

Kidwell, S.M., Bosence, D.W.J., 1991. Taphonomy and time-averaging of marine shelly

faunas. In: Allison, P.A., Briggs, D.E.G. (Eds.), Releasing the Data Locked in the Fossil

Record. Topics in Geobiology 9. Plenum Press, New York, pp. 113–211.

Klein, C., Korn, D., 2014. A morphometric approach to conch ontogeny of Cymaclymenia

and related genera (Ammonoidea, late Devonian). Fossil Record 17 (1), 1–32.

Klug, C., Lehmann, J., 2015. Soft part anatomy of ammonoids: reconstructing the animal

based on exceptionally preserved specimens and actualistic comparisons. In: Klug, C.,

Korn, D., de Baets, K., Kruta, I., Mapes, R.H. (Eds.), Ammonoid Paleobiology, Volume

I: from Anatomy to Ecology. Topics in Geobiology 43. Springer, Dordrecht, pp.

539–552.

Klug, C., Rücklin, M., Meyer-Berthaud, B., Soria, A., 2003. Late Devonian pseudoplank-

tonic crinoids from Morocco. Neues Jahrbuch für Geologie und Mineralogie 3,

153–163.

Klug, C., Kröger, B., Rücklin, M., Korn, D., Schemm-Gregory, M., De Baets, K., Mapes,

R.H., 2008. Ecological change during the early Emsian (Devonian) in the Tafilalt

(Morocco), the origin of the Ammonoidea, and the first African pyrgocystid

edrioasteroids, machaerids and phyllocarids. Palaeontographica A 283, 1–94.

Klug, C., Frey, L., Korn, D., Jattiot, R., Rücklin, M., 2016. The oldest Gondwanan ce-

phalopod mandibles (Hangenberg black shale, late Devonian) and the mid-palaeozoic

rise of jaws. Palaeontology 19, 611–629.

Korn, D., 1999. Famennian Ammonoid Stratigraphy of the Ma'der and Tafilalt (Eastern

Anti-Atlas, Morocco). Abhandlungen der geologischen Bundesanstalt 54, 147–179.

Korn, D., 2002. Die Ammonoideen-Fauna der Platyclymenia annulata-Zone vom

Kattensiepen (Oberdevon, Rheinisches Schiefergebirge). Senckenb. Lethaea 82 (2),

557–608.

Korn, D., 2004. The mid-Famennian ammonoid succession in the Rhenish Mountains: the

“annulata Event” reconsidered. Geological Quarterly 48, 245–252.

Korn, D., Bockwinkel, J., 2017. The genus Gonioclymenia (Ammonoidea; late Devonian) in

the anti-atlas of Morocco. Neues Jahrb. Geol. Palaontol. Abh. 285 (1), 97–115.

Korn, D., Klug, C., 2002. Fossilium Catalogus I: Animalia Pars 138, Ammoneae Devonicae.

Backhuys Publishers, Leiden, Netherlands.

Korn, D., Klug, C., Ebbighausen, V., Bockwinkel, J., 2002. Palaeogeographical meaning of

a Middle Tournaisian ammonoid fauna from Morocco. Geol. Palaeontol. 36, 79–86.

Korn, D., Bockwinkel, J., Ebbighausen, V., 2014. Middle Famennian (Late Devonian)

ammonoids from the Anti-Atlas of Morocco, 1. Prionoceras. Neues Jahrb. Geol.

Palaontol. Abh. 272 (2), 167–204.

Korn, D., Bockwinkel, J., Ebbighausen, V., 2015a. The late Devonian ammonoid

Mimimitoceras in the Anti-Atlas of Morocco. Neues Jahrb. Geol. Palaontol. Abh. 275

(2), 125–150.

Korn, D., Bockwinkel, J., Ebbighausen, V., 2015b. Middle Famennian (late Devonian)

ammonoids from the Anti-Atlas of Morocco, 2. Sporadoceratidae. Neues Jahrb. Geol.

Palaontol. Abh. 278 (1), 47–77.

Korn, D., Bockwinkel, J., Ebbighausen, V., 2016a. The late Famennian tornoceratid am-

monoids in the Anti-Atlas of Morocco. Neues Jahrb. Geol. Palaontol. Abh. 281 (2),

201–220.

Korn, D., Bockwinkel, J., Ebbighausen, V., 2016b. Middle Famennian (late Devonian)

ammonoids from the Anti-Atlas of Morocco. 3. Tornoceratids. Neues Jahrb. Geol.

Palaontol. Abh. 281 (3), 267–281.

Kriwet, J., Witzmann, F., Klug, S., Heidtke, U.H., 2008. First direct evidence of a verte-

brate three-level trophic chain in the fossil record. Proc. R. Soc. Lond. B Biol. Sci. 275

(1631), 181–186.

Kříž, J., 2004. Latest Frasnian and earliest Famennian (Late Devonian) bivalves from the

Montagne Noire (France). In: Senckenbergiana lethaea. 84. pp. 85–123.

Lehman, J.P., 1956. Les Arthrodires du Dévonien supérieur du Tafilalt (Sud Marocain). In:

Notes et Mémoires du Service Géologique du Maroc. 129. pp. 1–70.

Lehman, J.P., 1964. A propos de quelques Arthrodires et Ichthyodorulites sahariens.

Mémoire IFAN 68, 193–200.

Lehman, J.P., 1976. Nouveaux poissons fossiles du Dévonien du Maroc. In: Annales de

Paléontologie Vertébrés. 62. pp. 1–34.

Lehman, J.P., 1977. Sur la présence d'un Ostéolépiforme dans le Dévonien supérieur du

Tafilalt. In: Compte-Rendus de l'Académie des Sciences. 285D. pp. 151–153.

Lehman, J.P., 1978. A propos de deux poissons du Famennien du Tafilalt. In: Annales de

Paléontologie Vertébrés. 64. pp. 143–152.

Lelièvre, H., Janvier, P., 1986. L'Eusthénopteridé (Osteichthyes, Sarcopterygii) du

Famennian (Dévonien supérieur) du Tafilalt (Maroc): nouvelle description. In:

Bulletin du Muséum National d'Histoire naturelle, 4e Série, Section C, Sciences de la

Terre, Paléontologie, Géologie, Minéralogie. 3. pp. 351–365.

Lelièvre, H., Janvier, P., 1988. Un Actinistien (Sarcopterygii, Vertebrata) dans le Dévonien

supérieur du Maroc. In: Compte-Rendus de l'Académie des Sciences, Paris. 307. pp.

1425–1430.

Lelièvre, H., Janvier, P., Blieck, A., 1993. Silurian-Devonian vertebrate biostratigraphy of

western Gondwana and related terranes (South America, Africa, Armorica-Bohemia,

Middle East). In: Palaeozoic Vertebrate Biostratigraphy and Biogeography, pp.

139–173.

Long, J.A., Trinajstic, K., 2010. The late Devonian Gogo formation Lägerstatte of Western

Australia: exceptional early vertebrate preservation and diversity. Annu. Rev. Earth

Planet. Sci. 38, 255–279.

Long, J.A., Large, R.R., Lee, M.S., Benton, M.J., Danyushevsky, L.V., Chiappe, L.M.,

Halpin, J.A., Cantrill, D., Lottermoser, B., 2015. Severe selenium depletion in the

Phanerozoic oceans as a factor in three global mass extinction events. Gondwana Res.

36, 209–218.

Lubeseder, S., Rath, J., Rücklin, M., Messbacher, R., 2010. Controls on Devonian hemi-

pelagic limestone deposition analyzed on cephalopod ridge to slope sections, Eastern

Anti-Atlas, Morocco. Facies 56, 295–315.

Mapes, R.H., Sims, M.S., Boardman, D.R., 1995. Predation on the Pennsylvanian am-

monoid Gonioloboceras and its implications for allochthonous vs. autochthonous ac-

cumulations of Goniatites and other ammonoids. J. Paleontol. 69 (3), 441–446.

Martill, D.M., Taylor, M.A., Duff, K.L., Riding, J.B., Bown, P.R., 1994. The trophic

structure of the biota of the Peterborough member, Oxford clay formation (Jurassic),

UK. J. Geol. Soc. Lond. 151, 173–194.

Marynowski, L., Rakociński, M., Zatoń, M., 2007. Middle Famennian (late Devonian)

interval with pyritized fauna from the Holy Cross Mountains (Poland): organic geo-

chemistry and pyrite framboid diameter study. Geochem. J. 41, 187–200.

McAllister, J., 2003. Predation of Fishes in the Fossil Record. In: Kelley, P.H., Kowalewski,

M., Hansen, T.H. (Eds.), Predator–Prey Interactions in the Fossil Record. Academic/

Plenum Publishers, New York, NY, pp. 303–324.

McGhee, G.R., 1988. The late Devonian extinction event: evidence for abrupt ecosystem

collapse. Paleobiology 14 (3), 250–257.

McGhee, G.R., 1996. The Late Devonian Mass Extinction: The Frasian/Famennian Crises.

Columbia University Press, New York (303 p).

McGhee Jr., G.R., 2001. The `multiple impacts hypothesis` for mass extinction: a com-

parison of the late Devonian and the late Eocene. Palaeogeogr. Palaeoclimatol.

Palaeoecol. 176, 47–58.

McGhee Jr., G.R., 2014. When the Invasion of Land Failed: The Legacy of the Devonian

Extinctions. Columbia University Press, New York 317 pp.

McGhee Jr., G.R., Clapham, M.E., Sheehan, P.M., Bottjer, D.J., Droser, M.L., 2013. A new

ecological severity ranking of major Phanerozoic biodiversity crises. Palaeogeogr.

Palaeoclimatol. Palaeoecol. 370, 260–270.

Miles, R.S., 1969. Features of placoderm diversification and the evolution of the ar-

throdire feeding mechanism. In: Transactions of the Royal Society of Edinburgh. 68.

pp. 123–170.

Mondal, S., Harries, P.J., 2016. Phanerozoic trends in ecospace utilization: the bivalve

perspective. Earth Sci. Rev. 152, 106–118.

Murphy, A.E., Sageman, B.B., Hollander, D.J., 2000. Eutrophication by decoupling of the

marine biogeochemical cycles of C, N, and P: a mechanism for the late Devonian mass

extinction. Geology 28 (5), 427–430.

Nagel, J., 2006. Middle and Upper Devonian Cryptodonta (Bivalvia) from the Pelagic

Hercynian Facies - Taxonomy, Stratigraphy, and Paleoecology (Unpublished PhD-

thesis). Westfälischen Wilhelms-Universität, Münster.

Nagel-Myers, J., Amler, M.R.W., Becker, R.T., 2009. The Loxopteriinae n. subfam.

(Dualinidae, Bivalvia): review of a common bivalve taxon from the Late Devonian

pelagic facies. Palaeontogr. Am. 63, 167–185.

Newell, N.D., 1952. Periodicity in invertebrate evolution. J. Paleontol. 371–385.

Newell, N.D., 1956. Catastrophism and the fossil record. Evolution 10 (1), 97–101.

Newell, N.D., 1963. Crises in the history of life. Sci. Am. 208, 77–93.

Neyman, A.A., 1967. Limits to the application of the ‘trophic group’ concept in benthic

studies. In: Oceanology, Academy of Sciences of the USSR. 7. pp. 49–155.

Petter, G., 1959. Goniatites devoniénnes du Sahara. In: Publications du Sérvice de la Carte

Géologique de l'Algérie, nouvelle série, Paléontologie 2. pp. 1–313.

Petter, G., 1960. Clymènies du Sahara. In: Publications du Sérvice de la Carte Géologique

de l'Algérie, nouvelle série, Paléontologie 6. pp. 1–58.

Playford, P.E., 1980. The Devonian “great barrier reef” of the Canning Basin, Western

Australia. Am. Assoc. Pet. Geol. 64, 814–840.

Poty, E., 1999. Famennian and Tournaisian recoveries of shallow water Rugosa following

L. Frey et al.

45

Chapter I: Alpha Diversity and Palaeoecology

late Frasnian andblate Strunian major crisis, southern Belgium and surrounding area,

Hunan (South China) and the Omolon region (NE Siberia). Palaeogeogr.

Palaeoclimatol. Palaeoecol. 154, 11–26.

Racka, M., Marynowski, L., Filipiak, P., Sobstel, M., Pisarzowska, A., Bond, D.P.G., 2010.

Anoxic Annulata events in the late Famennian of the Holy Cross Mountains (southern

Poland): geochemical and palaeontological record. Palaeogeogr. Palaeoclimatol.

Palaeoecol. 297, 549–575.

Racki, G., 1990. Frasnian/Famennian event in the Holy Cross Mts, Central Poland: stra-

tigraphic and ecologic aspects. In: Kauffman, E.G., Walliser, A. (Eds.), Extinction

Events in Earth History. Lecture Notes in Earth Sciences. 30. pp. 169–181.

Racki, G., 2005. Toward understanding Late Devonian global events: few answers, many

questions. In: Over, D.J., Morrow, J.R., Wignall, P.B. (Eds.), Understanding Late

Devonian and Permian-Triassic Biotic and Climatic Events: Towards an Integrated

Approach. Elsevier, Amsterdam, pp. 337.

Raup, D.M., Sepkoski, J.J., 1982. Mass extinctions in the marine fossil record. Science

215, 1501–1503.

Richter, G., Baszio, S., 2001. Traces of a limnic foodweb in the Eocene Lake Messel—a

preliminary report based on fish coprolite analyses. Palaeogeogr. Palaeoclimatol.

Palaeoecol. 166, 345–368.

Riquier, L., Tribovillard, N., Averbuch, O., Devleeschouwer, X., Riboulleau, A., 2006. The

late Frasnian Kellwasser horizons of the Harz Mountains (Germany): two oxygen-

deficient periods resulting from different mechanisms. Chem. Geol. 233 (1), 137–155.

Rücklin, M., 2010. A new Frasnian placoderm assemblage from the eastern anti-atlas,

Morocco, and its palaeobiogeographical implications. Palaeoworld 19, 87–93.

Rücklin, M., 2011. First selenosteid placoderms from the eastern Anti-Atlas of Morocco;

osteology, phylogeny and palaeogeographical implications. Palaeontology 54, 25–62.

Rücklin, M., Clément, G., 2017. Une revue des Placodermes et Sarcoptérygiens du

Dévonien du Maroc. In: Zouhri, S. (Ed.), Paléontologie des vertébrés du Maroc: état

des connaissance, Mémoires de la Société Géologique de France. 180. pp. 624.

Rücklin, M., Long, J.A., Trinajstic, K., 2015. A new selenosteid arthrodire (‘Placodermi’)

from the Late Devonian of Morocco. J. Vertebr. Paleontol. 35 (2), 1–13 e908896.

Sallan, L.C., Coates, M.I., 2010. End Devonian extinction and a bottleneck in the early

evolution of modern jawed vertebrates. Proc. Natl. Acad. Sci. 107 (22),

10131–10135.

Sallan, L.C., Galimberti, A.K., 2015. Body-size reduction in vertebrates following the end-

Devonian mass extinction. Science 350 (6262), 812–815.

Sallan, L.C., Kammer, T.W., Ausich, W.I., Cook, L.A., 2011. Persistent predator–prey

dynamics revealed by mass extinction. Proc. Natl. Acad. Sci. 108 (20), 8335–8338.

Sandberg, C.A., Ziegler, W., Leuteritz, K., Brill, S.M., 1978. Phylogeny, speciation, and

zonation of Siphonodella (Conodonta, upper Devonian and lower carboniferous).

Newsl. Stratigr. 7 (2), 102–120.

Sandberg, C.A., Morrow, J.R., Ziegler, W., 2002. Late Devonian sea-level changes, cata-

strophic events, and mass extinctions. In: Koeberl, C., MacLeod, K.G. (Eds.),

Catastrophic Events and Mass Extinctions: Impacts and Beyond, Geological Society of

America, Special Papers 356, pp. 473–487.

Sanz-López, J., García-López, S., Montesinos, J.R., Arbizu, M., 1999. Biostratigraphy and

sedimentation of the vidrieros formation (middle Famennian–lower Tournaisian) in

the Gildar–Montó unit (northwest Spain). Boll. Soc. Paleontol. Ital. 37, 393–406.

Sartenaer, P., 1998. The presence in Morocco of the late Famennian genus Hadyrhyncha

Havlíĉek, 1979 (rhynchonellid, brachiopod). In: Bulletin de l'Institute Royal des

sciences naturelles de belgique, sciences de la terre. 68. pp. 115–120.

Sartenaer, P., 1999. Tetragonorhynchus, new late Famennian rhynchonellid genus from

Maïder, southern Morocco, and Tetragonorhynchidae n. fam. In: Bulletin de l'institute

royal des sciences naturelles de belgique, sciences de la terre. 69. pp. 67–75.

Sartenaer, P., 2000. Phacoiderhynchus, a new middle Famennian rhynchonellid genus

from the Anti-Atlas, Morocco, and Phacoiderhynchidae n. fam. In: Bulletin de l'in-

stitute royal des sciences naturelles de belgique, sciences de la terre. 70. pp. 75–88.

Seilacher, A., 1970. Begriff und Bedeutung der Fossil-Lagerstätten. N. Jb. Geol. Paläont.

1970 (1), 34–39.

Siegmund, H., Trappe, J., Oschmann, W., 2002. Sequence stratigraphic and genetic as-

pects of the Tournaisian ‘Liegender Alaunschiefer’ and adjacent beds. Int. J. Earth Sci.

91, 934–949.

Siveter, D.J., Vannier, J., Palmer, D., 1991. Silurian myodocopes: pioneer pelagic os-

tracodes and the chronology of an ecological shift. J. Micropalaeontol. 10, 151–173.

Sokiran, E.V., 2002. Frasnian–Famennian extinction and recovery of rhynchonellid bra-

chiopods from the east European platform. Acta Palaeontol. Pol. 47 (2), 339–354.

Spalletta, C., Perri, M.C., Over, D.J., Corradini, C., 2017. Famennian (Upper Devonian)

conodont zonation: revised global standard. Bull. Geosci. 92 (1), 31–57.

Struve, W., 1990. Beiträge zur Kenntnis der Phacopina (Trilobita), 18: Die Riesen-

Phacopiden aus dem Ma'der, SEmarokkanische Prä-Sahara. Senckenb. Lethaea 75 (1/

2), 77–129.

Termier, H., 1936. Etudes géologiques sur le Maroc central et le Moyen atlas septen-

trional. Notes et Mémoires Service des Mines et de la carte géologique du Maroc 33

1566p.

Tessitore, L., Naglik, C., De Baets, K., Galfetti, T., Klug, C., 2016. Neptunian dykes in the

Devonian carbonate buildup Aferdou El Mrakib (eastern Anti-Atlas, Morocco) and

implications for its growth. Neues Jahrb. Geol. Palaontol. Abh. 281 (3), 247–266.

Thayer, C.W., Steele-Petrovic, H.M., 1975. Burrowing of the lingulid brachiopod Glottidia

pyramidata: its ecological and paleoecologic significance. Lethaia 8, 209–221.

Vannier, J., Abe, K., 1993. Functional morphology and behaviour of Vargula hilgendorfii

(Ostracoda, Myodocopida). J. Crustac. Biol. 13, 51–76.

Vannier, J., Boissy, P., Racheboeuf, P.R., 1997. Locomotion in Nebalia bipes: a possible

model for Palaeozoic phyllocarid crustaceans. Lethaia 30, 89–104.

Walliser, O.H., 1996. Global events in the Devonian and Carboniferous. In: Walliser, O.H.

(Ed.), Global Events and Event Stratigraphy in the Phanerozoic, pp. 225–250.

Webster, G.D., Becker, R.T., Maples, C.G., 2005. Biostratigraphy, paleoecology, and

taxonomy of Devonian (Emsian and Famennian) crinoids from southeastern Morocco.

J. Paleontol. 79 (6), 1052–1071.

Wendt, J., 1985. Disintegration of the continental margin of northwestern Gondwana:

late Devonian of the eastern Anti-Atlas (Morocco). Geology 13, 815–818.

Wendt, J., 1995. Shell directions as a tool in palaeocurrent analysis. Sediment. Geol. 95,

161–186.

Wendt, J., Belka, Z., 1991. Age and depositional environment of Upper Devonian (early

Frasnian to early Famennian) black shales and limestones (Kellwasser facies) in the

eastern Anti-Atlas, Morocco. Facies 25, 51–90.

Wendt, J., Kaufmann, B., Belka, Z., Klug, C., Lubeseder, S., 2006. Sedimentary evolution

of a Palaeozoic basin and ridge system: the Middle and Upper Devonian of the Ahnet

and Mouydir (Algerian Sahara). Geol. Mag. 143 (3), 269–299.

Westermann, G.E.G., 1999. Life of habits of nautiloids. In: Savazzi, E. (Ed.), Functional

Morphology of the Invertebrate Skeleton. John Wiley and Sons, New York, pp.

263–298.

Westermann, G.E.G., Tsujita, C.J., 1999. Life habits of ammonoids. In: Savazzi, E. (Ed.),

Functional Morphology of the Invertebrate Skeleton. John Wiley and Sons, New York,

pp. 299–325.

Wignall, P.B., Simms, M.J., 1990. Pseudoplankton. Palaeontology 33, 359–378.

Williams, M.E., 1990. Feeding behavior in Cleveland shale fishes. In: Boucot, A.J. (Ed.),

Evolutionary Paleobiology of Behavior and Coevolution. Elsevier, Amsterdam, pp.

237–287.

Zatoń, M., Filipiak, P., Rakociński, M., Krawczyński, W., 2013. Kowala Lagerstätte: Late

Devonian arthropods and non-biomineralized algae from Poland. Lethaia 47 (3),

352–364.

Zatoń, M., Broda, K., Qvarnström, M., Niedźwiedzki, G., Ahlberg, P.E., 2017. The first

direct evidence of a Late Devonian coelacanth fish feeding on conodont animals. Sci.

Nat. 104 (26), 1–5. http://dx.doi.org/10.1007/s00114-017-1455-7.

Ziegler, W., Sandberg, C.A., 1984. Palmatolepis-based revision of upper part of standard

late Devonian conodont zonation. Geol. Soc. Am. Spec. Pap. 196, 179–194.

L. Frey et al.

46

Chapter I: Alpha Diversity and Palaeoecology

Supplementary material

Table S1. Primary data of invertebrate associations found in the Famennian at Madène el

Mrakib.

Association

Source of data Stratigraphic age Number of all species; only ammonoids genera

Groups in trophic nucleus

Modes of life

A (Fig. 4A-B, 5A)

Newly collected at Madène el Mrakib, housed at PIM

-lower Famennian -Ammonoids: Ammonoidea indet. 1 → Cheiloceras horizon

3; 1 -Brachiopods (1 taxa)

- Pelagic, slow-motile, predator - Surficial, non-motile attached,

suspension feeder

B (Fig. 4A-B, 5B)

Newly collected at Madène el Mrakib, housed at PIM

-lower Famennian -Ammonoids: Ch. (Staffites) afrispina → Cheiloceras horizone

4; 1 -Ammonoids (1 taxa) -Brachiopods (1 taxa)

-Pelagic, slow-motile, predator -Surficial, non-motile attached, suspension feeder -Semi-infaunal or surficial, non-motile, unattached, suspension feeder

C (Fig. 4A-B, 5C)

Newly collected at Madène el Mrakib, housed at PIM

-lower Famennian -Ammonoids: Ch. (Staffites) afrispina Armatites beatus Aulatornoceras sp. Torleyoceras sp. Falcitornoceras bilobatum falciculum → Cheiloceras horizon

12; 5 -Ammonoids (3 taxa) -Orthocerids (1 taxa)

-Pelagic, slow-motile, predator -Surficial, non-motile attached, suspension feeder -Benthic, no further details known

D (Fig. 4A-B, 5D)

Newly collected at Madène el Mrakib, housed at PIM

-middle Famennian -Ammonoids : Tornoceratidae → horizon ?

5; 2 -Orthocerids (1 taxa)

-Pelagic, slow-motile, predator -Surficial, non-motile attached, suspension feeder -Semi-infaunal or surficial, non-motile, unattached, suspension feeder

E (Fig. 4A-B, 5E)

Newly collected at Madène el Mrakib, housed at PIM

-middle Famennian -Ammonoids: Maeneceras acutolaterale → Maeneceras horizon

8; 2 -Phyllocarids (1 taxa)

-Pelagic, fast-motile, deposit feeder -Pelagic, slow-motile, predator -Surficial, facultatively motile, unattached, suspension feeder -Semi-infaunal or surficial, non-motile, unattached, suspension feeder -Benthic, no further details known

F (Fig. 4A-B, 5F)

Newly collected at Madène el Mrakib, housed at PIM

-middle Famennian -Ammonoids : Sporadoceras sp. → horizon?

11; 1 -Brachiopods (1 taxa) -Bivalves (1 taxa) -Orthocerids (1 taxa)

-Pelagic, slow-motile, predator -Erected, non-motile attached, suspension feeder -Surficial, facultatively motile, attached, suspension feeder -Surficial, non-motile attached, suspension feeder -Semi-infaunal or surficial, non-motile, unattached, suspension feeder -Shallow infaunal, facultatively motile, unattached, suspension feeder -Benthic, no further details known

G (Fig. 4A-B, 5G)

Newly collected at Madène el Mrakib, housed at PIM

-middle Famennian -Ammonoids : Planitornoceras pugnax Erfoudites sp. → Planitornoceras horizon

9; 2 -Ammonoids (1 taxa) -Orthocerids (1 taxa)

-Pelagic, slow-motile, predator -Surficial, slow-motile, grazer -Surficial, facultatively motile, unattached, suspension feeder -Surficial, non-motile attached, suspension feeder -Semi-infaunal or surficial, non-motle, unattached, suspension feeder -Benthic, no further details known

47

Chapter I: Alpha Diversity and Palaeoecology

Association

Source of data Stratigraphic age Number of all species; only ammonoids genera

Groups in trophic nucleus

Modes of life

H (Fig. 4A-B, 5H)

Newly collected at Madène el Mrakib, housed at PIM

-middle Famennian -Ammonoids: Planitornoceras pugnax Erfoudites spiriferus Pseudoclymenia sp. → Planitornoceras horizon

14; 4

-Ammonoids (1 taxa) -Orthocerids (1 taxa) -Brachiopods (2 taxa)

-Pelagic, slow-motile, predator -Surficial, non-motile attached, predator -Surficial, non-motile attached, suspension feeder -Semi-infaunal or surficial, facultatively motile, unattached, suspension feeder -Semi-infaunal, non-motile, unattached, suspension feeder -Shallow infaunal, facultatively motile, unattached, suspension feeder

I (Fig. 4A-B, 5I)

Newly collected at Madène el Mrakib, housed at PIM

-Upper Famennian (Annulata Black Shales) -Ammonoids : Platyclymenia annulata → Platyclymenia horizon

2; 1

-Ammonoids (1 taxa)

-Pelagic, slow-motile, predator

J (Fig. 7, Table S3)

Madène el Mrakib, partially published in Korn et al. (2014, 2015a) housed at MNB

-Upper Famennian

-Ammonoids: → Platyclymenia horizon

NA; 5

-Ammonoids (2 taxa)

-Pelagic, slow-motile, predator

K (Fig. 4A-B, 5J)

Newly collected at Madène el Mrakib, housed at PIM

-Upper Famennian -Ammonoids : Playtclymenia sp. Prionoceras lamellosum and lentis Cyrtoclymenia sp. Procymaclymenia ebbighauseni Erfoudites rherisensis Sporadocers cf. muensteri → Platyclymenia/ Procymaclymenia horizon

22; 6 -Ammonoids (7 taxa) -Orthocerids (1 taxa)

-Pelagic, slow-motile, predator -Surficial, slow-motile, grazer -Surficial, facultatively motile, unattached, suspension feeder -Surficial, non-motile attached, suspension feeder -Semi-infaunal or surficial, non-motile, unattached, suspension feeder -Shallow infaunal, facultatively motile, unattached, suspension feeder

L (Fig. 7, Table S3)

Madène el Mrakib, partially published in Korn et al. (2014, 2015a), housed at MNB

-Upper Famennian - Ammonoids: → Platyclymenia/ Procymaclymenia horizon

NA; 7 -Ammonoids (5 taxa)

-Pelagic, slow-motile, predator

M (Fig. 7, Table S3)

Madène el Mrakib, partially published in Korn et al. (2014, 2015a), housed at MNB

-Upper Famennian -Ammonoids: →Platyclymenia/ Procymaclymenia horizon

NA; 7 -Ammonoids (4 taxa)

-Pelagic, slow-motile, predator

N (Fig. 7, Table S3)

Madène el Mrakib, partially published in Korn et al. 2014, 2015a), housed at MNB

-Uppermost Famennian -Ammonoids : → Gonioclymenia horizon

NA; 7 -Ammonoids (7 taxa)

-Pelagic, slow-motile, predator

O (Fig. 7. Table S3)

Madène el Mrakib, partially published in Korn et al. (2014, 2015a), housed at MNB

-Uppermost Famennian -Ammonoids: → Kalloclymenia to Wocklumeria horizon

NA; 1 -Ammonoids (6 taxa)

-Pelagic, slow-motile, predator

P (Fig. 4A-B, 5K)

Newly collected at Madène el Mrakib, housed at PIM

-Uppermost Famennian -Ammonoids: → Wocklumeria horizon

7; 1? -Ammonoids (1 taxa) -Orthocerids (1 taxa) -Trilobites (1 taxa)

-Pelagic, slow-motile, predator -Surficial, fast-motile, suspension feeder/predators -Surficial, slow-motile -Surficial, non-motile attached, suspension feeder

Q (Fig. 4A-B, 5L)

Newly collected at Madène el Mrakib, housed at PIM

-Uppermost Famennian (Hangenberg Black Shales); -Ammonoids: Postclymenia calceola Mimimitoceras sp. Acutimitoceras sp. Tornoceratoidea → Postclymenia horizon

11; 4

-Bivalves (1 taxa) - Cephalopods (2 taxa)

-Pelagic, slow-motile, predator -Surficial, non-motile attached, suspension feeder

48

Chapter I: Alpha Diversity and Palaeoecology

Table S2. Primary data of invertebrate associations found in the Tournaisian at Aguelmous

(according to Ebbighausen and Bockwinkel, 2007).

Association

Source of data Stratigraphic age Number of all species; only ammonoids genera

Groups in the trophic nucleus

Modes of life

R (Fig. 6A) Aguelmous, Bed 2 in Ebbighausen and Bockwinkel (2007), housed at MNB

-Lower Tournaisian -Ammonoids: Acutimitoceras intermedium Acutimitoceras sarahae Acutimitoceras endoserpens Acutimitoceras algeriense Acutimitoceras posterum Acutimitoceras pentaconstrictum Acutimitoceras hollardi Acutimitoceras depressum Acutimitoceras occidentale Acutimitoceras mfisense Costimitoceras aitouamar Imitoceras oxydentale Weyerella sp. Eocanites simplex Kazakhstania nitida Kazakhstania evoluta Kornia citrus Gattendorfia jacquelinae → Gattendorfia/ Kahlacanites horizon

32; 8 -Ammonoids (4 taxa) -Gastropods (1 taxa)

-Pelagic, slow-motile, predator -Surficial, slow-motile, grazer -Surficial, non-motile attached, predator -Surficial, non-motile attached, suspension feeder -Benthic, no further details known

S (Fig. 6B) Aguelmous, Bed 12 in Ebbighausen and Bockwinkel (2007), housed at MNB

-Lower Tournaisian -Ammonoids: Acutimitoceras algeriense Gattendorfia ihceni Gattendorfia jacquelina → Gattendorfia/ Kahlacanites horizon

8; 2 -Ammonoids (3 taxa)

-Pelagic, slow-motile, predator -Surficial, slow-motile, grazer -Benthic, no further details known

T (Fig. 6C) Aguelmous, Bed 16 in Ebbighausen and Bockwinkel (2007), housed at MNB

-Lower Tournaisian -Ammonoids: Kahlacanites mariae Kahlacanites meyendorffi Gattendorfia debouaaensis Gattendorfia gisae Gattendorfia jacquelinae Hasselbachia arca Hassdelbachia gourara Acutimitoceras algeriense Eocanites sp. Becanites sp. → Gattendorfia/ Kahlacanites horizon

15; 6 -Ammonoids (6 taxa)

-Pelagic, slow-motile, predator

U (Fig. 6D) Aguelmous, Bed 18 in Ebbighausen and Bockwinkel (2007), housed at MNB

-middle Tournaisian -Ammonoids: Acutimitoceras sp. Protocanites hollardi Globimitoceras rharrizense Imitoceras sp. Gattendorfia sp. Goniocyclus elatrous Eocanites → Goniocyclus horizon

9; 7 -Ammonoids (4 taxa)

-Pelagic, slow-motile, predator

49

Chapter I: Alpha Diversity and Palaeoecology

Figure S1. Relative abundances of species occurring in the Maïder region (Morocco); red

bars represent the dominant species of the association. Diversity corresponding with the

Wocklumeria Stage of Madène el Mrakib, 7 taxa (excluding crinoids and bioturbation) are

depicted.

Figure S2. Rarefaction tests of Famennian and Tournaisian associations including all

invertebrate groups; blue lines represent confidential intervals; red lines show how many taxa

would have been theoretically sampled with further collection of specimens; green line: how

many taxa would have been theoretically sampled within 90 specimens.

50

Chapter I: Alpha Diversity and Palaeoecology

51

Chapter I: Alpha Diversity and Palaeoecology

Figure S3. Rarefaction tests of Famennian and Tournaisian ammonoid associations

containing at least three taxa; blue lines represent confidential intervals; red lines show how

many taxa would have been theoretically sampled with further collection of specimens.

52

Chapter I: Alpha Diversity and Palaeoecology

53

Chapter I: Alpha Diversity and Palaeoecology

Tab

le S3. R

aw data of F

amennian invertebrate sam

ples collected at Madène el M

rakib (northeastern Anti-A

tlas, Morocco).

Class

Species

Mode of life

Association A

Association B

Association C

Association D

Association E

Association F

Association G

Association H

Association I

Association J

Association K

Association L

Association M

Association N

Association O

Association P

Association Q

Association R

Association S

Association T

Association U

Cephalo

poda

Orth

oce

rida in

det. 1

p, fs

, pr

3

47

38

86

14

15

67

31

2

19

3

Orth

oce

rida in

det. 2

p, fs

, pr

1

Orth

oce

rida in

det. 3

(Murc

his

onic

era

s)

p, fs

, pr

2

Orth

occe

rida in

det. 4

p, fs

, pr

49

14

9

Orth

oce

rida in

det. 5

p, fs

, pr

4

Orth

oce

rida in

det. 6

p, fs

, pr

3

Spyro

cera

s s

p.

p, fs

, pr

3

Ba

ctritid

ae

ind

et.

p, fs

, pr

1

2

1

Am

monoid

ea in

det. 1

p, fs

, pr

2

Am

monoid

ea in

det. 2

p, fs

, pr

3

Am

monoid

ea in

det. 3

p, fs

, pr

2

Am

monoid

ea in

det. 4

p, fs

, pr

1

Am

monoid

ea in

det. 5

p, fs

, pr

7

Am

monoid

ea in

det. 6

p, fs

, pr

Torn

ocera

toid

ea

p, fs

, pr

1

5

Falc

itorn

ocera

s fa

lcic

ulu

m

p, fs

, pr

2

Falc

itorn

ocera

s b

ilobatu

m

p, fs

, pr

6

Au

lato

rno

cera

s s

p.

p, fs

, pr

16

Pla

nito

rnocera

s p

ugnax

p, fs

, pr

231

36

Arm

atite

s b

eatu

s

p, fs

, pr

21

54

Chapter I: Alpha Diversity and Palaeoecology

Pse

ud

ocly

me

nia

sp.

p, fs

, pr

1

Pro

cym

acly

menia

ebbig

hauseni

p, fs

, pr

6

Torle

yocera

s s

p.

p, fs

, pr

1

Ch. (S

taffite

s) a

frispin

a

p, fs

, pr

160

56

Mae

ne

ce

ras a

cu

tola

tera

le

p, fs

, pr

1

Spora

docera

s s

p.

p, fs

, pr

1

Sp

ora

doce

ras m

uenste

ri p, fs

, pr

1

58

Sp

ora

doce

ras g

lobu

losu

m

p, fs

, pr

11

Spora

docera

s c

onfo

rme

p, fs

, pr

1

Erfo

ud

ites rh

eris

ensis

p, fs

, pr

2

210

10

Erfo

ud

ites s

pirife

rus

p, fs

, pr

2

Erfo

ud

ites s

p.

p, fs

, pr

1

Prio

nocera

s le

ntis

p, fs

, pr

356

37

Prio

nocera

s la

mello

sum

p, fs

, pr

1752

17

Prio

nocera

s v

etu

s

p, fs

, pr

34

Prio

nocera

s ta

khbtite

nse

p, fs

, pr

16

Prio

nocera

s m

rakib

ense

p, fs

, pr

138

Prio

nocera

s o

uaro

uro

ute

nse

p, fs

, pr

61

Prio

nocera

s s

ubtu

m

p, fs

, pr

3

Pro

tacto

cly

me

nia

sp. 2

p, fs

, pr

1

3

Pro

tacto

cly

me

nia

di

p, fs

, pr

10

Pro

tacto

cly

me

nia

du

p, fs

, pr

3

11

Cyrto

cly

menia

sp. 1

p, fs

, pr

6

Pla

tycly

me

nia

an

nula

ta

p, fs

, pr

100

Pla

tycly

me

nia

sp

. 2

p, fs

, pr

74

38

Pla

tycly

me

nia

sp

. p, fs

, pr

6

Pla

tycly

me

nia

ibnsin

ai

p, fs

, pr

5

Pla

tycly

me

nia

xxP

ls

p, fs

, pr

30

55

Chapter I: Alpha Diversity and Palaeoecology

Pla

tycly

me

nia

xxP

li p, fs

, pr

23

49

Pla

tycly

me

nia

xxP

lv

p, fs

, pr

4

Pla

tycly

me

nia

xxP

lg

p, fs

, pr

6

8

Pla

tycly

me

nia

a-i

p, fs

, pr

28

4

Pla

tycly

me

nia

inv

p, fs

, pr

24

31

Pla

tycly

me

nia

evo

p, fs

, pr

6

Pla

tycly

me

nia

um

b

p, fs

, pr

3

Po

stc

lym

en

ia c

alc

eo

la

p, fs

, pr

33

Cym

acly

en

ia s

ub

vexa

p, fs

, pr

79

Cym

acly

en

ia fo

rmosa

p, fs

, pr

16

Cym

acly

en

ia la

mb

idia

p, fs

, pr

15

Cym

acly

en

ia c

arn

ata

p, fs

, pr

1

Mim

imito

cera

s s

p.

p, fs

, pr

22

Mim

imito

cera

s c

arn

atu

m

p, fs

, pr

78

Mim

imito

cera

s c

om

tum

p, fs

, pr

59

Acutim

itoce

ras s

p. 3

p, fs

, pr

2

Acutim

itoce

ras s

p. 4

p, fs

, pr

1084

73

17

83

Acutim

itoce

ras s

p. A

p, fs

, pr

19

Acutim

itoce

ras h

olla

rdi

p, fs

, pr

18

Acutim

itoce

ras in

term

ed

ium

p, fs

, pr

292

Acutim

itoce

ras o

ccid

en

tale

p, fs

, pr

43

Acutim

itocera

s d

epre

ssum

p, fs

, pr

16

Acutim

itoce

ras s

ara

ha

e

p, fs

, pr

171

Acutim

itoce

ras m

fise

nse

p, fs

, pr

9

Acutim

itoce

ras e

ndose

rpe

ns

p, fs

, pr

119

Acutim

itoce

ras a

lgerie

nse

p, fs

, pr

1

17

5

Acutim

itocera

s p

oste

rum

p, fs

, pr

1

Acutim

itoce

ras p

enta

constric

tum

p, fs

, pr

1

56

Chapter I: Alpha Diversity and Palaeoecology

lmito

cera

s o

xydenta

le

p, fs

, pr

32

lmito

cera

s s

p.

p, fs

, pr

21

Gatte

ndorfia

jacquelin

ae

p, fs

, pr

5

2

9

Gatte

ndorfia

debouaaensis

p, fs

, pr

35

Gatte

ndorfia

lhceni

p, fs

, pr

28

Gatte

ndorfia

gis

ae

p, fs

, pr

21

Ga

tten

do

rfia s

p. 1

p, fs

, pr

10

Ga

tten

do

rfia s

p. 2

p, fs

, pr

18

21

Eo

ca

nite

s s

imp

lex

p, fs

, pr

14

Eo

ca

nite

s s

p. 1

p, fs

, pr

2

Eo

ca

nite

s s

p. 2

p, fs

, pr

1

3

1

Glo

bim

itoce

ras rh

arrh

izen

se

p, fs

, pr

32

Costim

itocera

s a

itouam

ar

p, fs

, pr

49

Ha

sse

lba

chia

gou

rara

p, fs

, pr

2

Ha

sse

lba

chia

arc

a

p, fs

, pr

25

Hasselb

achia

sp.

p, fs

, pr

3

Ko

rnia

citru

s

p, fs

, pr

7

Ka

zakh

sta

nia

evo

luta

p, fs

, pr

5

Ka

zakh

sta

nia

nitid

a

p, fs

, pr

13

Go

nio

cyclu

s e

latro

us

p, fs

, pr

9

Be

ca

nite

s s

p.

p, fs

, pr

1

Ka

hla

can

ites m

aria

e

p, fs

, pr

52

Ka

hla

can

ites m

eyen

do

rffi p, fs

, pr

1

Ka

hla

can

ites s

p.

p, fs

, pr

55

Pro

toca

nite

s h

olla

rdi

p, fs

, pr

64

Weyere

lla s

p.

p, fs

, pr

24

Trig

onocly

menia

sp.

p, fs

, pr

5

Pro

toxycly

me

nia

we

nd

ti p, fs

, pr

9

Nanocly

menia

sp.

p, fs

, pr

10

57

Chapter I: Alpha Diversity and Palaeoecology

Pro

cym

acly

menia

ebbig

hauseni

p, fs

, pr

98

Unguspora

docera

s u

nguifo

rme

p, fs

, pr

8

Gundolfic

era

s v

escum

p, fs

, pr

3

Po

stto

rno

cera

s e

ega

ntu

m

p, fs

, pr

3

Alp

inite

s s

ch

ultze

i p, fs

, pr

1

Ebbig

hausenite

s w

eyeri

p, fs

, pr

1

Dis

cocly

me

nia

atla

nte

a

p, fs

, pr

2

Alp

inite

s zig

zag

p, fs

, pr

1

Gonio

cly

menia

wendti

p, fs

, pr

17

Gonio

cly

menia

ali

p, fs

, pr

10

Gonio

cly

menia

spin

iger

p, fs

, pr

1

Kosm

ocly

meniid

ae in

det.

p, fs

, pr

26

Kosm

ocly

menia

sp.

p, fs

, pr

1

Biv

alv

ia

Biv

alv

ia in

det. 1

benth

ic

1

Biv

alv

ia in

det. 2

benth

ic

2

Biv

alv

ia in

det. 3

benth

ic

1

Biv

alv

ia in

det. 4

benth

ic

1

2

Biv

alv

ia in

det. 5

benth

ic

1

Biv

alv

ia in

det. 6

benth

ic

1

Biv

alv

ia in

det. 7

benth

ic

2

Biv

alv

ia in

det.8

benth

ic

1

Biv

alv

ia in

det. 9

benth

ic

3

Biv

alv

ia in

de

t. 11 (n

ucu

lid)

benth

ic

6

Biv

alv

ia in

det. 1

2

benth

ic

1

Biv

alv

ia in

det. 1

0

benth

ic

3

Biv

alv

ia in

det. 1

3

benth

ic

1

Bu

ch

iola

(Bu

ch

iola

) sp.

sm

i/su,n

u, s

f 2

8

3

2

1

Gly

pto

ha

llica

rdia

sp.

sm

i/su, n

u, s

f 3

3

Gueric

hia

cf. v

enusta

su

, na, s

f 3

5

4

1

3

58

Chapter I: Alpha Diversity and Palaeoecology

Gueric

hia

ellip

tica

su

, na, s

f

280

Pro

soch

asm

a s

p.

su, fa

, sf

34

Op

isth

oco

elu

s s

p.

su, fa

, sf

1

1

?M

etro

ca

rdia

sp.

si, fu

, sf

3

Lo

xo

pte

ria s

p.

su, fu

, sf

1

?P

tych

opte

ria s

p.

su, fa

, sf

3

?S

treb

lop

teria

sp.

su, fa

, sf

3

Pala

eoneilo

sp

. si, fu

, df

2

3

Am

phig

astro

poda

Belle

rophon (A

gla

ogly

pta

) su

, fs, g

2

Belle

rophontid

ae in

det.

su

, fs, g

7

Gastro

poda

Gastro

poda in

det. 1

su

, fs, g

3

Gastro

poda in

det. 2

su

, fs, g

2

6

Gastro

poda in

det. 3

su

, fs, g

60

Gastro

poda in

det. 4

su

, fs, g

9

Gastro

poda in

det. 5

su

, fs, g

58

Gastro

poda in

det. 6

su

, fs, g

2

Gastro

poda in

det. 7

su

, fs, g

1

Macro

ch

ilina s

p.

su

, fs, g

1

Rhynchonella

ta

Rhynchonella

ta in

det. 1

su

, na, s

f 1700

Rhynchonella

ta in

det. 2

su

, na, s

f 122

1

Rhynchonella

ta in

det. 3

su

, na, s

f 5

39

12

3

4

Rhynchonella

ta in

det. 4

su

, na, s

f 3

3

Rhynchonella

ta in

det. 5

4

Phacoid

erh

ynchus a

ntia

tlasic

us

su

, na, s

f 4

Au

lace

lla s

p.

su

, na, s

f 1

Sp

iriferid

a

Spirife

rida in

det.

su

, na, s

f

1

Lin

gula

ta

Lin

gula

ta in

det.

si, n

a, s

f 3

Bra

ch

iop

od

a

Bra

ch

iop

od

a in

det. 1

13

59

Chapter I: Alpha Diversity and Palaeoecology

Ph

yllo

ca

rida

Ph

yllo

ca

rida

inde

t p, ff, d

f 151

Trilo

bita

T

rilobita

indet.

su

, ff, pr/d

f 7

Crin

oid

ea

Crin

oid

ea in

det.

er, n

a, s

f 1

Tabula

ta

Tabula

ta in

det.

su

, na, s

f

1

Rugosa

Rugosa in

det. 1

su

, na, p

r 2

Rugosa in

det. 2

su

, na, p

r

6

Rugosa in

det. 3

su

, na, p

r 1

Bry

ozo

a

Bry

ozo

a in

det

su

, na, s

f 5

CHAPTER II

Fossil-Lagerstätten and preservation of invertebrates and vertebrates from the Devonian in the eastern Anti-Atlas

(Morocco)

Linda Frey, Alexander Pohle, Martin Rücklin and Christian Klug

Submitted to : Lethaia

63

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Fossil-Lagerstätten and preservation of invertebrates and vertebrates from the Devonian in the eastern Anti-Atlas (Morocco)

LINDA FREY, ALEXANDER POHLE, MARTIN RÜCKLIN and CHRISTIAN KLUG

Frey, L., Pohle, A., Rücklin, M. & Klug, C. 20XX. Fossil-Lagerstätten and preservation of vertebrates and invertebrates from the Moroccan Devonian (eastern Anti-Atlas). Lethaia.

Throughout the Devonian, fossil invertebrates are abundant in the eastern Anti-Atlas and depending on the strata, they display a high taxonomic diversity. Fossils of jawed vertebrates have been recorded after the early Lochkovian so far and are relatively common with their abundance and diversity increasing towards the Late Devonian. Fossil preservation varies strongly, partially refl ecting the disintegration of the continental shelf of Gondwana in this region in three epicontinental basins and pelagic ridges during the Devonian and fl uctuations of the regional sea-level. We analyzed the mineral composition of several invertebrate and vertebrate samples of Devonian and Early Carboniferous age by Raman spectroscopy and X-ray diffraction. We use the results of these analyses combined with palaeogeographic and palaeoecological data to interpret the genesis of Devonian Fossil-Lagerstätten of this region. Accordingly, we list eight examples of the numerous Devonian Konzentrat-Lagerstätten and two examples of Konservat-Lagerstätten with soft-tissue preservation (the Famennian Thylacocephalan Layer and the Hangenberg Black Shale of the southern Maïder). The latter are the fi rst two of this kind of Fossil-Lagerstätte from the Devonian of North Africa. The taphonomic and oceanic settings suggest that these Konservat-Lagerstätten formed due to stagnation (perhaps related to vertical restriction of water exchange and water depth rather than limited spatial water exchange and a lateral restriction) in the relatively small Maïder Basin with limited water exchange with the neighboring Tafi lalt Basin. The poor lateral or vertical water exchange could also explain the reduced chondrichthyan diversity compared to the Tafi lalt Platform, where the water was shallower and probably better oxygenated at depth. □ Exceptional preservation, Raman-spectroscopy, X-ray Diffraction, mineralogy, weathering, Chondrichthyes, Placodermi, Ammonoidea.

Linda Frey [linda.frey@pim.uzh.ch], Alexander Pohle [alexander.pohle@pim.uzh.ch], Christian Klug [chklug@pim.uzh.ch], Paläontologisches Institut und Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zürich, Switzerland; Martin Rücklin [martin.rucklin@naturalis.nl], Naturalis Biodiversity Center, Postbus 9517, NL-2300 RA Leiden, the Netherlands.

Two fi elds of research concerning the palaeontology of the Devonian in Morocco have been explored only rarely yet: Fossil-Lagerstätten and taphonomy. The term Fossil-Lagerstätten (Seilacher 1970) applies to deposits where fossils occur either in a very high abundance or in exceptional preservation including soft tissues and articulated skeletons; both cases occur in the eastern Anti-Atlas as we demonstrate here, although the former kind is much more common than the latter. Therefore, we put a special emphasis on two poorly documented Famennian cases of the latter kind (Konservat-Lagerstätten). In order to understand the formation of Fossil-Lagerstätten, we follow three approaches: it is essential to examine and understand the taphonomic processes that are involved (approach 1), the palaeogeographic setting (approach 2) and the palaeo-environmental conditions (approach 3).

Taphonomic processes (approach 1) can partially be reconstructed using information from the mode of preservation and also the mineralogy

of the fossils under consideration. Based on the colour, host sediments and surface patterns, preservation in a series of different minerals is inferred for vertebrate and invertebrate fossils from the arid eastern Anti-Atlas (Fig. 1). Although their actual mineralogical composition was rarely tested (e.g., Klug et al. 2009, 2016), the mineralogy of the respective fossil is inferred commonly based rather on speculation than actual mineralogical examinations (e.g., Pohle & Klug 2018). Consequently, the analysis of the mineral composition of fossils of various ages and localities from the Devonian of the Anti-Atlas is crucial. Here, we discuss possible implications of fossil preservation for palaeoenvironment reconstruction and interpretations of the taphonomy and consider possible secondary alteration due to weathering. Based on taphonomic, palaeogeographic and facies data, palaeoenvironment and palaeoecology are reconstructed and the infl uence on the vertebrate diversity is analysed.

The study of taphonomy is of interest because only in the Maïder Basin, chondrichthyans

64

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

preserving cartilaginous body parts as well as soft tissues have been discovered. Hence, the new data on preservation will shed light on how the Konservat-Lagerstätten of the Maïder region formed (Klug et al. 2016; Frey et al. 2018).

The second approach to understand the formation of Fossil-Lagerstätten is the study of the palaeogeographic setting and facies. Fortunately, the arid climate keeps vegetation to a minimum in the Moroccan pre-Sahara, thus creating formidable outcrops. Therefore, facies changes can be examined in space and through geologic time in order to reconstruct the arrangement of basins and carbonate ramps with ridge and swell topography, and the approximate situation of coastlines throughout the Devonian (e.g., Hollard 1974; Wendt 1985, 1988; Wendt and Belka 1991; Kaufmann 1998; Döring and Kazmierczak 2001; Lubeseder et al. 2010). Since the required palaeogeographic data are readily available from

the literature, we do not add new details to this aspect, but provide a brief review necessary for the interpretation of the Lagerstätten type.

In our third approach, we qualitatively assess the palaeo-environment and palaeoecology through the Devonian of the eastern Anti-Atlas. Devonian sedimentary sequences of this region contain numerous different facies types and thus also various kinds of sediments with a broad range of vertebrate, invertebrate and plant fossils (e.g., Clariond 1936; Termier and Termier 1950; Lehman 1956, 1964, 1976, 1977; Lelièvre and Janvier 1986, 1988; Belka et al. 1999; Derycke 1992; Becker et al. 2000; Rücklin 2010, 2011; Frey et al. 2014; Rücklin et al. 2015; Korn et al. 2016a, b; Rücklin and Clément 2017). In the Famennian of the eastern Anti-Atlas, fossil invertebrates but also vertebrates can be found in sometimes impressive numbers. As far as vertebrates are concerned, microremains of gnathostomes are quite common

Fig. 1. Geologic map of the eastern Anti-Atlas of the Maïder and Tafi lalt Basins as well as the Tafi lalt Platform. Only some examples of vertebrate occurrences of the Famennian are given: arthodire remains can be found in almost every larger outcrop of the Famennian in this region.

65

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

in some strata (Derycke 1992; Ginter et al. 2002; Derycke et al. 2008) due to condensed sedimentation, particularly in the Tafi lalt. In the latter region, chondrichthyan diversity can be reasonably high (up to nine species in one layer). By contrast, in the Famennian of the southern Maïder Basin, chondrichthyan diversity appears to be lower (four to fi ve species) and some genera have not been found there yet although they are documented from the neighbouring Tafi lalt Basin (Ginter et al. 2002; Derycke et al. 2008).

Invertebrates, however, can usually deliver more detailed information on palaeoecology, partially because they often occur in statistically relevant numbers to carry out quantitative analyses. Several groups of invertebrates are very common in Devonian strata of the eastern Anti-Atlas. It is thus not surprising that some of the carbonate build-ups contain abundant corals (e.g., Kaufmann 1998; Berkowski 2006) and brachiopods (Halamski and Baliński 2013; Tessitore et al. 2013). Similarly, ammonoids are common from the Emsian to the Visean (e.g., Klug 2001; De Baets et al. 2013; Korn et al. 2007, 2016a, b) and occur in an impressive diversity, but their modes of preservation are almost as diverse. Other groups such as trilobites, crinoids, bivalves etc. occur as well, sometimes in vast numbers, but these were examined only in the palaeoecological context and not for their preservation. In this approach, we also rely on published data, which are briefl y summarized.

In this article, we address the following questions: (1) What is the mineral composition of invertebrate and vertebrate fossils in the Devonian of the eastern Anti-Atlas? (2) Is this composition primary or altered by taphonomic or weathering processes? (3) What can we deduce from the palaeogeographic setting for the formation of Fossil-Lagerstätten? (4) What are the implications derived from the preservational mode for the palaeoenvironment and the according differences in faunal composition? (5) What kinds of Fossil-Lagerstätten occur in the Anti-Atlas?

Material and methods

Material

All specimens (except one) were collected by the authors in the eastern Anti-Atlas. We chose the samples with the intention to include a broad range of different preservations in order to cover the main minerals occurring in fossils of the eastern Anti-Atlas. Most of these specimens are kept at the Paläontologisches Institut und Museum of the University of Zurich with numbers with the abbreviation PIMUZ. Some specimens are

stored at the Institut für Geowissenschften at the University of Tübingen with the abbreviation GPIT.

Mineral analyses

We analysed 30 samples (Tab. 1, 2) taken from invertebrates and vertebrates of mostly Devonian age (two from the Early Carboniferous) from the Maïder and the Tafi lalt (eastern Anti-Atlas). Table 1 and 2 show details and the mineral composition. Fossil preservation was examined by analysing their mineral composition using Raman spectroscopy and XRD (X-ray Diffraction) at the Swiss Federal Institute of Technology in Zurich (ETHZ).

Raman spectroscopy was performed with a DILOR LabRam (with built-in Olympus BX 40 microscope); grating was 600 or 1800 grooves/ mm, CCD sensor resolution 1152*298 pixels spectral resolution 1.3 – 1.5 cm-1 (for 1800 grating). Laser wavelength was 532.14 nm (with max. 500 mW laser power at the source) generated by a DPSS laser (Diode-pumped solid-state lasers). Measurements of laser Power were performed with a COHERENT LaserCheck hand-held device at 40% (Laser power: 195 mW at source, 19.7 mW with 100x, 26 mW with 50x on the sample). For the analyses of the spectra, we used the software CrystalSleuth (Laetsch & Downs 2006) and the American Mineralogist Crystal Structure Database (Downs & Hall-Wallace 2003). Some of the minerals rich in iron could not be measured properly, because the laser in use is red and too close in wavelength to that refl ected by these minerals.

For the XRD, we used a D8-advance (Bruker AXS) diffractometer in the Geochemistry and Petrology Laboratories of the ETHZ. All samples were crushed in an Agate bowl prior to analysis and the resulting fi ne powder was then prepared on sample holders. The diffractometer operated at 40 mA and 40 kV with Cu Kα radiation at room temperature (25°C). A scintillation counter with secondary monochromator was used to identify the minerals. The scans were performed as θ-2θ locked with a step size of 0.02° and step time of 1.0 s between 5°-90°2θ. In several cases of the minerals rich in iron, crystal-size was possibly too small to be well-analyzed by XRD, hence the often noisy signal seen in the analyses.

Comparison of Konservat-Lagerstätten

In order to better classify the Konservat-Lagerstätten of the Maïder (Thylacocephalan Layer, erroneously dubbed Phyllocarid Layer before, Hangenberg Black Shale), we used the questionnaire proposed by Seilacher et al.

66

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

(1985). This questionnaire represents a list of characteristics grouped into aspects of the sedimentary basin, stratigraphy, sedimentology, geochemistry (here, we excluded some characteristics because of missing data from most Konservat-Lagerstätten), taxonomic composition,

ecology, taphonomy, and diagenesis. We did not code (1) the setting, because all are marine, (2) the origin, because all are sedimentary, (3) the isotopy, because of missing data from many of the localities, (4) terrestrial organisms, because of the marine setting, and (5) articulation, because

Tab. 1. Results of Raman-analyses of various Devonian and Carboniferous fossils from the eastern Anti-Atlas.

Tab. 2. Results of XRD-analyses of various Devonian fossils from the eastern Anti-Atlas. Samples kept under the number PIMUZ 36879.

67

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

all localities yielded articulated specimens. We slightly reduced their list to 31 characters. The completed questionnaire for both Konservat-Lagerstätten of the eastern Anti-Atlas (Appendix 1) and for 19 well-known marine Konservat-Lagerstätten (Tab. 3) are added. Characters were coded as follows:Marine basin size: 0 ‒ ≤ 1 km2; 0.5 ‒ 1 to 10 km2; 1 ‒ ≥ 10 km2 Facies: 0 ‒ limestone; 1 ‒ clastics Palaeolatitude: 0 ‒ tropical; 1 ‒ moderateThickness: 0 ‒ ≥ 1 m; 0.5 ‒ 1 to 10 m; 1 ‒ ≤ 10 mDuration: 0 ‒ ≥ 1 Ma; 0.5 ‒ 1 to 10 Ma; 1 ‒ ≤ 10 MaSea-level: 0 ‒ ≥ 10 m; 0.5 ‒ 10 to 100 m; 1 ‒ ≤ 100 mSediment structures: 0 ‒ lamination; 1 ‒ ripple marksFauna: 0 ‒ invertebrates dominant; 1 ‒ vertebrates common;Pelagics (macrofossils): 0 ‒ mostly nekton; 1‒ mostly plankton.The following characters were coded as 0 when absent and as 1 when present:Pyrite in sediment; trace fossils; infauna; epibenthos; death marches; landing marks; soft tissue preservation; cuticles; roll marks; current alignment of fossils; aragonite preservation; pyrite internal moulds; concretions; deformation (compaction); carbonization; phosphatisation; pyritisation of tissues; tissues replaced by clay minerals; silicifi cation; obrution (tempestites or turbidites etc.); stagnation (phases of low oxygen); bacterial/ algal mats preserving fossils. The matrix was analysed in PAST (Hammer et al. 2001) by a Principal Component Analysis on the correlation matrix.

Mineralogy of fossil groups

All analyses are shown in Tab. 1 and 2. Correspondingly the method used for each analysis is indicated there. Therefore, no individual indication whether the mineral content was determined by XRD or Raman is given.

Invertebrates

In the Devonian limestones of the eastern Anti-Atlas, cephalopod remains usually occur as limestone internal moulds and occasionally shells are replaced with calcite. Near faults and the angular disconformity contact of the Cenomanian transgression, the fossils are often slightly dolomitized (Fig. 2L). Many clayey intervals yield internal moulds of cephalopods that are preserved in iron oxides and hydroxides (Fig. 2B, C, J). Their reddish colour made the determination

of the mineral content by Raman-spectroscopy impossible, but the XRD-analyses (Tab. 2) proved that particularly the black internal moulds of cephalopods are composed predominantly of goethite. More reddish specimens contain additionally haematite. These goethitic internal moulds sometimes contain remains of a pyritic core. This indicated already, that all these goethitic internal moulds derive from pyritic specimens (this is corroborated by pseudomorphoses of goethite after pyrite), where the iron of the pyrite was slowly oxidized in the course of the deep weathering of the clay sediments. Further corroboration of this scenario is provided by a specimen of Cymaclymenia (Fig. 2A), which was found in a depth of about ten meters in a well. Its pyritic composition was determined by Raman spectroscopy (Tab. 1).

The late Famennian of the Jebel El Mrakib, Jebel Krabis and Lambidia region (Aguelmous syncline; Becker et al. 2018) has stratigraphic intervals rich in Cymaclymenia (Klein & Korn 2014). Claystones, marls and thin nodular limestones characterized these intervals. These nodules and their fossil content usually carry a dessert varnish giving them a shiny surface. We analysed one specimen each from the Rich Chouiref and Jebel El Krabis, both of calcitic composition.

In the Visean concretion containing the ammonoid Entogonites (C10), quartz and calcite occur. Other Tournaisian and Visean goniatites collected in proximity of Erg Chebbi are comparable in their quartz and calcite composition (Tab. 1, 2). The inner whorls of the phragmocone of goniatites from the Visean of the southeastern Tafi lalt (Fig. 2I) and other faunas are preserved in baryte. This preservation is also known from roughly coeval strata of the Rhenish Massif (Germany: Korn 1988) and some Jurassic sites (Blum 1843; Wenk 1967).

The highly abundant thylacocephalans from the Famennian Thylacocephalan Layer of Madene El Mrakib (Fig. 3) have a hydroxypatite composition in the greyish to bluish remains of the carapace, while the sparitic fi lling of the carapace is calcitic. The surrounding concretions are occasionally greenish, where they consist of calcite. The reddish concretions are rich in haematite.

Vertebrates

Since actinopterygians and sarcopterygians play a subordinate role in the Famennian faunas of the eastern Anti-Atlas, we analysed the mineral content of remains of chondrichthyans and placoderms (Table 1, 2, Fig. 3, 4), both of which occur abundantly in some Late Devonian strata (Lehman 1956, 1964, 1976, 1977; Frey et al. 2018).

68

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

The vertebrate remains are usually contained in nodules of varying colours suggesting a carbonatic or iron-rich composition, respectively. Mineral analyses of greyish to greenish nodules contain calcite and perhaps siderite matching with presumed carbonatic composition (Tab. 1, 2). Several nodules with chondrichthyan or thylacocephalan remains share an orange, red to yellowish colour. Composed of calcite, haematite (causing the colour), and goethite (and possibly other hydroxides).

Hydroxyapatite is measured as expected in placoderm bones, chondrichthyan cartilage, teeth and in the thylacocephalan carapaces (Tab. 1, 2). The cartilaginous branchial arches of a small chondrichthyan are preserved in hydroxyapatite and calcite, while in the body, there is mainly calcite, perhaps combined with siderite and

subordinate haematite. Anterior to the pelvic girdle a pyrite nodule is preserved with the characteristic cubic crystals, surrounded by a crust of iron minerals (haematite, goethite).

Palaeogeography and facies

Palaeogeography

The palaeogeographical setting of the eastern Anti-Atlas was published in a series of articles (for more details, see Wendt 1985, 1988; Wendt and Belka 1991; Kaufmann 1998; Klug and Korn 2002). The interpretation of a homocline carbonate ramp in the Early Devonian that disintegrated and developed into three small epicontinental marine basins during the Middle Devonian in the eastern

Tab. 3. Characterization of marine Konservatlagerstätten based on the “questionnaire” of Seilacher et al. (1985). Character coding is explained in the material and methods chapter (where only 0 and 1 is coded, 0 means absence and 1 means presence).

69

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Anti-Atlas is widely accepted (Fig. 5). For the Late Devonian a nearly rectangular western basin, the so-called Maïder Basin is described. It has a width (E-W) of about 70 km in longitude and a length (N-S) of about 80 km in latitude. Hiatuses spanning the Devonian or more refl ect the approximate limits of the basin to the south and north. In the west, outcrops of Devonian sediments represent a strongly reduced thickness, thus documenting

the presence of the Maïder Platform. Eastern areas are covered and therefore lack outcrops of Devonian sediments. Further east series of E-W trending synclines with exposures of more or less strongly condensed carbonatic sediments in the Eifelian and Famennian. Wendt (1985, 1988) and Kaufmann (1998) suggested that these sediments were laid down in a continuously submerged area of reduced water depth, the Tafi lalt Platform.

70

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Probably, this palaeogeographic setting reduced the water exchange with the surrounding basins and the open ocean towards the north. Additionally, there are indications for a water depth exceeding 200 metres in the Maïder Basin: In the Givetian, a large reef mound formed on the southern slope of the basin (Kaufmann 1998). This mound was about 200 to 300 m high (Kaufmann 1998, Tessitore et al. 2016). It is unknown, how much sediment accumulated around the mound during the time of its growth, but it is well conceivable that the water depth was around 200 m, because indications for subaerial exposure are missing and the mound slopes appear rather steep today. With the cessation of mound growth, sea-level was rising, as suggested by the very thick overlying sequence of clayey sediments of late Givetian to middle Famennian age. Consequently, the water was possibly over 200, maybe 300 or even 400 metres deep in the depocentre (Tessitore et al. 2016). It is thus well conceivable that, during the Middle and Late Devonian, water exchange was low between the Tafi lalt Basin in the East and the very distant Tindouf Basin in the Southwest and the Maïder Basin, especially with the deeper parts of the Maïder Basin.

Facies

In the eastern Anti-Atlas, the Devonian succession starts with a thick sequence of clayey sediments, usually poor in fossils of benthic organisms and dark in colour. This suggests anoxic to hypoxic conditions during most of the Lochkovian (Belka et al. 1999; Dopieralska et al. 2006; Frey et al. 2014). Pragian sediments contain more carbonate and marls as well as marly limestones. Some of these layers contain rich benthonic as well as planktonic assemblages, indicating increased oxygen levels (Frey et al. 2014; Klug

et al. 2018). At the onset of the Emsian, nodular marls occur in the Tafi lalt, followed by fi ne claystones (weathering to a greenish scree) that yielded the largely haematitic Faunule 1 (Klug et al. 2008). During a short regression, the Deiroceras Limestone (Kröger 2008) was laid down; these carbonates commonly form a 50 to 100 cm thick limestone bed that can be easily recognized in the Tafi lalt. This dacryoconarid wackestone to packstone contains abundant large nautiloids of the genus Deiroceras, hence the name (see also Pohle and Klug 2018). Above, claystones follow that contain the predominantly haematitic Faunule 2 (Klug et al. 2008; De Baets et al. 2010); this sedimentary unit was dubbed Metabactrites-Erbenoceras Shale by Becker and Aboussalam (2011; see also Aboussalam et al. 2015). The Erbenoceras Limestone (Klug 2001; = Anetoceras Limestone of Bultynck and Walliser 2000; see also De Baets et al. 2010) varies in thickness and facies. In the northern Maïder, the Erbenoceras Limestone consists of an over 40 m thick sequence of moderately thin-bedded mudstones and wackestones (Döring 2002). At Jebel Mdouar (= Gara Mdouara, Klug 2017), the Erbenoceras Limestone (Units D and E of Klug 2001) is only 5 m thick and three fossiliferous massive limestone beds (mostly dacryoconarid packstones, sometimes with great amounts of crinoids; Klug 2001), each about one meter thick, dominate the sequence. The Daleje Shales were laid down during a global transgression (Haq and Schutter 2008); their carbonate content is usually low and thickness varies between over 160 m southeast of Tazoulait in the Maïder Basin and less than 40 m at the northern and southern limits of the basin (Döring 2002).

Both thickness and facies variation increase throughout the Devonian (Hollard 1974; Wendt 1985; Kaufmann 1998; Döring and Kazmierczak

↑ Fig. 2. Ammonoids from the eastern Anti-Atlas in different modes of preservation. Scale bar (1 cm) applies to all materials except H (ruler with millimetre scale at the bottom right). A to G, Cymaclymenia spp., Famennian, Maïder. A, PIMUZ 36863, pyritic internal mould, found in a depth of ca. 10 m in a well near Tafraoute (analysis in Tab. 1, Fig. 4). B, C, PIMUZ 36864 and PIMUZ 36865, surface collected specimens, pyrite entirely replaced by goethite with some iron hydroxides. D, PIMUZ 36866, calcium carbonatic internal mould with collapsed body chamber; Lambidia. E, PIMUZ 36867, calcium carbonatic specimen with replacement shell (also calcite) showing growth lines, Lambidia. F, PIMUZ 36868, calcium carbonatic internal mould with dessert varnish, Chouiref (analysis in Tab. 1, Fig. 4). G, PIMUZ 36869, calcium carbonatic internal mould with growth lines on replacement shell and collapsed phragmocone. H, Postclymenia evoluta, PIMUZ 31561, Hangenberg Black Shale, Madene El Mrakib; fl attened internal mould preserving fi ne shell structures (wrinkle layer, sutures, growth lines) and carbonatic remains of the formerly chitinous lower jaw (also fi gured in Klug et al. 2016, fi g. 3I). I, Neogoniatites delicatus, GPIT 1851-101, Viséan-Namurian boundary, E of Taouz; baritic internal mould of the phragmocone. J, typical surface-collected Famennian ammonoids, mostly goethitic internal moulds, Filon Douze. K, Gonioclymenia cf. inornata, PIMUZ 36870, Famennian, Madene El Mrakib; external mould of the umbilicus with collapsed replacement shell and internal mould of the thick dorsal siphuncle. L, Sobolewia nuciformis, GPIT 1871-245, Eifelian, Richt Tamirant; dolomitized internal mould (also fi gured in Klug 2002, pl. 13, fi g. 5). M, Ponticeras kayseri, GPIT 1849-388, late Givetian, Ouidane Chebbi (also fi gured in Belka et al. 1999, pl. 4, fi g. 12); chambers fi lled by white sparitic calcite, septa replaced by black calcite.

71

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

2001; Döring 2002; Lubeseder et al. 2010). The maximum thickness of the Middle Devonian sedimentary succession in this small basin can be found east of Tazoulait and reaches over 700 m (Fig. 1; Döring and Kazmierczak 2001). The corresponding sequence in the Tafi lalt is much thinner and varies mostly between 30 m on the Tafi lalt Platform (e.g., at Bou Tchrafi ne, Hamar Laghdad or Filon Douze) and over 220 m at Ottara, which was probably situated on the slope

towards the Maïder Basin (Kaufmann 1998; Lubeseder et al. 2010). Throughout most of the eastern Anti-Atlas, the Middle Devonian sequence is dominated by limestone, marl and claystone alternations. The closer to the depocentre in the Maïder Basin, the greater gets the proportion of mudstones and the thicker the argillaceous proportion of the sequences (Kaufmann 1998; Lubeseder et al. 2010). On the Tafi lalt Platform, condensed sedimentation prevailed; cephalopod

Fig. 3. XRD-spectra of various fossils from the eastern Anti-Atlas. For additional results see Tab. 1. Samples kept with the number PIMUZ 36879.

72

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

limestones (dacryoconarid wackestones and packstones) are common and macrofossils occur in great numbers (Wendt 1988; Kaufmann 1998; Döring and Kazmierczak 2001). In the late Givetian, the clay content increases and thick claystone sequences were laid down particularly in the southern Maïder Basin while on the Tafi lalt Platform, sometimes carbonate sedimentation continued into the Frasnian (e.g., Ouidane Chebbi: Belka et al. 1999).

During the Late Devonian, synsedimentary tectonics intensifi ed in the eastern Anti-Atlas,

which is refl ected in extreme differences in facies and thickness (Hollard 1974; Wendt 1985, 1988; Wendt and Belka 1991; Belka et al. 1999). In the Maïder and Tafi lalt Basins, sedimentation was dominated by claystones with sideritic and a few carbonatic levels (often nodular such as the Thylacocephalan Layer). Simultaneously, cephalopod limestones, sandy limestones and thick-bedded crinoid or cephalopod limestones (wackestones and packstones) were laid down on the Tafi lalt Platform (Wendt 1985). The terminal Devonian sedimentary sequence of the

Fig. 4. Raman-spectra of Devonian invertebrates and vertebrates from the eastern Anti-Atlas. For additional results see Tab. 1. A, Cymaclymenia sp., PIMUZ 36863, Tafraoute. B, Cymaclymenia sp., PIMUZ 36868, Chouiref. C, Maxigoniatites sp., PIMUZ 36871, 12 km S of Dar Kaoua. D, Thylacocephala gen. et sp. indet., PIMUZ 36873, Madene El Mrakib. E, F, large chondrichthyan, PIMUZ 36881, Madene El Mrakib. G, arthrodire, PIMUZ 36877, Ouidane Chebbi. H, small chondrichthyan, PIMUZ XX, Madene El Mrakib.

73

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Hangenberg Black Shale is composed of fi ne-grained clastics in most sections (Kaiser et al. 2011; Klug et al. 2016). In the southern Tafi lalt, the correlate of the Hangenberg Sandstone is rather fi ne-grained and between 3 m and 28 m thick, while in the Maïder, the 5 m to 15 m thick massive sandstone beds form a high cliff in most of the region (Kaiser et al. 2011). The Hangenberg Sandstone is overlain by a several hundred meter thick clastic sequence of fi ne-grained sandstones, siltstones and claystones (latest Famennian to Viséan) with abundant trace fossils, occasional plant remains and very few thin shell beds (Kaiser et al. 2011), some containing ammonoids (e.g., Korn et al. 1999, 2002; Klug et al. 2006) and other

shelled fauna (benthic, nektonic and planktonic). Occasional wave ripples document rather shallow water.

Palaeoecology

In spite of the proximity of the Maïder and the Tafi lalt Basins, ecological differences are evident not only from sediment thickness and facies (Massa 1965; Hollard 1974; Kaufmann 1998) but also from the faunal composition of coeval strata, especially in the Middle and Late Devonian. Regional palaeoecology was examined by Frey et al. (2014, 2018) for the Early Devonian of the

Fig. 5. Geologic map of the eastern Anti-Atlas showing the supposed outlines of the Maïder and Tafi lalt Basins as well as the Tafi lalt Platform in the Late Devonian (modifi ed after Wendt & Belka 1991). We indicated the occurrences of cephalopod-bearing Konzentrat-Lagerstätten as well as of gnathostome-bearing Konservat-Lagerstätten. Note that the indicated Konzentrat-Lagerstätten represent only some examples of a much greater number of such Lagerstätten. The various shades of blue suggest differences in water depth in the Late Devonian with darker blue indicating greater depth.

74

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

southern Tafi lalt and the Famennian to Tournaisian and locally for the Pragian to Eifelian by Klug et al. (2018). The differences in palaeoecological dynamic shifts through the Devonian in the two basins refl ects the special position and palaeo-environment of the Maïder Basin and is required for the explanation of the Famennian Konservat-Lagerstätten in the southern Maïder.

Lochkovian and Pragian

In the Lochkovian of Tafi lalt and Maïder, fossiliferous layers are rare and usually dominated by remains of nektonic to planktonic organisms like cephalopods with orthoconic conchs and graptolites (Frey et al. 2014). In the Maïder, the Lochkovian is not so well exposed because its sediments are mostly argillaceous with little carbonate. The high clay-content indicates moderately deep water with low oxygen conditions near the sediment surface.

Towards the top of the Lochkovian sequence, the carbonate content rises, fossils become more abundant and some bivalves as well as gastropods are present. This suggests an increasing oxygenation of the water column during the Pragian and early Emsian (as refl ected by high invertebrate diversities in the Tafi lalt and highly diverse trilobite faunas in the Maïder; Morzadec 2001; Frey et al. 2014; Klug et al. 2018). The increasing oxygenation eventually reached the top centimetres of the sediment (refl ected in occurrences of trace fossils: e.g., Klug & Hoffmann 2018), possibly in correlation with a reduced water depth. Vertebrate remains are rare in the Lochkovian and Pragian; some pectoral fi n spines of Machaeracanthus are found (Frey et al. 2014).

Emsian

Oxygen content continued to fl uctuate in the Emsian of the eastern Anti-Atlas, probably controlled by sea-level to some extent (Klug et al. 2008; De Baets et al. 2010; Frey et al. 2014; Aboussalam et al. 2015; Klug et al. 2018). Facies changes in the Tafi lalt and Maïder are rather uniform in the sense that changes from argillaceous to carbonate sedimentation occurred roughly synchronously in the Emsian (Massa 1965; Hollard 1974; Kaufmann 1998). In the Emsian sediments, geographical differences in facies, sediment thickness and fossil content are still low and correspondingly, the marine basins of the eastern Anti-Atlas did not change ecologically very much geographically. Although the oxygen content was likely varying, both benthic and non-benthic diversity stayed reasonably high until the end of the Zlíchovian (early Emsian; Massa 1965;

Frey et al. 2013, 2018). With the Daleje-transgression (basal Late

Emsian), overall diversity was reduced (but this might also be an effect of increased sediment accumulation rates) and benthics are much less abundant (Frey et al. 2014; Klug et al. 2018). Occasionally, trilobites, tabulate and rugose corals occur as well as small orthocerids and ammonoids, mostly preserved in goethite. It is well conceivable that the oxygen content of the lower part of the water column was low again linked to the transgression (Haq and Schutter 2008). During the latest Emsian, carbonate deposition resumed and diversity increased markedly including benthos (trilobites, gastropods, bivalves etc.), plankton (mostly dacryoconarids and orthocerids) and nekton (several ammonoid taxa, rare gnathostomes), refl ecting both a lower sea-level and improved sea-fl oor oxygenation (Frey et al. 2014; Klug et al. 2018). Particularly in the Maïder, late Emsian strata yielded several highly spinose trilobite taxa (e.g., Morzadec 2001; Chatterton and Gibb 2010).

The demersal acanthodian Machaeracanthus can locally be very abundant in the early Emsian (Klug et al. 2008; De Baets et al. 2010) and various placoderm taxa occur: remains of large arthrodires can be found in the late Zlíchovian (early Emsian) and the Dalejan (late Emsian) yielded remains of Atlantidosteus hollardi and Antineosteus lehmani in various localities of the Tafi lalt (Klug et al. 2008; Lelièvre 1984, 1995; Lelièvre et al. 1993, Rücklin and Clément 2017 ; Rücklin et al. 2018). The wealth of –sometimes large- invertebrate prey organisms represented the trophic base to sustain such large predators, which reached body lengths exceeding one meter.

Eifelian and Givetian

At the beginning of the Eifelian, the carbonate production increased further and some massive limestone beds were deposited, interrupted only by the Choteč-transgression. On the Tafi lalt Platform, the carbonates overlying the dark sediments of this transgression show many indications for condensed sedimentation such as eroded fossils, iron oxide-stained layers, high abundance of more or less fragmented mollusc conchs etc. The fauna is dominated by cephalopods (ammonoids, orthocerids, oncocerids, bactritids) and dacryoconarids, but bivalves (abundant), crinoids, trilobites, brachiopods and gastropods also occur. Overall, benthos plays a subordinate role, while nektonic and planktonic organisms are both diverse and abundant.

In the Maïder, carbonates prevail as well, but the sequences are much thicker and less fossiliferous (e.g., Jebel El Otfal, eastern Jebel El Mrakib,

75

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Jebel Issoumour), thus suggesting a greater water depth. Until the end of the Eifelian, the carbonate and fossil content fl uctuated gently (Massa 1965), likely refl ecting a mix of eustatic and regional sea-level changes (cf. Kaufmann 1998; Haq and Schutter 2008). Following the early Eifelian Choteč-Event and the late Eifelian Kačák-Event, the clay and organic content increased and locally, fossils are preserved in iron oxides.

On the Tafi lalt Platform, carbonate deposition lasted through the entire or at least parts of the Givetian. In the basal Givetian, ammonoids and other cephalopods occur in a moderate abundance and diversity. Especially in the northern Tafi lalt, the sometimes massive limestone beds are full of trace fossils, indicating a good oxygenation of the sea-fl oor. In the southern Tafi lalt, the early Givetian contains allochthonous sediments full of corals and brachiopods; these organisms possibly lived in somewhat shallower water.

From the Tafi lalt Platform towards the Tafi lalt and Maïder Basin, the Givetian sections become marly or clayey close to the base of the Frasnian. As far as invertebrate fossil preservation is concerned, it changes accordingly from carbonatic internal moulds (sometimes with calcitic shell; e.g., Bockwinkel et al. 2009) to goethite where the clay content reaches higher levels (e.g., at Hassi Nebech; Bensaïd 1974; Bockwinkel et al. 2013). Cephalopod diversity became rather high towards the end of the Givetian with tens of ammonoid species (Bockwinkel et al. 2015, 2017) as well as other cephalopods and only rare benthics. On the slope from the Tafi lalt to the Maïder Basin (Jebel Amessoui, Ottara), allochthonous layers rich in corals, stromatoporoids, crinoids and brachiopods alternate with argillaceous layers, yielding a more pelagic fauna. This documents an increase in water depth (Lubeseder et al. 2010).

The light grey Eifelian to early Givetian carbonates and claystones of the Maïder do yield occasional invertebrate remains such as corals, crinoids, brachiopods, trilobites, etc. Particularly at Jebel Rheris, Jebel Issoumour, Jebel Oufatene, Madene El Mrakib and around the reef-mound Aferdou El Mrakib, reef fauna occurs in more or less rock-forming amounts, sometimes in the form of biostromes or carbonate build-ups (Kaufmann 1998; Fröhlich 2006; Tessitore et al. 2013, 2016). Towards the end of the Givetian, carbonate production decreased and locally (particularly in the depocentre), ammonoid associations occur that show the same goethite-preservation as in the Tafi lalt Basin (Bockwinkel et al. 2015).

Machaeracanthus cf. peracutus continues into the Eifelian of Tafi lalt and Maïder, but it is less abundant than in the Emsian. From the Tafi lalt and Maïder, Lelièvre et al. (1993) and Rücklin and Clément (2017) further report the

placoderms Maideria falipoui Eastmanosteus sp. and Hollardosteus marocanus. Remains of large arthrodires possibly belonging to Eastmanosteus were found both in the strata following the Choteč- and Kačák-Events of Filon Douze and Ouidane Chebbi. Chondrichthyan teeth of Omalodus schultzei and Phoebodus fastigatus from the Givetian of the southern Tafi lalt Platform were also reported (Hampe et al. 2004; Kaufmann 1998). Additionally, the dipnoan Dipnotuberculus gnathodus was described from the Maïder (Campbell et al. 2002). In any case, this moderate diversity of vertebrate predators of varying size suggests that the invertebrate fauna provided enough prey organisms for these predators to thrive.

Frasnian

As mentioned above, lateral and vertical facies changes are more pronounced than during the Early and Middle Devonian. This suggests an increasing ecological differentiation of the region.

At the latest with the beginning of the Frasnian, argillaceous sedimentation began in most parts of the Tafi lalt Basin, the Maïder Basin and even on parts of the Tafi lalt Platform, refl ecting rising sea-levels (e.g., Wendt 1988; Kaufmann 1998; Lubeseder et al. 2010). At the same time, strongly condensed sedimentation happened in the Frasnian in the southwestern Maïder and on the northern Tafi lalt Platform (e.g., Wendt 1988; Wendt and Belka 1991; Hüneke 2006). Therefore, there was likely a stronger differentiation in both water depth and oxygen availability.

Frasnian to early Famennian sediments often display dark colours and have a high organic content with abundant iron-bearing minerals (‘Kellwasser Facies’ sensu Wendt and Belka 1991), refl ecting the high organic productivity on land (abundant wood fragments) and in the sea as well as the low oxygen of the lower water layers. This is corroborated by the facts that these sediments are rather poor in benthic fauna. In spite of the widespread low oxygen content, there still was enough oxygen for some organisms as documented in local trace fossil assemblages (e.g., Filon Douze; own fi eld data).

In the central Tafi lalt Platform, carbonate sedimentation persisted throughout much of the Late Devonian (Wendt 1985) and brachiopods, crinoids, bivalves, gastropods, as well as small rugose corals occur in a mostly low diversity and moderate to low abundance (own observations; compare, e.g., Massa 1965). The Kellwasser Limestone as well as some early and middle Famennian limestones can be very rich in fossils, but mostly cephalopods (occasionally, brachiopods, gastropods, bivalves, trilobites and

76

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

solitary corals also occur in low to moderate numbers).

Although the early Frasnian deposits are rather poor in vertebrates, the late Frasnian sediments yielded a rich vertebrate assemblage. For example, Rücklin and Clément (2017) listed the genera Enseosteus, Walterosteus, Rhinosteus, Draconichthys, Erromenosteus, Brachyosteus, Brachydeirus, Oxyosteus, Dinomylostoma, Holonema, and Aspidichthys. As far as chondrichthyans are concerned, Derycke (2017) reported fi n spines of Ctenacanthus sp.

In the southeastern of the Maïder Basin (Madene El Mrakib, Rich Bel Ras), the Kellwasser levels are represented by dark and massive cephalopod limestones (Wendt and Belka 1991). These sediments are rich in Archaeopteris-wood (Meyer-Berthaud et al. 1999), sometimes overgrown by holdfasts of some of the oldest pseudoplanktonic crinoids (Klug et al. 2003).

Famennian

Much of the Famennian succession is argillaceous in the Maïder and condensed carbonatic on the Tafi lalt Platform. In both regions, the Famennian is rich in diverse cephalopod associations (e.g., Korn and Bockwinkel 2017 and references therein); these fossils are preserved either in goethite or in carbonates (based on comparisons with our analysed samples; see Tab. 1). In combination with the mostly scarce benthic fauna, this suggests low oxygen levels of the bottom waters. In the middle and late Famennian of the Tafi lalt, limestones of locally strongly fl uctuating thickness occur, which also vary strongly in their fossil content (cephalopods, crinoids, brachiopods), documenting phases of moderate to good aeration in more or less shallow water conditions (e.g., Wendt et al. 1984; Wendt 1988).

Remarkably, the sediments of the Hangenberg Black Shale contain abundant ammonoids, occasionally orthocerids, small trace fossils, abundant bivalves and other fossils (Klug et al. 2016). The massive sandstones above indicate a regressive regime and likely were deposited during the end-Famennian regression (Kaiser et al. 2011; Becker et al. 2018). Palaeoecological changes throughout the Famennian and Tournaisian of the southern Maïder were studied by Frey et al. (2018).

Around the Devonian/ Carboniferous boundary, palaeobiodiversity is usually low. Some silt- and sandstone beds contain abundant brachiopods and there are also some layers rich in cephalopods. Starting from the latest Devonian into the Viséan, trace fossils can be diverse and abundant (Cruziana-like and Rusophycos-like traces, Diplichnites, Asteriacites etc.).

In spite of the great end-Frasnian mass extinction, which left its impressive traces also in Morocco (Buggisch 1991; Wendt and Belka 1991; Rücklin 2010, 2011), the Famennian vertebrate diversity is even higher than that of the Frasnian. Apparently, vertebrate assemblages recovered during the early Famennian. Accordingly, a great number of placoderm taxa were found in the Tafi lalt: Selenosteidae gen. et sp. indet., Dunkleosteus marsaisi, D. terrelli, Tafi lalichthys lavocati, Mylostomidae gen. et sp. indet., Titanichthys termieri and Alienacanthus sp. (Lehman 1956, 1964, 1967; Frey et al. 2018). Rücklin and Clément (2017) also report sarcopterygians of the families Actinistia and Tristichopteridae (Lehman 1977, 1978; Lelièvre and Janvier 1986). The number of chondrichthyan taxa is even more impressive. Derycke (1992, 2017) as well as Ginter et al. (2002) listed numerous taxa from the Tafi lalt.

In the Maïder, oxygen-depleted conditions recurred repeatedly in the lower part of the water column, which were not suited for such more demersal durophagous chondrichthyans to survive over a prolonged time. By contrast, chondrichthyans with grasping dentition such as the phoebodontids and cladodonts were probably living in the water column (Ginter et al. 2010) and thus, oxygen-poor conditions in the bottom water represented only a minor problem for them. Following Ginter (2000, 2001), we thus interpret the Maïder chondrichthyan assemblage as belonging to the “intermediate Phoebodus-Thrinacodus biofacies […] of moderately deep shelves”. In addition to the vertebrates listed above, we found skulls of onychodontids in the middle Famennian, which await their description. According to these published occurrences, the palaeobiodiversity of chondrichthyans surpassed that of placoderms following the Kellwasser Facies in the Tafi lalt.

Exceptional preservation and Fossil-Lagerstätten

Already in 1970, Seilacher coined the term “Fossil-Lagerstätte”, which is widely used today (Seilacher et al. 1985; Bottjer et al. 2002). He sub-classifi ed Fossil-Lagerstätten into Konservat-Lagerstätten and Konzentrat-Lagerstätten.

Konzentrat-Lagerstätten of the eastern Anti-Atlas

This kind of Fossil-Lagerstätte is characterized by a vast amount of specimens that do not necessarily have to be particularly well-preserved (e.g., Seilacher et al. 1985; Seilacher 1990; Bottjer et al. 2002). In the eastern Anti-Atlas, this kind of

77

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Fossil-Lagerstätte is quite common. Thus, it is impossible to provide a comprehensive list. We are focusing here on cephalopods, although there are also Konservat-Lagerstätten of, e.g., crinoids (e.g., Scyphocrinites/ Camarocrinus, Silurian/ Devonian boundary), brachiopods (e.g., Ivdelinia and Devonogypa, Middle Devonian), corals (e.g., Phillippsastrea, Middle Devonian), mixed benthic communities (e.g., Red Fauna; Klug et al. 2018) and other invertebrates in the eastern Anti-Atlas. Some conspicuous examples of cephalopod mass occurrences (Fig. 5, 6) are listed below:

1. Low diversity mass occurrences of the orthocerid Temperoceras ludense and other cephalopods in the late Silurian (Polygnathoides siluricus conodont Zone) and late Lochkovian (Kröger 2008);

2. High diversity cephalopod accumulations (Fidelites spp., Subanarcestes marhoumensis, Pinacites jugleri, Crispoceras spp., Lobobactrites sp., Oncocerida, Orthocerida) in the early Eifelian (Pinacites jugleri ammonoid Zone) of the southern Tafi lalt Platform (e.g., Filon Douze/ Jebel Ouaoufi lal; Klug 2002; Kröger 2008);

3. High diversity cephalopod accumulations (many species of Allopharciceras, Extropharciceras, Petteroceras, Pharciceras, Pseudoprobeloceras, Oxypharciceras, Sympharciceras, Tornoceras, Orthocerida, Oncocerida) in the late Givetian (e.g., Synpharciceras clavilobum ammonoid Zone) of the northern Tafi lalt Platform (Bockwinkel et al. 2009, 2017);

4. Moderate diversity cephalopod accumulations (several species of Archoceras Beloceras, Carinoceras, Crickites, Manticoceras, Tornoceratidae, Orthocerida, Oncocerida) occur in several layers, some of which associated with remains of arthrodires (upper Palmatolepis rhenana – Pa. linguiformis conodont Zones; Rücklin 2010, 2011) and Archaeopteris wood fragments in the Kellwasser Limestone of the Tafi lalt Platform and the southeastern Maïder (Wendt and Belka 1991);

5. Moderate diversity cephalopod accumulations (several species of Armatites, Cheiloceras, Falcitornoceras, Maeneceras, Paratorleyoceras, Polonoceras, Orthocerida, Oncocerida, Brachiopoda) in the early Famennian (Cheiloceras subpartitum to Paratorleyoceras globosum ammonoid Zones) of the Tafi lalt Platform and the southeastern Maïder (Becker 2002).

6. Low diversity cephalopod accumulations (several species of Platyclymenia, Prionoceras, Orthocerida) in the middle Famennian (Platyclymenia annulata Zone) of the Tafi lalt Platform and the southeastern Maïder region (Korn 1999). This stratigraphic interval often also yields placoderm remains of Dunkleosteus, in the Maïder even complete skeletons in huge nodules up to 4 m long (Lehman 1956, 1964, 1976).

7. Moderate diversity cephalopod accumulations (several species of Alpinites, Cymaclymenia, Cyrtoclymenia, Discoclymenia, Endosiphonites, Erfoudites, Falciclymenia, Gundolfi ceras, Mimimitoceras, Platyclymenia, Posttornoceras, Praeglyphioceras, Prionoceras, Orthocerida) of the late Famennian Clymenia Stufe (Gonioclymenia ammonoid genozone; e.g., Korn 1999). This interval contains also abundant microremains of chondrichthyans in the southern Tafi lalt (Ginter et al. 2002).

In the Middle Devonian, there are numerous localities with Konzentrat-Lagerstätten of more or less allochthonous reefal faunal assemblages; true reefs and biostromes are rare in the eastern Anti-Atlas (Fröhlich 2003). These moderate diversity accumulations of reef fauna may contain the following taxa: Phillipsastrea sp., Xystriphyllum sp., Heliophyllum halli moghrabiense, Cystiphylloides sp., Acanthophyllum sp., Thamnopora spp., auloporids, favositids, heliolitids, brachiopods, crinoids, stromatoporoids (e.g., Kaufmann 1998).

Konservat-Lagerstätten of the eastern Anti-Atlas

Also called conservation lagerstätten, these deposits received their name from their unusual preservation of animals or body parts that are normally not preserved (Seilacher 1970, 1990). The most famous Palaeozoic Konservat-Lagerstätte of Morocco occurs undoubtedly in the Fezouata Formation, which was compared to the classical Konservat-Lagerstätte of the Burgess Shale (van Roy et al. 2010). The term Konservat-Lagerstätte implies exceptional preservation of soft tissues, be they part of an organism with or without hard parts. The Devonian of Morocco is known for localities yielding articulated skeletons of various organisms such as trilobites, crinoids and also fi shes, but soft parts were not documented previously and thus, Konservat-Lagerstätten in a stricter sense were also unknown.

Recently, we described a fauna from the latest Famennian Hangenberg Black Shale of

78

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Fig. 6. Examples of Konzentrat-Lagerstätten (concentration lagerstätten) in the eastern Anti-Atlas. A, Mass occurrences of Temperoceras ludense and other cephalopods in the late Silurian, Ouidane Chebbi. Width about 1.5 m. B, High diversity cephalopod accumulation in the Eifelian of Filon Douze. C, Moderate diversity cephalopod accumulations (mainly Gephuroceratidae) in the Frasnian Kellwasser Limestone of Jebel Amelane. Width ca. 0.5 m. D, Moderate diversity reef fauna assemblage dominated by thamnoporids, Eifelian, Madene El Mrakib. E, F, Moderate diversity cephalopod accumulations (mainly cheiloceratids, orthocerids and brachiopods) in the early Famennian of Taouz (E) and Madene El Mrakib (F). G, H, Low diversity cephalopod accumulations (mainly Platyclymenia) in the middle Famennian (Platyclymenia annulata Zone) of Tachbit/ Mkarig (G) and Madene El Mrakib (H); width (in H) ca. 0.7 m.

79

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

the southern Maïder (Klug et al. 2016). These deposits yielded abundant non-mineralized cephalopod jaws, a few carbonized plant remains (algae), articulated arthropod remains lacking mineralized cuticles and also organic parts inside ammonoid body chambers that likely represent soft part remains. Accordingly, this deposit could be considered a Konservat-Lagerstätte because of articulated remains of skeletons and the preservation of abundant non-mineralized tissues.

Near the early to middle Famennian boundary (probably Palmatolepis rhomboidea or Pa. marginifera conodont Zone), we discovered a reddish argillaceous layer a few tens of centimeters thick and rich in iron oxides in the southern Maïder (Frey et al. 2018). This layer is characterized by abundant fl at nodules, mostly 50 to 100 mm in diameter and usually containing the carapaces and sometimes (primarily chitinous) appendages, eyes, gills, and possibly other organs (ongoing research) of thylacocephalans (Fig. 7, 8). This Thylacocephalan Layer (Frey et al. 2018) also yields articulated gnathostome remains, mostly of chondrichthyans, especially cladoselachian-like forms, symmoriids and phoebodontids as well as sarcopterygians and various arthrodires (Fig. 9, 10). Placoderms are commonly preserved in huge nodules, which likely refl ect the outline of the entire body (Fig. 9). As far as the chondrichthyans are concerned, we found remains of musculature, liver, digestive tract with prey remains, lateral lines, body outline, integument and cartilage (the latter being calcifi ed primarily, but still having a low preservation potential; Fig. 10). The preservation of such structures in articulated skeletons are classical characters of a Konservat-Lagerstätte (e.g., Seilacher et al. 1985).

Seilacher et al. (1985: fi g. 11) further refi ned the classifi cation of Konservat-Lagerstätten in a triangle (Fig. 12). Its corners are labelled ‘obrution’ (sedimentational régime; organic remains quickly

covered by sediment), ‘stagnation’ (hydrographic régime; organic remains preserved due to low oxygen levels) and ‘bacterial sealing’ (early diagenetic régime; bacterial fi lms replace or surround soft tissues, sometimes also fostering rapid phosphatisation; e.g., Kear et al. 1995).

The fossils of the Thylacocephalan Layer are preserved in a set of minerals including mainly hydroxyapatite, haematite, iron hydroxides, pyrite, siderite and quartz (Tab. 1). As discussed above, the iron oxides and hydroxides likely are products of slow weathering of primary pyrite in both the vertebrates and invertebrates (rarely, remains of which are preserved). This reduces the list of primary (now altered) minerals to phosphates and pyrite. Other Konservat-Lagerstätten with fossils preserved in pyrite and phosphates are the famous Early Devonian Hunsrück Slate and the Early Jurassic Posidonia Slate (Seilacher et al. 1985). Seilacher et al. (1985) somewhat arbitrarily placed these two Konservat-Lagerstätten in two different parts of the proposed ternary diagram of Konservat-Lagerstätten. While the Posidonia Slate is placed in the stagnation corner, the Hunsrück Slate (and also Solnhofen) are half way between the stagnation corner and the obrution corner, because post mortem transport and mass fl ows rapidly covering organic remains played an important role. In the case of Solnhofen, bacterial mats were also important, shifting its position towards the ‘bacterial sealing’ corner. Evidence for transport, obrution and bacterial mats have not been detected in the Devonian Thylacocephalan Layer. In combination with the facts that the Maïder Basin was a restricted basin with water exchange being limited by the Tafi lalt Platform and the scarcity of benthic organisms in the Thylacocephalan Layer, the Konservat-Lagerstätte of the Thylacocephalan Layer and other fossiliferous layers of the Famennian in that region are here assigned to

Fig. 7. The Thylacocephalan Layer (early middle Famennian) in the southern Maïder (Madene El Mrakib). A, thylacocephalan-bearing concretions in situ. B, surface accumulation of thylacocephalan-bearing nodules.

80

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Fig. 8. Phosphatic preservation of thylacocephalans from the Thylacocephalan Layer (early middle Famennian) in the southern Maïder (the orange-coloured sparitic fi lling is calcitic), PIMUZ 36872. A, lateral view of a carapace. B, broken specimen showing parts of the appendages preserved in apatite (Tab. 1).

Fig. 9. Preservation of gnathostomes from the Thylacocephalan Layer (early middle Famennian) in the southern Maïder. A, undescribed placoderm (? Driscollaspis sp.), PIMUZ 36882, Rich Bel Ras; note the preserved dorsal fi n and the caudal fi n (the concretion traced the body outline). B, cladoselachid chondrichthyan, PIMUZ 36883, Madene El Mrakib; preserved with several haematitic soft parts; note the ridge around the body that likely formed when the carcass sank into the mud ‒ the body itself collapsed later due to decay and sediment compaction, leaving a shallow depression.

81

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

the stagnation corner. Another shared character underlining the taphonomic similarity to the Posidonia Slate is the stratigraphically (much of the early and middle Famennian; Webster et al. 2005) and geographically widespread occurrence of pseudoplanktonic crinoids in the middle Famennian of both the Maïder and the southern Tafi lalt Platform (Klug et al. 2003; Webster et al. 2005; own unpublished fi eld data; Fig. 11).

In the attempt to classify marine Konservat-Lagerstätten in a more coherent way we use 31

characters predominantly based on Seilacher (1985). 19 well-known Konservat-Lagerstätten and the two herein described ones of the Devonian of Morocco were coded accordingly and analyzed in a Principal Component Analysis (Fig. 13). Remarkably, the Burgess-type Lagerstätten plotted in a fi eld well separated from the black shales and the Plattenkalke plotted again in a distinct fi eld. A black shale fi eld contains both Moroccan Konservat-Lagerstätten at opposite ends with the Thylacocephalan Layer being

Fig. 10. Soft-tissue preservation of a cladoselachid chondrichthyan, PIMUZ 36884, Thylacocephalan Layer (early middle Famennian), Madene El Mrakib (same specimen as in Fig. 12B. A, thoracal region directly anterior to the pelvic fi n with mineralized soft parts (muscles, neural arch cartilage, liver). B, detail of A showing muscle fi bres.

Fig. 11. Detail of a huge colony (1.10 m long with over 70 calyces) of the pseudoplanktonic crinoid Moroccocrinus ebbinghauseni from the late early Famennian of Jebel Ouaoufi lal. The Archaeopteris log is not preserved but was likely at the top of the image (note the difference in stem alignment on top and in the lower three quarters), running parallel to the hammer, and burying some of the crinoids below it. The colony was already excavated and is seen from below; on the other side, the degree of articulation is much lower.

82

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

close to La Voulte (which share the abundance of echinoderms, arthropods and ammonoids) and the Hangenberg Black Shale being close to Mazon Creek. This underlines the important role of low oxygen levels in the Maïder Basin during the Famennian, as proposed already by Frey et al. (2018).

Conclusions

We chemically analysed various Devonian and Early Carboniferous fossils from the eastern Anti-Atlas. Ammonoids and other cephalopods from this region and time interval are preserved in calcite, goethite (sometimes with haematite), quartz, baryte (only in the Early Carboniferous; Korn 1988), and clay minerals. As far as vertebrates and the thylacocephalansare concerned, we found the same minerals except baryte but with hydroxyapatite. In particular, the results show that the chondrichthyan musculature is now predominantly preserved in goethite and haematite. Both placoderm bones and chondrichthyan cartilage are preserved in apatite (mainly hydroxyapatite and probably also francolite). Especially the abundance of iron oxides and hydroxides suggest that some of these fossils were originally preserved in pyrite (at least partially), which was altered due to deep

weathering in the desert environment. This is corroborated by rare fi nds of completely pyritized fossils from the same strata in depths of over 10 m below today’s surface and by pyrite remains in the centre of some only partially oxidized fossils.

In turn, this primary abundance of pyrite (now goethite and iron hydroxides) in combination with the clayey facies and the scarcity of benthos in some strata suggest that the Thylacocephalan Layer containing exceptionally preserved gnathostomes was deposited under oxygen-poor conditions (Klug et al. 2016, Frey et al. 2018). This is supported by the palaeogeographical situation of the Maïder Basin (Fig. 4) that was closed to the south and north by land, while to the east and west, the shallower regions of the Tafi lalt Platform and the Maïder Platform limited water exchange (Wendt 1988; Kaufmann 1998).

Hypoxic to anoxic conditions in the bottom waters explain the absence of protacrodontids, which mainly occur in shallower, better oxygenated waters (Ginter 2000). Clairina and Jalodus likely preferred deeper environments than the one in the Maïder Basin. Following Ginter (2000), the taxa present in the Maïder (Phoebodus and cladodonts) point at an intermediate water depth.

Taking the exceptional fossil preservation (soft-tissue preservation), composition of the fossil assemblages (scarcity of benthos and demersal forms), the mineralogic composition of the fossils (primary pyrite, phosphates) and

Fig. 12. Ternary diagram of the three main types of conservation deposits of Seilacher et al. (1985). Some of the most famous examples are indicated by circles; note that the positions of the circles are somewhat arbitrary, partially because the respective roles of the main factors like, e.g., obrution and stagnation, change within these deposits and across the sedimentary basins. Also, there is no quantitative measure yet to place Lagerstätten within this diagram. In any case, obrution plays a much larger role in the famous Cambrian deposits compared to the Mesozoic black shales as well as the here portrayed Late Devonian Konservatlagerstätten from the eastern Anti-Atlas.

83

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

the palaeogeographic setting into account, the Famennian Thylacocephalan Layer is a Konservat-Lagerstätte. Since indications for mass movements, current alignment and traces of microbial activity sealing organismic remains have not been found, the Thylacocephalan Layer and the Hangenberg Black Shale are here considered as two examples of stagnation Lagerstätten sensu Seilacher et al. (1985) and thus the fi rst two of this kind from the Devonian of northern Africa (Fig. 12, 13). In our Principal Component Analysis of marine Konservat-Lagerstätten, these two Moroccan Lagerstätten plotted in the fi eld with of the black shales such as, e.g. the Triassic ones of Austria, Switzerland and China, the Jurassic ones of Europe etc. This new approach, based on the questionnaire by Seilacher et al. (1985), allows a more objective classifi cation of Konservat-Lagerstätten.

Acknowledgements. ‒ We greatly appreciate the support of the Swiss National Science Foundation for fi nancial support of our research projects (Project Numbers 200020_132870, 200020_149120, 200021_156105). We thank the colleagues of the Ministère de l’Energie, des Mines, de l’Eau et de l’Environnement (Direction du Développement Minier, Division du Patrimoine, Rabat, Morocco) who provided working and sample export permits. Saïd

Oukherbouch (Tafraoute) and René Kindlimann (Aathal, Switzerland) helped in the fi eld. Lydia Zehnder and Sebastian Cionoiu (both Earth Sciences Department, ETH Zürich) are thanked for their generous help with the XRD- and Raman-analyses. We acknowledge the constructive reviews of XX and XX.

References

Aboussalam, Z.S., Becker, R.T. & Bultynck, P. 2015: Emsian (Lower Devonian) conodont stratigraphy and correlation of the Anti-Atlas (Southern Morocco). Bulletin of Geosciences, 90(4), 893–980.

Arratia, G., Schultze, H.-P., Tischlinger, H. & Viohl, G. 2015: Solnhofen. Ein Fenster in die Jurazeit. Pfeil, München.

Becker, R.T. 2002: Stratigraphische Gliederung und Ammonoideen-Faunen im Nehdenium (Oberdevon II) von Europa und Nord-Afrika. Courier Forschungsinstitut Senckenberg, 155, 1–405.

Becker, R.T. & Aboussalam, Z.S. 2011: Emsian chronostratigraphy – preliminary new data and a review of the Tafi lalt (SE Morocco). SDS Newsletter, 26, 33–43.

Becker, R.T., Bockwinkel, J., Ebbighausen, V. & House, M.R., 2000. Jebel Mrakib, Anti-Atlas (Morocco), a potential Upper Famennian substage boundary stratotype section. Notes et Mémoires du Service géologique Maroc, 399, 75–86.

Becker, R. T., Hartenfels, S., Klug, C., Aboussalam,

Fig. 13. Principal Component Analysis of some marine Konservat-Lagerstätten. Classifi cation based on Tab. 3, which is based on the questionnaire by Seilacher et al. (1985). Note the perfect grouping of early Palaeozoic Burgess type Lagerstätten, Black Shale Lagerstätten and the Plattenkalke. Also note that the two Famennian Lagerstätten from Morocco plot at the limits of the Black Shale Lagerstätten.

84

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Z. S. & Afhüppe, L. 2018: The cephalopod-rich Famennian and Tournaisian of the Aguelmous Syncline (southern Maïder). Münstersche Forschungsberichte zur Geologie und Paläontologie, 110 (1): 273-306

Belka, Z., Klug, C., Kaufmann, B., Korn, D., Döring, S., Feist, R. & Wendt, J. 1999: Devonian conodont and ammonoid succession of the eastern Tafi lalt (Ouidane Chebbi section), Anti-Atlas, Morocco. Acta Geologica Polonica, 49 (1), 1–23.

Bensaïd, M. 1974 : Etude sur des Goniatites a la limite du Dévonien Moyen et Supérieur, du Sud Marocain. Notes de Service Carte géologique du Maroc, 36 (264), 81–140.

Berkowski, B. 2006 : Vent and mound rugose coral associations from the Middle Devonian of Hamar Laghdad (Anti-Atlas, Morocco). Geobios, 39, 155–170.

Blum, J.R. 1843: Die Pseudomorphosen des Mineralreichs. 378 pp., Schweizerbart, Stuttgart.

Bockwinkel, J., Becker, R.T. & Aboussalam, Z.S. 2017: Ammonoids from the late Givetian Taouzites Bed of Ouidane Chebbi (eastern Tafi lalt, SE Morocco). Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 284, 307–354.

Bockwinkel, J., Becker, R.T. & Ebbighausen, V. 2009: Upper Givetian ammonoids from Dar Kaoua (Tafi lalt, SE Anti-Atlas, Morocco). Berliner paläobiologische Abhandlungen, 10, 61–128.

Bockwinkel, J., Becker, R.T. & Ebbighausen, V. 2013: Late Givetian ammonoids from Hassi Nebech (Tafi lalt Basin, Anti-Atlas, southern Morocco). Fossil Record, 16, 5–65.

Bockwinkel, J., Becker, R.T. & Ebbighausen, V. 2015: Late Givetian ammonoids from Ait Ou Amar (northern Maider, Anti-Atlas, southeastern Morocco). Neues Jahrbuch für Geologie und Paläontologie, Abh., 278, 123–158.

Bottjer, D.J., Etter, W., Hagadorn, J.W. & Tang, C.M. (eds.) 2002: Exceptional Fossil Preservation. Columbia University Press, New York.

Buggisch, W. 1991: The global Frasnian-Famennian “Kellwasser Event”. Geologische Rundschau, 80, 49–72.

Campbell, K.S.W., Barwick, R.E., Chatterton, B.D.E. & Smithson, T.R.2002. A new Middle Devonian dipnoan from Morocco: structure and histology of the dental plates. Records of the Western Australian Museum, 21, 39–61.

Chatterton, B.D.E. & Gibb, S. 2010. Latest Early to Early Middle Devonian Trilobites from the Erbenochile Bed, Jbel Issoumour, Southeastern Morocco. Journal of Paleontology, 84, 1188–1205.

Clariond, L. 1935. Etude stratigraphique sur les terrains du Sud-Marocain. La série primaire du Sarhro, du Maider et du Tafi lalt. Publication Association Etudes géologiques du Méditerrané occidental, Géologie des Chaines nordafricaines, 5,1 (12), 3–10.

De Baets, K., Klug, C. & Monnet, C. 2013. Intraspecifi c variability through ontogeny in early ammonoids. Paleobiology, 39 (1), 75-94.

De Baets, K., Klug, C. & Plusquellec, Y. 2010. Zlíchovian faunas with early ammonoids from Morocco and their use for the correlation of the

eastern Anti-Atlas and the western Dra Valley. Bulletin of Geosciences, 85, 317–352. DOI 10.3140/bull.geosci.1172

Derycke, C., 1992. Microrestes de Sélaciens et autres Vertébrés du Dévonien supérieur du Maroc. Bulletin du Muséum national d’Histoire Naturelle, Section C, Sciences de la terre, paléontologie, géologie, minéralogie, 14 (1), 15–61.

Derycke, C., 2017. Paléobiodiversité des gnathostomes (chondrichthyens, acanthodiens et actinoptérygiens) du Dévonien du Maroc (NW Gondwana). In : Zouhri, S. (ed.), Paléontologie des vertébrés du Maroc : état des connaissances. Mémoires de la Société Géologique de France, 180, 47–78.

Derycke, C., Spalletta, C., Perri, M.C. & Corradini, C. 2008. Famennian chondrichthyan microremains from Morocco and Sardinia. Journal of Paleontology, 82, 984–995.

Dietl, G. & Schweigert, G. (2001). Im Reich der Meerengel. Pfeil Verlag, München.

Döring, S. 2002. Sedimentological evolution of the late Emsian to early Givetian carbonate ramp in the Mader (eastern Anti-Atlas, SE-Morocco). 121 pp. PhD-thesis, unpublishes, Tübingen. http://tobias-lib.ub.uni-tuebingen.de/volltexte/2002/560/

Döring, S. & Kazmierczak, M. 2001. Stratigraphy, geometry, and facies of a Middle Devonian ramp-to-basin transect (Eastern Anti-Atlas, SE Morocco). Facies, 44, 137–150.

Downs, R.T. & Hall-Wallace, M. (2003) The American Mineralogist Crystal Structure Database. American Mineralogist 88, 247-250.

Etter, W. 2002. Monte San Giorgio: Remarkable Triassic Marine Vertebrates. pp. 221–242.In: Bottjer, D. J., Etter, W., Hagadorn, J. W. & Tang C.M. (Eds.), Exceptional Fossil Preservation. 403 pp.Columbia University Press, New York.

Forey, P.L., Yi, L., Patterson, C. & Davies, C.E. (2003) Fossil fi shes from the Cenomanian (Upper Cretaceous) of Namoura, Lebanon. Journal of Systematic Palaeontology, 1: 227-330.

Frey, L., Naglik, C., Hofmann, R., Schemm-Gregory, M., Frýda, J., Kröger, B., Taylor, P.D., Wilson, M.A. & Klug, C. 2014. Diversity and palaeoecology of Early Devonian invertebrate associations in the Tafi lalt (Anti-Atlas, Morocco). Bulletin of Geoscience, 89(1), 75–112.

Frey, L., Rücklin, M., Korn, D. & Klug, C. 2018. Effects of Late Devonian mass extinctions on alpha diversity, ecospace occupation and vertebrate assemblages in south-eastern Morocco. Palaeogeography, Palaeoclimatology, Palaeoecology, 496, 1-17.

Fröhlich, S. 2003. Facies pattern and genesis of the Jebel Rheris biostromes (Givetian, Eastern Anti-Atlas, Morocco). Facies, 49, 209-220.

Ginter, M. 2000. Late Famennian pelagic shark assemblages. Acta Geologica Polonica, 50, 369–386.

Ginter, M. 2001. Chondrichthyan biofacies in the Late Famennian of Utah and Nevada, Journal of Vertebrate Paleontology, 21, 714-729.

Ginter, M., Hairapetian, V. & Klug, C. 2002. Famennian chondrichthyans from the shelves of North Gondwana. Acta Geologica Polonica, 52, 169–215.

85

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Grogan, E. D. & R. Lund. 2002. The geological and biological environment of the Bear Gulch Limestone (Mississippian of Montana, USA) and a model for its deposition. Geodiversitas, 24: 295-315.

Halamski, A. T. & Baliński, A., 2013. Middle Devonian brachiopods from the southern Maïder (eastern Anti-Atlas, Morocco). Annales Societatis Geologorum Poloniae, 83, 243–307.

Hammer, Ø., Harper, D.A.T. & Ryan, P.D. (2001): PAST: Palaeontological statistics software package for education and data analysis. Palaeontologia Electronica, 4(1): 1-9.

Hampe, O.Z., Aboussalam, Z.S. & Becker, R.T. 2004. Omalodus teeth (Elasmobranchii: Omalodontida) from the northern Gondwana margin (middle Givetian: ansatus conodont Zone, Morocco). In Arratia, G., Wilson, M.V.H. & Cloutier, R. (eds.): Recent Advances in the Origin and Early Radiation of Vertebrates, pp. 487-504, Verlag Dr. Friedrich Pfeil, München, Germany.

Haq, B.U. & Schutter, S.R. 2008: A chronology of Paleozoic sealevel changes. Science, 322, 64–68.

Hemleben, C. & Freels, D. 1977. Algen-laminierte und gradierte Plattenkalke in der Oberkreide Dalmatiens (Jugoslawien). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 154, 61-93.

Hollard, H. 1974: Recherches sur la stratigraphie des formations du Dévonien moyen, de l’Emsien supérieur au Frasnien, dans le Sud du Tafi lalt et dans le Ma’der (Anti-Atlas oriental, Maroc). Notes du Service Géologique du Maroc, 36, 7–68.

Hüneke, H. 2006 : Erosion and deposition from bottom currents during the Givetian and Frasnian: Response to intensifi ed oceanic circulation between Gondwana and Laurussia. Palaeogeography, Palaeoclimatology, Palaeoecology 234, 146–167

Kaiser, S.L., Becker, R.T., Steuber, T. & Aboussalam, Z.S. 2011. Climate-controlled mass extinctions, facies, and sea-level changes around the Devonian–Carboniferous boundary in the eastern Anti-Atlas (SE Morocco). Palaeogeography, Palaeoclimatology, Palaeoecology, 310, 340–364.

Kaufmann, B. 1998. Facies, stratigraphy and diagenesis of Middle Devonian reef- and mud-mounds in the Mader (eastern Anti-Atlas, Morocco). Acta Geologica Polonica, 48, 43–106.

Kear, A.J., Briggs, D.E.G. & Donovan, D.T. 1995. Decay and fossilization of non-mineralized tissue in coleoid cephalopods. Palaeontology, 38, 105–131.

Klein, C. & Korn, D. 2014. A morphometric approach to conch ontogeny of Cymaclymenia and related genera (Ammonoidea, Late Devonian). Fossil Record, 17, 1–32.

Klug, C. 2001. Early Emsian ammonoids from the eastern Anti-Atlas (Morocco) and their succession. Paläontologische Zeitschrift, 74 (4), 479–515.

Klug, C. 2002. Quantitative stratigraphy and taxonomy of late Emsian and Eifelian ammonoids of the eastern Anti-Atlas (Morocco). Courier Forschungsinstitut Senckenberg, 238, 1–109.

Klug, C. & Korn, D. 2002. Occulded umbilicus in the Pinacitinae (Devonian) and its palaeoecological implications. Palaeontology, 45, 917–931.

Klug, C. De Baets, K., Naglik, C. & Waters, J. 2014. New species of Tiaracrinus from the latest Emsian

of Morocco. Acta Palaeontologica Polonica, 59, 135–145.

Klug, C., Frey, L., Korn, D., Jattiot, R. & Rücklin, M. 2016. The oldest Gondwanan cephalopod mandibles (Hangenberg Black Shale, Late Devonian) and the Mid-Palaeozoic rise of jaws. Palaeontology, 59, 611–629.

Klug, C., Döring, S., Korn, D. & Ebbighausen, V. 2006. The Viséan sedimentary succession at the Gara el Itima (Anti-Atlas, Morocco) and its ammonoid faunas. Fossil Record, 9 (1), 3–60.

Klug, C. & Hoffmann, R. (2018): Trace fossils of Actiniaria (Conichnus) from the Early Devonian of Morocco. In: Klug, C. & Korn, D. (eds.): Palaeontology of the Devonian of Hamar Laghdad (Tafi lalt, Morocco). Special volume honouring JOBST WENDT. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 290 (1): 65-74.

Klug, C., Kröger, B., Rücklin, M., Korn, D., Schemm-Gregory, M., De Baets, K. & Mapes, R.H. 2008. Ecological change during the early Emsian (Devonian) in the Tafi lalt (Morocco), the origin of the Ammonoidea, and the fi rst African pyrgocystid edrioasteroids, machaerids, and phyllocarids. Palaeontographica A, 283, 83–176.

Klug, C. Samankassou, E., Pohle, A., De Baets, K., Franchi, F. & Korn, D. (2018): Oases of biodiversity: Early Devonian palaeoecology at Hamar Laghdad, Morocco. In: Klug, C. & Korn, D. (eds.): Palaeontology of the Devonian of Hamar Laghdad (Tafi lalt, Morocco). Special volume honouring Jobst Wendt. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 290 (1): 9-48

Klug, C., Schulz, H. & De Baets, K. 2009. Red trilobites with green eyes from the Early Devonian of the Tafi lalt (Morocco). Acta Palaeontologica Polonica, 54, 117–123.

Klug, C., Rücklin, M., Meyer-Berthaud, B. & Soria, A. 2003. Late Devonian pseudoplanktonic crinoids from Morocco. Neues Jahrbuch für Geologie und Mineralogie, 3, 153163.

Korn, D. 1988. Die Goniatiten des Kulmplattenkalkes (Cephalopoda, Ammonoidea; Unterkarbon; Rheinisches Schiefergebirge). Geologie und Paläontologie in Westfalen, 11, 1-293.

Korn, D. 1999. Famennian Ammonoid Stratigraphy of the Ma`der and Tafi lalt (Eastern Anti-Atlas, Morocco). Abhandlungen der geologischen Bundesanstalt, 54, 147179.

Korn, D. & Bockwinkel, J. 2017. The genus Gonioclymenia (Ammonoidea; Late Devonian) in the Anti-Atlas of Morocco. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 285, 97–115.

Korn, D., Bockwinkel, J. & Ebbighausen, V. 2007. Tournaisian and Viséan ammonoid stratigraphy in North Africa. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 243, 127–148.

Korn, D., Bockwinkel, J. & Ebbighausen, V. 2016a. The late Famennian tornoceratid ammonoids in the Anti-Atlas of Morocco. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 281(2), 201220.

Korn, D., Bockwinkel, J. & Ebbighausen, V. 2016b. Middle Famennian (Late Devonian) ammonoids

86

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

from the Anti-Atlas of Morocco. 3. Tornoceratids. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 281(3), 267281.

Korn, D., Klug, C. & Mapes, R.H. 1999. Viséan and Early Namurian Ammonoids from the Tafi lalt (Eastern Anti-Atlas, Morocco). Abhandlungen der Geologischen Bundesanstalt, Wien, 54, 345-375.

Korn, D., Klug, C., Ebbighausen, V. & Bockwinkel, J. 2002. Palaeogeographic meaning of a Middle Tournaisian ammonoid fauna from Morocco. Geologica et Palaeontologica, 36, 79-86.

Kröger, B. 2008. Nautiloids before and during the origin of ammonoids in a Siluro-Devonian section in the Tafi lalt, Anti-Atlas, Morocco. Special Papers in Palaeontology, 79, 1–112.

Kulczycki, J. 1957. Upper Devonian fi shes from the Holy Cross Mountains (Poland). Acta Palaeontologica Polonica, 2, 285395.

Laetsch, T. & Downs, R. (2006) Software for identifi cation and refi nement of cell parameters from powder diffraction data of minerals using the RRUFF Project and American Mineralogist Crystal Structure Databases. Abstracts from the 19th General Meeting of the International Mineralogical Association, Kobe, Japan.

Lehman, J.-P. 1956. Les Arthrodires du Dévonien supérieur du Tafi lalt (Sud Marocain). Notes et Mémoires du Service Géologique du Maroc, 129, 170.

Lehman, J.-P. 1964. A propos de quelques Arthrodires et Ichthyodorulites sahariens. Mémoire IFAN, 68, 193200.

Lehman, J.-P. 1976. Nouveaux poissons fossiles du Dévonien du Maroc. Annales de Paléontologie, Vertébrés 62, 134.

Lehman, J.-P. 1977. Sur la présence d�un Ostéolépiforme dans le Dévonien supérieur du Tafi lalt. Compte-Rendus de l�Académie des Sciences, 285D, 151153.

Lehman, J.-P. 1978. A propos de deux poissons du Famennien du Tafi lalet. Annales de Paléontologie, Vertébrés, 64, 143-152.

Lelièvre, H. 1984. Antineosteus lehmani n.g., n. sp., noveau brachythoraci du Dévonien inférieur du Maroc présaharien. Annales de Paléontologie, 70, 116-158.

Lelièvre, H. 1995. Description of Maideria falipoui n. g., n. sp., a long snouted brachythoracid (Vertebrata, Placodermi, Arthrodira) from the Givetian of Maider (South Morocco), with a phylogenetic analysis of primitive brachythoracids. Bulletin du Muséum National d�Histoire Naturelle, Paris, 4e série, C, 17, 163207.

Lelièvre, H. & Janvier, P. 1986. L�Eusthénopteridé (Osteichthyes, Sarcopterygii) du Famennian (Dévonien supérieur) du Tafi lalt (Maroc): nouvelle description. Bulletin du Muséum National d�Histoire naturelle, 4e Série, Section C, Sciences de la Terre, Paléontologie, Géologie, Minéralogie, 3, 351365.

Lelièvre, H. & Janvier, P. 1988. Un Actinistien (Sarcopterygii, Vertebrata) dans le Dévonien supérieur du Maroc. Compte-Rendus de l�Académie des Sciences, Paris, 307, 14251430.

Lelièvre, H., Janvier, P. & Blieck, A. 1993. Silurian-

Devonian vertebrate biostratigraphy of western Gondwana and related terranes (South America, Africa, Armorica-Bohemia, Middle East). In: Long, J.A. (ed.), Palaeozoic vertebrate biostratigraphy and biogeography. Belhaven Press , London, 139-173.

Lubeseder, S., Rath, J., Rücklin, M. & Messbacher, R. 2010. Controls on Devonian hemi-pelagic limestone deposition analyzed on cephalopod ridge to slope sections, Eastern Anti-Atlas, Morocco. Facies, 56, 295–315.

Massa, D. 1965. Observations sur les séries siluro-dévoniennes des confi ns algéro-marocains du Sud (1954-1955). Compagnie Française des Pétroles, Notes et Mémoires, 8, 1187.

Meyer-Berthaud, B., Scheckler, S.E. & Wendt, J. 1999. Archaeopteris is the earliest known modern tree. Nature, 398, 700701.

Morzadec, P. 2001. Les trilobites Asteropyginae du Dévonian de l�Anti-Atlas (Maroc). Palaeontographica A, 262, 53-85.

Pohle, A. & Klug, C. 2018: Body size of orthoconic cephalopods from the late Silurian and Devonian of the Anti-Atlas (Morocco). Lethaia, 51, 126-148.

Röhl, H. J., Schmid-Röhl, A., Oschmann, W., Frimmel, A. & Schwark, L. (2001).The Posidonia Shale (Lower Toarcian) of SW-Germany: An oxygen-depleted ecosystem controlled by sea level and palaeoclimate. Palaeogeography, Palaeoclimatology, Palaeoecology 165, 27–52

Röhl, A., Schmid-Röhl, H. J., Oschmann, W., Frimmel, A. & Schwark, L. (2002). Palaeoenvironmental reconstruction of Lower Toarcian epicontinental black shales (Posidonia Shale, SW Germany): Global versus regional control. Geobios 35, 13–20.

Rücklin, M. 2010. A new Frasnian placoderm assemblage from the eastern Anti-Atlas, Morocco, and its palaeobiogeographical implications. Palaeoworld, 19, 8793.

Rücklin, M. 2011. First selenosteid placoderms from the eastern Anti-Atlas of Morocco; osteology, phylogeny and palaeogeographical implications. Palaeontology, 54, 2562.

Rücklin, M. & Clément, G. 2017. Une révue des placodermes et sarcoptérygiens du Devonien du Maroc. In : Zouhri, S. (ed.), Paléontologie des vertébrés du Maroc: état des connaissances. Mémoires de la Société Géologique de France, 180, 79�102.

Rücklin, M., Lelièvre, H. & Klug, C. (2018): Placodermi from the Early Devonian Kess-Kess Mounds of Hamar Laghdad, Southern Morocco. In: Klug, C. & Korn, D. (eds.): Palaeontology of the Devonian of Hamar Laghdad (Tafi lalt, Morocco). Special volume honouring Jobst Wendt. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 290 (3): 301-306.

Rücklin, M., Long, J. A. & Trinajstic, K. 2015. A new selenosteid arthrodire (‘Placodermi’) from the Late Devonian of Morocco. Journal of Vertebrate Paleontology, 35(2), e908896, 113.

Seilacher, A. 1970. Begriff und Bedeutung der Fossil-Lagerstätten. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 1970, 34�39.

Seilacher, A. 1990. Taphonomy of Fossil-Lagerstätten. In Briggs, D.E.G. & Crowther, P.R. (eds),

87

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Palaeobiology: A synthesis. 266-270. Blackwell, Oxford.

Seilacher, A., Reif, W.-E. & Westphal, F. 1985. Sedimentological, ecological and temporal patterns of fossil Lagerstätten. Philosophical Transactions of the Royal Society of London B, 311, 5–23.

Termier, G. & Termier, H. 1950. Paléontologie Marocaine. II. Invertébrés de I’ère Primaire. Fascicule III. Mollusques. Service géologique, Protectorat de la République française au Maroc, Notes et Mémoires, 78, 1246.

Tessitore, L., Schemm-Gregory, M., Korn, D., Wild, F.R.W.P., Naglik, C. & Klug, C. 2013. Taphonomy and palaeoecology of the green pentamerid brachiopods from the Devonian of Aferdou el Mrakib, eastern Anti-Atlas, Morocco. Swiss Journal of Palaeontology, 132 (1), 23–44.

Tessitore, L., Naglik, C., De Baets, K., Galfetti, T. & Klug, C. 2016. Neptunian dykes in the Devonian carbonate buildup Aferdou El Mrakib (eastern Anti-Atlas, Morocco) and implications for its origin. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 281, 247-266.

Van Roy, P., Orr, P.J., Botting, J.P., Muir, L.A., Vinther, J., Lefebvre, B., el Hariri, K. & Briggs, D.E.G. 2010. Ordovician faunas of Burgess Shale type. Nature, 465, 215–218.

Webster, G.D., Becker, R.T. & Maples, C.G. 2005. Biostratigraphy, paleoecology, and taxonomy of

Devonian (Emsian and Famennian) crinoids from southeastern Morocco. Journal of Paleontology, 79, 1052–1071.

Wendt, J. 1985. Disintegration of the continental margin of northwestern Gondwana: Late Devonian of the eastern Anti-Atlas (Morocco). Geology, 13, 815–818.

Wendt, J. 1988. Facies pattern and palaeogeography of the Middle and Late Devonian in the eastern Anti-Atlas (Morocco). In: Mc Millan, N.J., Embry, A.F. & Glass, D.J. (Eds), Devonian of the World, I. Canadian Society of Petroleum Geologists, 467–480.

Wendt, J. Aigner, T. & Neugebauer, J. 1984. Cephalopod limestone deposition on a shallow pelagic ridge: the Tafi lalt-platform (Upper Devonian, eastern Anti-Atlas, Morocco). Sedimentology, 31, 601-625.

Wendt, J. & Belka, Z. 1991. Age and depositional environment of Upper Devonian (early Frasnian to early Famennian) black shales and limestones (Kellwasser facies) in the eastern Anti-Atlas, Morocco. Facies, 25, 51–90.

Wenk, R. 1967. Baryt und Ankerit aus Ammoniten des Berner Juras (Schweiz). Contributions to Mineralogy and Petrology, 14(2), 81–85.

Wilby, P. R., Duff, K., Page, K. & Martin, S. (2008). Preserving the unpreservable: a lost world rediscovered at Christian Malford, UK”, Geology Today 24.3: 95-98.

88

Chapter II: Fossil-Lagerstätten and Preservation of Fossils

Appendix I

Tab. 4. Tübingen questionnaires Fossil-Lagerstätten (after Seilacher et al. 1985).

CHAPTER III

Morphology, phylogenetic relationships and ecomorphology

of the early elasmobranch Phoebodus

Linda Frey, Michael Coates, Michal Ginter, Vachik Hairapetian, Martin Rücklin und Christian Klug

In preparation, formatted for Proceedings B

91

Chapter III: Phoebodontid Chondrichthyans of the Maider

Morphology, phylogenetic relationships and ecomorphology of the

early elasmobranch Phoebodus

Linda Frey1, Michael Coates2, Michał Ginter3, Vachik Hairapetian4, Martin Rücklin5, Iwan Jerjen6 and Christian Klug1

1Paläontologisches Institut und Museum, University of Zurich, Karl-Schmid-Strasse 4, CH-8006 Zürich (linda.frey@pim.uzh.ch; chklug@pim.uzh.ch) 2Department of Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th St., USA-60637 Chicago3Faculty of Geology, University of Warsaw, al. Żwirki i Wigury 93, PL-02-089 Warszawa4Department of Geology, Khorasgan Branch, Islamic Azad University, PO Box 81595-158, Esfahan, Iran5Naturalis Biodiversity Center, Postbus 9517, 2300 RA, Leiden, The Netherlands6Institute for Biomedical Engineering, ETH Zürich, Gloriastrasse 35, CH- 8092 Zürich

Although the anatomical knowledge of early chondrichthyans and thus their phylogeny is constantly im-proving, some taxa are still known only by microremains. Assumptions about the ecomorphology of the nearly cosmopolitan and regionally abundant Devonian chondrichthyan genus Phoebodus and the phy-logenetic relations to other phoebodontids were solely based on teeth and fi n spines. Here, we report the fi rst body remains and braincases of Phoebodus from the Famennian (Late Devonian) of the Maïder re-gion of Morocco. Phoebodus differs from other phoebodontids such as Thrinacodus in following features: an anguilliform but less slender body, a short otic process on the palatoquadrate, a derived shape of the ceratohyals and the presence of two dorsal fi n spines. Our phylogenetic analyses confi rm phoebodontids (Phoebodus and Thrinacodus) as stem elasmobranchs (crown Chondrichthyes). Phoebodontids form a polytomy together with Cladodoides, Tamiobatis, xenacanthids and hybodontids. They represent the earli-est anguilliform chondrichthyans in the fossil record and therefore underline the Devonian morphological disparity and ecological diversity of early gnathostomes.

Keywords: Gnathostomes, Chondrichthyes, neurocranium, homoplasy, Devonian, Morocco

1. Introduction

During the last decades, new records of ear-ly chondrichthyans ameliorated our anatomical knowledge of these jawed fi sh[1-15]. Although occasionally, articulated and complete skeletons of Palaeozoic chondrichthyans were discovered, some groups of early chondrichthyans are still exclusively known from microremains or mac-roscopic isolated hard parts such as teeth and fi n spines [16-18]. Accordingly, the skeletal anatomy of phoebodontids was entirely unknown until the discovery and description of Thrinacodus gra-cia [19] from the Serpukhovian locality of Bear Gulch, Montana. Thrinacodus gracia shows a highly derived body plan compared to other early chondrichthyans in having an extremely slender and elongate body as well as asymmetric tricus-pid teeth with a recurved crown [19-20]. Howev-er, complete crania or other skeletal remains of the common phoebodontid Phoebodus were un-known, even though their characteristic tricuspid

teeth (and tentatively, isolated fi n spines [Maisey in 18]) were recovered from numerous localities of Middle Devonian to Early Carboniferous age worldwide [18, 21-29].

Based on their abundant teeth, evolution-ary scenarios of members of the Phoebodontidae were postulated from symmetric teeth with broad bases (Ph. fastigatus [23], Ph. latus [24], Ph. bi-furcatus [23]) of Frasnian and earliest Famennian age to asymmetric tricuspid teeth with narrow bases of late Famennian age (Thrinacodus tran-quillus [30], Th. ferox [31]) [18]. The early/ mid-dle Famennian Phoebodus gothicus transitans already displays some asymmetry in base and crown and therefore, this species was inferred to represent a phylogenetic link between Phoebodus and Thrinacodus [26].

Here, we describe one nearly complete skel-eton and several three-dimensionally preserved skulls of Phoebodus that were discovered in the

92

Chapter III: Phoebodontid Chondrichthyans of the Maider

middle Famennian of the Maïder Basin of Moroc-co. We discuss the morphological similarities to the phoebodontid Thrinacodus gracia and its phy-logeny as well as ecology. We also discuss which impact the new morphological data of Phoebodus has on the ecomorphological diversity of Devoni-an chondrichthyans.

2. Material and methods

a) Specimens

The material includes visceral and postcranial re-mains of a skeleton of Phoebodus saidselachus sp. nov. (PIMUZ A/I 4712) as well as four three-di-mensionally preserved cranial remains (PIMUZ A/I 4656, 4710, 4711, 4713) that are housed at the Palaeontological Institute and Museum of the University of Zurich, Switzerland. Over the last decades, the material was collected from Madene El Mrakib, which is situated in the southern Maïder region of the eastern Anti-Atlas of Moroc-co (Fig. S1). The skeletal remains are preserved in ferruginous nodules of reddish colour found in the Thylacocephalan Layer (formerly described as Phyllocarid Layer; [32]) in which thylacoceph-alan arthropods are highly abundant. Dating of the host rocks by index ammonoids (Maeneceras horizon) suggest an early to middle Famennian age [33, 34].

(b) Anatomy inferred from CT-data

Computed tomograms of the three-dimensionally preserved skulls were acquired using a Nikon XT H 225 ST industrial CT-scanner at the University of Zurich, Switzerland. The braincase of PIMUZ A/I 4711 preserving parts of the otic and occiput yielded an image stack with good contrast be-tween matrix and fossil. Data acquisition and im-age reconstruction parameters: 221 kV, 349 mA; fi lter: 2 mm of copper; voxel sizes in mm: 0.0776 in each direction; the data was exported as a raw volume.

The volume was manually segmented and anatomical reconstructions were performed using the software Mimics v.17 (http://www.biomedi-cal.materialise.com/mimics; Materialise, Leuven, Belgium). Smoothing, colours and lighting were edited in MeshLab v. 2016 (http://www.meshlab.net; [35]) and blender v2.79b (https://www.blend-er.org; Amsterdam, Netherlands).

(c) Phylogenetic analyses

Our phylogenetic data matrix is based on those of Coates et al. [5] and Brazeau [36]. Data on ac-anthodian stem chondrichthyans are from Davis et al. [37] and Burrow et al. [38] while Zhu et al. [39] and Qiao et al. [40] provide data from the out-group. We updated the character matrix by adding character 58 (ceratohyal anteriorly blade-shaped) and by excluding 35 uninformative characters, which is the result of the adapted taxa list (22 taxa of stem gnathostomes were excluded; see supple-mentary material: chapter 3). The updated data matrix contains now 228 characters, 65 in-group taxa (including Phoebodus and Thrinacodus) and one out-group taxon (Entelognathus). Phyloge-netic analyses were performed in TNT 1.5 (Tree Analysis Using New Technology [41]) via heuris-tic parsimony analysis (traditional search in TNT) using 10000 multiple random addition sequences. Swapping algorithm is tree bisection reconnection (TBR) with 10 trees saved per replication. For the nodal support, we resampled the data using 1000 bootstrap replicants (standard bootstrap and tra-ditional search options in TNT 1.5) and we per-formed Bremer support retaining trees suboptimal by 5 steps (Fig. S9).

3. Results

a) Genus and species diagnosis and description

For some of the material (PIMUZA/I 4656, 4710, 4712), we introduce the species Phoebodus said-selachus sp. nov. because it combines characters of previously known microremains such as mul-ticuspid body scales (Fig. S8), ctenacanthid fi n spines (resembling Amelacanthus sp., Fig. S6; [16]) and teeth intermediate between Phoebodus typicus [24] and Phoebodus politus [42]. Two specimens (PIMUZ A/I 4711, 4713) were deter-mined as Phoebodus sp. because they preserve neither diagnostic teeth nor fi n spines. The new fossils yield important novel anatomical informa-tion about Phoebodus concerning body parts such as the mandibular and branchial arches, shoulder girdle and neural arches (Fig. 1). Additionally, computer tomographs revealed details of the otic and occipital regions of the braincase, endocast and brachial arches (Fig. 2-3, S5). Using this ad-ditional anatomical data, we emend the genus di-agnosis of Phoebodus (previously based on teeth only).

The current genus defi nition of Phoebodus

93

Chapter III: Phoebodontid Chondrichthyans of the Maider

Figure 1. Phoebodus saidselachus sp. nov., (a – d) PIMUZ A/I 4712, (e) PIMUZA/I 4656. (a) ferruginous nodule containing cranial and postcranial remains; (b) drawing, scale bar = 200 mm; (c) detail of visceral skeleton, scale bar 100 mm; (d) tooth, scale bar = 5 mm (e) tooth in labial, aboral, baso-lateral and linguo-basal views, scale bar = 10 mm. adbc: anterior dorsal basal cartilage; bh, basihyal; cb, ceratobranchial; ch, ceratohyal; col, cololite; fs, fi n spine; mc, Meckel`s cartilage; mpt, metapterygium; n, neurocranium; na, neural arches; pdbc: posterior dorsal basal carti-lage; pq, palatoquadrate; rad, radials; sc, scapulacoracoid.

based on teeth [18] is as follows: crown with three long main cusps equally sized or median cusps slightly shorter; sigmoid outline of main cusps; intermediate cusplets absent or present, if present then short and thin; base is symmetric, extending lingually, a single orolingual button on lingual to-rus for articulation with the overlying tooth, arcu-ate basolabial projection; two openings for basal canal: one aborally and one lingually.

With the new material of Phoebodus (notes in electronic supplementary material), the follow-ing characters are now added to the genus defi -nition: Skeleton consisting of tesselate calcifi ed

cartilage, jaws amphystylic with tooth fi les sep-arated by gaps, multicuspid trunk scales; pharyn-geal teeth present; otico-occipital fi ssure present, two dorsal fi n spines with ctenacanthid ornamen-tation; dorsal fi ns with calcifi ed base plate; high supraoccipital crest; dorsal otic ridge forming crests posteriorly; elongate endolymphatic fossa; occipital arch deeply wedged between otic cap-sule; massive hypotic lamina; external opening for endolymphatic ducts anterior to a crus com-mune; elongate and narrow body (eel-like shape) and mandibular arches; long occipital region, ap-proximately 75 % of the otic length; ceratohyal anteriorly blade-shaped; otic process of the pala-

94

Chapter III: Phoebodontid Chondrichthyans of the Maider

Figure 2. Otic and occipital region of Phoebodus saidselachus sp. nov., PIMUZ A/I 4711, reconstructed on the basis of CT-scans: (a) anterior; (b) ventral; (c) dorsal; (d) lateral; (e) posterior view. Braincase and articulated branchial arches: (f) ventral view of braincase and ceratohyals, (g) anterior aspect of ceratohyal, (h) lateral view of ceratohyal, (i) dorsolateral view on hyomandibula-braincase articulation. Scale bars = 30 mm. Abbreviations: chy, ceratohyal; dor, dorsal otic ridge; endf, endolymphatic foramen; esc, external semicircular canal; fm, foramen magnum; glc, glossopharyngeal canal; hl, hypotic lamina; hym, hyomandibula; lda, lateral dorsal aorta; lof, lateral otic fossa; nc, notochordal canal; oc cot, occipital condyle; occr, occipital crest; psc, posterior semicircular canal; sac, sacculum.

toquadrate is dorsoventrally short.

The dentition of Phoebodus appears to be ho-modont. However, most teeth are broken and the diagnostic tooth bases are usually poorly visible, hard to prepare or lack resolution in the CT-imag-ery (Fig. S2c, S3c, S7). Therefore, we could not

verify if only one or several tooth forms [e.g. 18, 26, 28-29] are present in the jaws. The homodonty has to be confi rmed with further fi ndings or higher resolved tomographies in the future.

95

Chapter III: Phoebodontid Chondrichthyans of the Maider

Figure 3. Otic and occipital region of the endocast of Phoebodus saidselachus sp. nov., (PIMUZ A/I 4711): (a) dorsal, (b) ventral, (c) lateral, (d) anterior and (e) posterior views. Scale bar = 30 mm. Abbreviations: esc, external semicircu-lar canal; med, medulla; pa, posterior ampulla; psc, posterior semicircular canal; sac, sacculum; socc, spino-occipital.

b) Phylogenetic analyses

Our phylogenetic analyses are based on a matrix with 228 characters, 65 ingroup taxa and one out-group taxon (Entelognathus), which resulted in 720 most parsimonious trees of 543 steps. The strict consensus tree places Phoebodus and Thri-nacodus on the elasmobranch branch of the chon-drichthyan group (Fig. 4). Both taxa form part of a polytomy together with Cladodoides and the Ta-miobatis-xenacanth (Diplodoselache, Triodus and Orthacanthus) branch.

4. Discussion

(a) Phylogenetic relationships

Based on dental characters, it is widely accepted that thrinacodontids derived from phoebodontids during the Famennian [e.g., 18, 26]. The skeletal material of Phoebodus described here corrobo-rates the close phylogenetic relationship to Thr-inacodus. Both taxa are characterised by elon-gate body morphologies with long and slender heads including elongated mandibles with teeth with three main cusps of similar size. However, as already suggested by tooth morphology, Thr-inacodus is indeed more derived in some cranial and postcranial characters than Phoebodus. Thr-inacodus has a lower body height; in Thrinaco-dus, the body is only 20 mm high (body height to length ratio c. 0.02) while in Phoebodus it is 140 mm high (body height to length ratio c. 0.13), i.e.

almost one order of magnitude higher in propor-tions. The dorsal fi ns as well as their fi n spines are completely reduced in Thrinacodus [19; Fig. 5]. They also differ in the shape of their palatoquad-rates; the quadrate region is higher in Thrinaco-dus and offers a larger attachment surface for the adductor muscles. In contrast to Thrinacodus, the palatoquadrate as well as Meckel`s cartilage are elongated in Phoebodus. More differences be-tween Thrinacodus and Phoebodus are present in their visceral skeletons. From Thrinacodus, hy-pohyals and a simple rod-shaped ceratohyal was described by Grogan and Lund [19: Fig. 10C]. Remarkably, the branchial skeleton of Phoebodus challenges previous interpretations of phoebodon-tid branchial anatomy: In Phoebodus, the derived blade-shaped ceratohyal articulates anteriorly directly to the basihyal and hypohals are absent (Fig. 1a, b, 2f-h). Due to the imperfect preserva-tion in Phoebodus, pectoral, pelvic and caudal fi ns cannot be compared adequately between the two phoebodontids and thus hamper the discussion of differences in locomotion and manoeuvrability.

Our phylogenetic analyses revealed that Phoebodus is a stem elasmobranch. In the clado-gram (strict consenus tree in Fig. 4), this genus is situated in a polytomy together with Clado-doides, Tamiobatis-xenacanthids branch and hy-bodontids. Phoebodus, Tamiobatis, Orthacanthus and Tristychius share characters in the braincase such as the elongated endolymphatic fossa later-ally fl anked by prominent dorsal otic ridges [Fig. 2a-e; 6, 43, 44]. Moreover, a prominent supraoc-cipital crest is a common feature in Phoebodus,

96

Chapter III: Phoebodontid Chondrichthyans of the Maider

Entelognathus

Youngolepis

Guiyu

Psarolepis

Cheirolepis

Mimipiscis

Raynerius

Moythomasia

Culmacanthus

Ischnacanthus

Nerepisacanthus

Poracanthodes

Tetanopsyrus

Uraniacanthus

Diplacanthus

Rhadinacanthus

Cassidiceps

Mesacanthus

Promesacanthus

Cheiracanthus

Acanthodes

Homalacanthus

Halimacanthodes

Gladbachus

Brachyacanthus

Brochoadmones

Climatius

Parexus

Ptomacanthus

V waynensis

Gyracanthides

Latviacanthus

Pucapampella

Kathemacanthus

Lupopsyrus

Obtusacanthus

Doliodus

Acronemus

Egertonodus

Hamiltonichthys

Onychoselache

Tribodus

Squalus

Synechodus

Tristychius

Homalodontus

Cladodoides

Phoebodus

Thrinacodus

Diplodoselache

Orthacanthus

Triodus

Tamiobatis

Dwykaselachus

Ozarcus

Cladoselache

Cobelodus

Akmonistion

Damocles

Falcatus

Debeerius

Chimaeroidei

Chondrenchelys

Helodus

Iniopera

Kawichthys

Fig

ure 4

. Cladogram

(strict consensus tree) showing the placem

ent of Phoebodus and T

hrinacodus within the elasm

obranchs. Colour coding: black, stem

group gnathostome (out-

group); green, Osteichthyes; red, A

canthodii (stem C

hondrichthyes); orange, stem C

hondrichthyes excluding Acanthodii; blue, E

lasmobranchii (crow

n Chondrichthyes); purple,

Holocephali (crow

n Chondrichthyes). W

hite circles: bootstrap support of knot > 50%

and/ or Brem

er decay values > 1; black circles: bootstrap support >

75% and/or B

remer decay

values > 3.

97

Chapter III: Phoebodontid Chondrichthyans of the Maider

Figure 5. Possible body reconstruction of (a) Phoebodus saidselachus sp. nov., Late Devonian, (b) Thrinacodus gracia (Grogan & Lund, 2008), Early Carboniferous, and (c) picture of Chlamydoselachus anguineus Garman, 1884, Recent.

Tristychius, and xenacanthids [Fig. 2a, e; 6, 44]. In both Tristychius and Phoebodus, the dorsal and occipital crests are arranged similarly relative to each other and the ceratohyal that anterolaterally expands forming a medially directed blade (Fig. 2g,h). However, the semicircular canals form a crus commune unlike in Tristychius, which indi-cates that Phoebodus did not have any phonore-ception. Moreover, the arrangement of the semi-circular canals and the massive hypotic lamina with two openings for the lateral aortae in com-bination with the large diameter of the occipital condyle are characters shared with Cladodoides and Orthacanthus [9,44]. Compared to other ear-ly groups of elasmobranchs, phoebodontid elas-mobranchs have a very elongate occipital region (Phoebodus: Fig. 1B, S4; Thrinacodus: see [19]:

?occipital elements in fi g. 10C, 12C). The low otic process on the palatoquadrate (Fig. 1c) separates Phoebodus from all other early elasmobranchs.

The phylogenetic results corroborate the pro-posed close relationship between phoebodontid and xenacanthid taxa based on tooth morphology [18,45]. However, more morphological data of phoebodontids is necessary to get a better reso-lution of the phylogenetic relationship between these two groups.

(b) Palaeoecology

The skeletal material of Phoebodus was found in the Maïder basin, which is a small epicontinental

98

Chapter III: Phoebodontid Chondrichthyans of the Maider

marine basin at the southern margin of the Palae-otethys [46-50]. Rough estimation of the palae-odepth of the Maïder basin suggested depths of maximally 400 meters in the depocentre and about 100 to 300 m at Madene el Mrakib [51]. Teeth of Phoebodus were mainly found in localities where moderately deep to moderately shallow water conditions prevailed during the Late Devonian; this taxon was proposed to live in the middle parts of the water column [18]. This coincides with the environmental conditions of the Maïder basin, where hypoxic to dysoxic conditions occurred repeatedly at the sea fl oor during the Famennian [32]; therefore, benthic life was rare and its diver-sity was correspondingly low in this region during much of the Famennian.

Among early chondrichthyans, phoebodon-tids are the fi rst taxa with an anguilliform body. Permian xenacanthid elasmobranchs also have a rather eel-like body but with several differences in anatomy [52-55]. Therefore, the discovery of skeletons of phoebodontids shows that the mor-phological disparity and ecological diversity of Devonian chondrichthyans was higher than pre-viously assumed.

The anguilliform body of phoebodontids is remarkably similar to that of the very distantly related modern neoselachian Chlamydoselachus. The length-to-height proportion of the body rather resembles Phoebodus, while dorsal fi n spines and dorsal fi ns are absent as in Thrinacodus except for a small second dorsal fi n in Chlamydoselachus. Because of these similarities in morphology and the absence of calcifi ed vertebrae centrae, we sug-gest that undulation was the mode of locomotion in phoebodontids (likely representing the plesio-morphic state of stem elasmobranchs).

The quadrate region of the palatoquadrate of both Phoebodus and Chlamydoselachus is dor-soventrally only slightly higher than the palatine ramus (Fig. 1a-c). Related to the function of the jaws, this implies that the surface for the attach-ment of the adductor muscle is reduced and that the bite was probably weaker than in other Palae-ozoic (e.g., xenacanthids, symmoriids) and mod-ern chondrichthyans.

Due to the similarities in body outline and tooth shape, Phoebodus probably pursued a feed-ing strategy comparable to chlamydoselachids al-though it is still unknown how the slow moving chlamydoselachids are capable of catching prey. Ram-feeding or lurking in combination with sud-denly snatching the prey are proposed feeding

behaviours [56, 57]. Because of the grasping den-tition of Phoebodus, they were unable to cut prey and only prey much smaller than their own body (which they could swallow whole) is feasible. Ad-ditionally, the morphology of the ceratohyal may inform about feeding mechanisms. Similarly to the ceratohyals of hybodontid Tristychius, those of Phoebodus are large and broad with a medial-ly directed anterior blade. Therefore, Phoebodus might have been a suction-feeder like hybodonts.

Stomach contents of phoebodontids were only found in Thrinacodus so far and they include remains of small chondrichthyans (Falcatus falca-tus [58], Harpagofututor volsellorhinus [59]) and crustaceans [19]. In recent frilled sharks, epipe-lagic squids, scyliorhinid and squaloid sharks [57, 60] were reported as stomach content. Possible prey for Phoebodus could have been thylacoceph-alan arthropods, which occur in great numbers in the host rocks of the Moroccan phoebodontids [32].

(c) Macroevolutionary implications

Based on the identifi cation of phoebodontids as stem elasmobranchs, an important macroevolu-tionary trend is emphasized. Generally, the Han-genberg Crisis is interpreted as a phase of a major turnover among vertebrates forming a bottleneck in their evolutionary history [61,62]. The pattern for Actinopterygii indicates a low diversity and disparity in the Devonian followed by an increase of morphological and taxonomic diversity after the Hangenberg Event [63]. Our new data about phoebodontids and thus the earliest anguiliform chondrichthyans emphasizes the morphological and taxonomic diversity of stem elasmobranchs during the Devonian. Remains of phoebodontids were reported from the Givetian (Middle Devo-nian; [18, 23]), which shows that stem elasmo-branchs were probably ecologically diverse long before the Hangenberg Event. This suggested disparate pattern for stem elasmobranchs and stem actinopterygians needs further analyses of the comparative anatomy of organ systems, their functional morphology and ecological interpreta-tion.

4. Conclusions

The fi rst anatomical information of the very com-mon genus Phoebodus based on the new species Ph. saidselachus sp. nov. in combination with the

99

Chapter III: Phoebodontid Chondrichthyans of the Maider

knowledge of Thrinacodus gracia revealed that phoebodontids are anguiliform chondrichthyans. Our phylogenetic analyses show that phoebodon-tids are good candidates as the earliest stem elas-mobranchs exhibiting elongate bodies. Including the fact that the oldest phoebodontid remains are of Givetian age, this indicates that the root of stem elasmobranch diversifi cation temporally took place far back in the evolutionary history of chondrichthyans.

Author contributions: C.K, M. R., M.C and L.F.: developing the project; C.K, M. R. and L.F: fi eld work; I. J.: acquisition of computer tomogra-phy scans; M.G and V. H. determination of tooth material; M.C. and L.F: interpretation of fossils and 3D-models; phylogenetic analysis. L.F. illus-trations, anatomical reconstruction, drafting man-uscript.

Competing interests: The authors declare no competing interests.

Funding: The project (project number S-74602-11-01) was fi nancially supported by the Swiss Na-tional Fond. . M.R. was supported by NWO (VIDI 864.14.009).

Data accessibility: In preparation.

Acknowledgments: We greatly appreciate the help of Saïd Oukherbouch (Tafraoute, Morocco) who supported us during fi eld work and discov-ered some of the main specimens. We acknowl-edge Ben Pabst (Aathal) and Christina Brühwiler (University of Zurich) for their excellent prepara-tion work. Moreover, we thank Anita Schweizer (Zurich), Alexandra Wegmann (University of Zu-rich) for the acquisition of CT-scans. Many thanks to Thodoris Argyriou (University of Zurich), To-bias Reich (University of Zurich) and Amane Ta-jika (NHM of New York) for CT-scanning and help with segmentation. Gabriel Aguirre kindly helped with the phylogenetic analyses. We thank René Kindlimann (Aathal) for the very fruitful discussions and inputs.

5. References

1. Zangerl R. 1981 Chondrichthyes I. In Paleozoic Elasmobranchii. Handbook of paleoichthyology 3A (ed. H-P Schultze), 115 p. New York, Gustave

FischerVerlag.2. Stahl BJ. 1999 Chondrichthyes III. In Holocephali.

Handbook of paleoichthyology 4 (ed. H-P Schult-ze), 164 p. München, Verlag Dr. Friedrich Pfeil.

3. Coates, M. I. and Sequeira, S. E. K. 2001. A new stethacanthid chondrichthyan from the Lower Car-boniferous of Bearsden, Scotland. J. Vert. Paleon-tol. 21(3), 438-459.

4. Coates MI, Finarelli JA, Sansom IJ, Andreev PS, Criswell KE, Tietjen K, Rivers ML, La Riviere PJ. 2018 An early chondrichthyan and the evolution-ary assembly of a shark body plan. Proc. R. Soc. Lond. Ser. B. Biol. Sci. 285: 20172418. (dx.doi.org/10.1098/rspb.2017.2418)

5. Coates MI, Gess RW, Finarelli JA, Criswell KE, Tiet-jen K. 2017 A symmoriiform chondrichthyan brain-case and the origin of chimaeroid fi shes. Nature, 541(7636), 208. (doi.org/10.1038/nature20806)

6. Coates MI, Tietjen K. 2018 The neurocranium of the Lower Carboniferous shark Tristychius arcua-tus (Agassiz, 1837). Earth Environ. Sci. Trans. R. Soc. Edinb. 108(1), 19-35. (doi.org/10.1017/S1755691018000130)

7. Maisey JG. 2001 A primitive chondrichthyan brain-case from the middle Devonian of Bolivia. In Ma-jor events in early vertebrate evolution (ed. PE Ahl-berg), pp. 263-288. London, UK: Taylor & Francis.

8. Maisey JG, Anderson ME. 2001 A primitive chon-drichthyan braincase from the Early Devonian of South Africa. J. Vert. Paleontol. 21, 702-713. (doi.org/10.1671/0272-4634(2001)021[0702:APCB-FT]2.0.CO;2)

9. Maisey JG. 2005 Braincase of the Upper Devonian shark Cladodoides wildungensis (Chondrichthyes, Elasmobranchii), with observations on the brain-case in early chondrichthyans. Bull. Am. Mus. Nat. Hist. 288, 1-103. (doi:10.1206/0003-0090(2005)288<0001:BOTUDS>2.0.CO;2)

10. Maisey JG. 2007 The braincase in Paleo-zoic symmoriiform and cladoselachian sharks. Bull. Am. Mus. Nat. Hist. 307, 1-122. (doi:10.1206/0003-0090(2007)307[1:TBIPSA]2.0.CO;2)

11. Maisey JG, Miller R, Turner S. 2009 The braincase of the chondrichthyan Doliodus from the Lower Devonian Campbellton Formation of New Bruns-wick, Canada. Acta Zool.-Stockholm Suppl. 90, 109-122. (doi:10.111/j.1463-6395.2008.00330.x)

12. Janvier P, Maisey JG. 2010 The Devonian verte-brates of South America and their biogeographical relationships. In Morphology, phylogeny and pale-obiogeography of fossil fi shes (eds DK Elliot, JG Maisey, X Yu, D Miao), pp. 431-459. München, Verlag, Dr. Freidrich Pfeil.

13. Pradel A. 2010 Skull and brain anatomy of Late Carboniferous Sibyrhynchidae (Chondrichthy-es, Iniopterygia) from Kansas and Oklahoma (USA). Geodiversitas 32, 595–566. (doi:10.5252/g2010n4a2)

100

Chapter III: Phoebodontid Chondrichthyans of the Maider

14. Pradel A, Tafforeau P, Maisey JG, Janvier P. 2011 A new Paleozoic Symmoriiformes (Chondrichthy-es) from the Late Carboniferous of Kansas (USA) and Cladistic Analysis of Early Chondrichthyans. PLoS ONE 6, e24938. (doi:10.1371/journal.pone.0024938)

15. Pradel A, Maisey JG, Tafforeau P, Mapes RH, Mallatt JA. 2014 A Palaeozoic shark with osteich-thyan-like branchial arches. Nature 509, 608-611. (doi:10.1038/nature13195)

16. Maisey JG. 1982 Studies on the Paleozoic selachian genus Ctenacanthus Agassiz. No. 2, Bythiacanthus St. John and Worthen, Amelacanthus, new genus, Eunemacanthus St. John and Worthen, Sphenacan-thus Agassiz, and Wodnika Münster. Am. Mus. No-vit. 2722.

17. Maisey JG. 1984 Studies on the Paleozoic sela-chian genus Ctenacanthus Agassiz. No. 3, Nominal species referred to Ctenacanthus. Am. Mus. Novit. 2774.

18. Ginter M, Hampe O, Duffi n, C J. 2010 Chondrich-thyes: Paleozoic Elasmobranchii: teeth. In Hand-book of paleoichthyology, 3D (ed. H-P Schultze), 168 p.

19. Grogan ED, Lund R. 2008 A basal elasmobranch, Thrinacoselache gracia n. gen & sp., (Thrinaco-dontidae, new family) from the Bear Gulch Lime-stone, Serpukhovian of Montana, USA. J. Vert. Pa-leontol. 28(4), 970-988.

20. Ginter M, Turner S. 2010 The middle Paleozoic Se-lachian genus Thrinacodus. Journal of Vertebrate Paleontology 30(6), 1666–1672, DOI:10.1080/02724634.2010.520785.

21. Long J A. 1990 Late Devonian chondrichthyans and other microvertebrate remains from northern Thailand. J. Vert. Paleontol. 10, 59-71.

22. Ginter M. 1990 Late Famennian shark teeth from the Holy Cross Mts, Central Poland. Acta Geol. Po-lon. 40, 69-81.

23. Ginter M, Ivanov A. 1992 Devonian phoebodont shark teeth. Acta Geol. Polon. 37(1), 55-75.

24. Ginter M, Ivanov A. 1995 Middle/Late Devonian Phoebodont-based ichthyolith zonation. [Zonation ichthyologique du Dévonien moyen/supérieur fon-dée sur les Phoebodontes]. Geobios 19, 351-355.

25. Ivanov A. 1995 Late Devonian vertebrate fauna of the South Urals. Geobios, 28, 357-359.

26. Ginter M, Hairapetian V, Klug C. 2002 Famennian chondrichthyans from the shelves of North Gond-wana. Acta Geol. Polon. 52 (2), 169-215.

27. Ginter M, Turner S. 1999 The early Famennian re-covery of phoebodont sharks. Acta Geol. Polon., 49(2), 105-117.

28. Hairapetian V, Ginter M. 2009 Famennian chon-drichthyan remains from the Chahriseh section, central Iran. Acta Geol. Polon. 59(2), 173-200.

29. Hairapetian V, Ginter M. 2010 Pelagic chondrich-thyan microremains from the Upper Devonian of the Kale Sardar section, eastern Iran. Acta Geol.

Polon. 60(3), 357-371.30. Ginter M. 2000 Late Famennian pelagic shark as-

semblages. Acta Geol. Polon. 50(2), 369-386. 31. Turner S. 1982 Middle Palaeozoic elasmobranch

remains from Australia. J. Vert. Paleontol. 2, 117-131.

32. Frey L, Rücklin M, Korn D, Klug C. 2018 Late Devonian and Early Carboniferous alpha diversity, ecospace occupation, vertebrate assemblages and bio-events of southeastern Morocco. Palaeogeogr. Palaeoclimatol. Palaeoecol. 496, 1-17.

33. Becker RT, House M R, Bockwinkel J, Ebbighau-sen V, Aboussalam ZS. 2002 Famennian ammonoid zones of the eastern Anti-Atlas (southern Moroc-co). Münster. Forsch. Geol. Paläont. 93, 159-205.

34. Korn D, Klug C. 2002 Fossilium Catalogus I: An-imalia Pars 138, Ammoneae Devonicae. Leiden, Netherlands, Backhuys Publishers.

35. Cignoni P, Callieri M, Corsini M, Dellepiane M, Ganovelli F, Ranzuglia G. 2008 MeshLab: an Open-Source Mesh Processing Tool. Sixth Euro-graphics Italian Chapter Conference, 129-136.

36. Brazeau MD. 2009 The braincase and jaws of a Devonian acanthodian and modern gnathostome origins. Nature 457, 305-308. (doi: 10.1038/na-ture07436)

37. Davis SP, Finarelli JA, Coates MI. 2012. Acanth-odes and shark-like conditions in the last common ancestor of modern gnathostomes. Nature 486, 247-250. (doi:10.1038/nature11080)

38. Burrow CJ, den Blaauwen J, Newman M, David-son R. 2016 The diplacanthid fi shes (Acanthodii, Diplacanthiformes, Diplacanthidae) from the Mid-dle Devonian of Scotland. Palaeontol. Electron. 19, 1-83.

39. Zhu M, Yu X, Ahlberg PE, Choo B, Lu J, Qiao QL, Zhao J, Blom H, Zhu Y. 2013 A Silurian placoderm with osteichthyan-like marginal jaw bones. Nature 502, 188-193. (doi:10.1038/nature12617)

40. Qiao T, King B, Long JA, Ahlberg PE, Zhu M. 2016 Early gnathostome phylogeny revisited: mul-tiple method consensus. PLoS ONE 11, e0163157. (doi:10.1371/journal.pone.0163157)

41. Goloboff PA, Catalano SA. 2016 TNT version 1.5, including a full implementation of phylogenetic morphometrics. Cladistics 32, 221-238.

42. Newberry JS. 1889 The Paleozoic fi shes of North America, Monograph of the U.S. Geological Sur-vey 16, 1-340.

43. Williams ME. 1998 A new specimen of Tamiobatis vetustus (Chondrichthyes, Ctenacanthoidea) from the Late Devonian Cleveland Shale of Ohio. J. Vert. Paleontol. 18(2), 251-260.

44. Schaeffer B. 1981 The xenacanths shark neurocra-nium, with comments on elasmobranch monophy-ly. Bull. Am. Mus. Nat. Hist.169, 1-66.

45. Ginter M. 2004 Devonian sharks and the origin of Xenacanthiformes. In Recent advances in the ori-gin and early radiation of vertebrates (eds. G Ar-

101

Chapter III: Phoebodontid Chondrichthyans of the Maider

ratia, MVH Wilson, R Cloutier). p. 473-486. Mün-chen, Friedrich Pfeil.

46. Wendt J. 1985 Disintegration of the continental margin of northwestern Gondwana: Late Devonian of the eastern Anti-Atlas (Morocco). Geology 13, 815-818.

47. Wendt J.1995 Shell directions as a tool in palae-ocurrent analysis. Sediment. Geol. 95, 161-186.

48. Wendt J, Kaufmann B, Belka Z, Klug C, Lubeseder S. 2006 Sedimentary evolution of a Palaeozoic ba-sin and ridge system: the Middle and Upper Devo-nian of the Ahnet and Mouydir (Algerian Sahara). Geol. Mag. 143(3), 269-299.

49. Fröhlich S. 2004 Evolution of a Devonian carbon-ate shelf at the northern margin of Gondwana (Jebel Rheris,eastern Anti-Atlas, Morocco). Unpublished PhD Thesis, University of Tübingen, Germany.

50. Lubeseder S, Rath J, Rücklin M, Messbacher R. 2010 Controls on Devonian hemi-pelagic lime-stone deposition analyzed on cephalopod ridge to slope sections, Eastern Anti-Atlas, Morocco. Fa-cies 56, 295-315.

51. Tessitore L, Naglik C, De Baets K, Galfetti T, and Klug C. 2016 Neptunian dykes in the Devonian carbonate buildup Aferdou El Mrakib (eastern An-ti-Atlas, Morocco) and implications for its growth. Neues Jahrb. Geol. Paläontol. Abhl. 281(3), 247-266.

52. Heidtke UHJ. 1982 Der Xenacanthide Orthacant-hus senckenbergianus aus dem pfälzischen Rotlie-genden (Unter-Perm). Pollichia 70, 65-86.

53. Heidtke UHJ. 1999 Orthacanthus (Lebachacant-hus) senckenbergianus Fritsch 1889 (Xenacanthi-da: Chondrichthyes): revision, organisation und phylogenie. Freiberger Forschungsheft 481, 63-106.

54. Heidtke UHJ, Schwind C. 2004 Über die Organisa-tion des Skelettes der Gattung Xenacanthus (Elas-mobranchii: Xenacanthida) aus dem Unterperm des südwestdeutschen Saar-Nahe-Beckens. Neues Jahrb. Geol. Paläontol. Abhl. 231(1), 85-117.

55. Heidtke UHJ, Schwind C, Krätschmer K. 2004 Über die Organisation des Skelettes und die ver-wandschaftlichen Beziehungen der Gattung Trio-dus Jordan 1849 (Elasmobranchii: Xenacanthida). Mainzer geowiss. Mitt. 32, 9-54.

56. Smith BG. 1937 The Anatomy of the Frilled Shark, Chlamydoselachus anguineus Garman. Bashford Dean Memorial Volume: Archaic Fishes Article 6, 333-506. American Museum of Natural History, N.Y.

57. Ebert DA, Compagno LJV. 2009 Chlamydosela-chus africana, a new species of frilled shark from southern Africa (Chondrichthyes, Hexanchiformes, Chlamydoselachidae). Zootaxa 2173, 1-18.

58. Lund R. 1985 The morphology of Falcatus falcatus St. John & Worthen, a Mississippian stethacanthid chondrichthyan from the Bear Gulch Limestone of Montana. J. Vert. Paleontol. 5, 1-19.

59. Lund R. 1982 Harpagofututor volsellorhinus new genus and species (Chondrichthyes, Chondrenche-lyiformes) from the Namurian Bear Gulch Lime-stone, Chondrenchelys problematica Traquair (Visean), and their sexual dimorphism. J. Vert. Pa-leontol. 56, 938-958.

60. Kubota T, Shiobara Y, Kubodera, T. 1991 Food habits of the Frilled Shark Chlamydoselachus an-guineus Collected from Suruga Bay, Central Japan. Nippon Suisan Gakk. 57(1), 15-20.

61. Sallan LC, Coates MI. 2010 End Devonian ex-tinction and a bottleneck in the early evolution of modern jawed vertebrates. Proc. Natl. Acad. Sci. 107(22), 1013110135.

62. Friedman M, Sallan LC. 2012 Five hundred mil-lion years of extinction and recovery: a Phanerozo-ic survey of large-scale diversity patterns in fi shes. Palaeontology, 55(4), 707-742.

63. Giles S, Xu GH, Near TJ, Friedman M. 2017 Early members of ‘living fossil’lineage imply later origin of modern ray-fi nned fi shes. Nature, 549(7671), 265.

102

Chapter III: Phoebodontid Chondrichthyans of the Maider

Fig. S1. Geological map of the southeastern Anti-Atlas of Morocco. The Thylacocephalan Layer with gnathostomes crops out in the Maïder region. Remains of Phoebodus were collected from the Famennian (Late Devonian) of Madene (30°44`407`` N, 4°42`899``W; 30°47`188`` N, 004°40`965`` W).

SUPPLEMENTARY FIGURES

103

Chapter III: Phoebodontid Chondrichthyans of the Maider

Fig. S2. Phoebodus saidselachus sp. nov. (PIMUZ A/I 4659), neurocranium and jaw fragments with mandibular teeth. (a) dorsal and (b) lateral aspects, scale bar = 100 mm. (c) ventral aspect of the anterior part of the snout and jaws with exposed tooth families, scale bar = 50 mm. j. frag, jaw fragments; n, neurocranium; pq, palatoquadrate; ros, rostrum; t, teeth.

104

Chapter III: Phoebodontid Chondrichthyans of the Maider

Fig. S3. Phoebodus saidselachus sp. nov. (PIMUZ A/I 4710), Meckel`s cartilages (mc) with intact anterior tooth whorls in situ (t). (a) ventral view, scale bar =100 mm. (b) detail and (c) drawing of the at least six most anterior tooth families of the right ramus of the lower jaw, scale bar = 10 mm. mc, Meckel`s cartilage; t, teeth.

Fig. S4. Braincase of Phoebodus sp. (PIMUZ A/I 4713). (a) Weathered specimen and (b) illustration in dorsal view; scale bar = 100 mm. asc, anterior semicircular canal; end.d, endolymphatic ducts; end.f, endolymphatic fossa; into, interorbital space; occ, occipital cotylus; psc, posterior semicircular canal; pop, postorbital process; soc, spino-oc-cipital canal.

105

Chapter III: Phoebodontid Chondrichthyans of the Maider

Fig. S5. Reconstructed braincase, mandibular and visceral arches of Phoebodus sp. (PIMUZ A/I 4711): (a) anterior, (b) posterior, (c) lateral, (e) dorsal and (f) ventral view. Colour coding: grey, braincase; orange, ceratohyal; blue, hy-omandibulare; turquoise, palatoquadrate; yellow, Meckel`s cartilage; light blue, fragments of ?epibranchials; purple, branchial elements; red, ?ceratobranchial; green, part of ?palatoquadrate.

106

Chapter III: Phoebodontid Chondrichthyans of the Maider

Fig. S6. Phoebodus saidselachus sp. nov. (PIMUZ A/I 4712), dorsal fi n spines. Lateral view of (a) anterior and (b) posterior dorsal fi n spines, scale bar = 50 mm. (c) detail showing ctenacanthid ornamentation, scale bar = 10 mm.

107

Chapter III: Phoebodontid Chondrichthyans of the Maider

Fig. S7. Phoebodus saidselachus sp. nov. (PIMUZ A/I 4712), mandibular teeth. Photo of the dentition with explana-tory drawing (a); scale bar = 10 mm. (b - e) detail of the dentition, photo with explanatory drawing, (b,c) oral views of teeth, (d) teeth in aborolateral view, (e) lateral cross-section of teeth in a row. Scale bars in (b-e) = 5 mm.

108

Chapter III: Phoebodontid Chondrichthyans of the Maider

Fig. S8. Scales in the cranial region of Phoebodus sp. (PIMUZ A/I 4713). Scale bar = 5 mm.

109

Chapter III: Phoebodontid Chondrichthyans of the Maider

Entelognathus

Youngolepis

Guiyu

Psarolepis

Cheirolepis

Mimipiscis

Raynerius

Moythomasia

Culmacanthus

Ischnacanthus

Nerepisacanthus

Poracanthodes

Tetanopsyrus

Uraniacanthus

Diplacanthus

Rhadinacanthus

Cassidiceps

Mesacanthus

Promesacanthus

Cheiracanthus

Acanthodes

Homalacanthus

Halimacanthodes

Gladbachus

Brachyacanthus

Brochoadmones

Climatius

Parexus

Ptomacanthus

V waynensis

Gyracanthides

Latviacanthus

Pucapampella

Kathemacanthus

Lupopsyrus

Obtusacanthus

Doliodus

Acronemus

Egertonodus

Hamiltonichthys

Onychoselache

Tribodus

Squalus

Synechodus

Tristychius

Homalodontus

Cladodoides

Phoebodus

Thrinacodus

Diplodoselache

Orthacanthus

Triodus

Tamiobatis

Dwykaselachus

Ozarcus

Cladoselache

Cobelodus

Akmonistion

Damocles

Falcatus

Debeerius

Chimaeroidei

Chondrenchelys

Helodus

Iniopera

Kawichthys

5/100

5/79

4/75

24/83

3/73

5/98

4/57

4

2

4

33

5

5

25/76

3

5?/51

3/53

4

2

50

60

Fig

. S

9. S

tric

t co

nsen

sus

tree

inc

ludi

ng v

alue

s of

Bre

mer

`s d

ecay

and

boo

tstr

ap s

uppo

rt a

t sp

ecifi

c k

nots

. Bre

mer

sco

res:

3, g

ood

supp

ort;

5, h

ighl

y su

ppor

ted.

Boo

stra

p va

lues

: m

ore

than

50:

wea

k su

ppor

t, m

ore

than

75;

goo

d su

ppor

t; 1

00:

high

est

supp

ort.

Col

our

codi

ng:

blac

k, s

tem

gro

up g

nath

tost

ome

(out

grou

p);

gree

n, O

stei

chth

yes;

red

, Aca

ntho

dii

(ste

m C

hond

rich

thye

s); o

rang

e, s

tem

Cho

ndri

chth

yes

excl

udin

g A

cant

hodi

i; b

lue,

Ela

smob

ranc

hii (

crow

n C

hond

rich

thye

s); p

urpl

e, H

oloc

epha

li (

crow

n C

hond

rich

thye

s).

110

Chapter III: Phoebodontid chondrichthyans of the Maider

SUPPLEMENTARY NOTES

1) Devonian gnathostomes of Morocco

Morocco is famous for its often highly fossiliferous Devonian outcrops, which bear sometimes abundant invertebrates but also, somewhat rarer, inarticulated as well as articulated remains of vertebrates. Concern-ing vertebrates, macro- and microremains of placoderms and sarcopterygians are locally abundant in some strata and they were repeatedly reported from the Tafi lalt and Maïder regions of the southeastern Anti-Atlas (Lehmann 1956, 1964, 1976, 1977, 1978; Lelièvre & Janvier 1986, 1988; Lelièvre et al. 1993; Rücklin 2010, 2011; Rücklin et al. 2015, Rücklin & Clément 2017). Many taxa of Devonian chondrichthyans (e.g. Jalodus, Thrinacodus, Phoebodus, Ctenacanthus, Stethacanthus, Symmorium, Cobelodus, Denaea, Oro-dus, Protacrodus, Siamodus, Clairina) are documented by abundant isolated teeth and fi n spines, while cartilaginous structures such as a jaw were documented only once thus far (Lehman 1976; Derycke, 1992; Hampe et al. 2004; Derycke et al. 2008; Ginter et al. 2002; Derycke 2017). Only recently, more or less complete skeletons and braincases of chondrichthyans were found in the southern Maïder Basin (Fig. S1). The skeletal remains are preserved in ferruginous clayey nodules of reddish color found in the early/ mid-dle Famennian Thylacocephalan Layer in which thylacocephalans are highly abundant (Frey et al. 2018). Phoebodus is accompanied by numerous haematitic internal molds of cephalopods and phosphatised thyla-cocephalan as well as a few benthic invertebrates (Buchiola, Guerichia, ostracods and brachiopods). Con-cerning other gnathostomes, several species of well-preserved placoderms, sarcopterygians and cladodont chondrichthyans were found in and above the Thylacocephalan Layer. The palaeoenvironment at Madene el Mrakib was, during much of the Famennian stage, characterized by well-oxagenated waters in much of the water column while deeper water levels near the sea fl oor were oxygen-depleted, as inferred from the scarcity and low diversity of benthic invertebrates and the absence of bottom dwelling vertebrates (Frey et al. 2018). Taxa of invertebrates and vertebrates inhabiting higher water levels were more common and diverse, thus suggesting a better oxygenated water column.

2) Systematic Paleontology and specimen description

Class Chondrichthyes Huxley, 1880B

Subclass Elasmobranchii Bonaparte, 1838B

Family Phoebodontidae Williams in Zangerl, 1981

Included genera – Phoebodus St. John & Worthen, 1875A; Thrinacodus St. John & Worthen, 1875A; tentatively Diademodus Harris, 1951.

Family defi nition – Multicuspid teeth; three long main cusps intercalated by two small intermediate cus-plets; main cusps are sigmoidal; modestly ornamented cusps showing subparallel cristae; basis with lingual torus containing a single button for articulation; arcuate basolabial projection.

Remarks – The family Phoebodontidae includes the genera Diademodus, Phoebodus and Thrinacodus. While Phoebodus was only known from teeth for a long time, skeletal remains of Diademodus hydei Harris, 1951were found in the Devonian Cleveland Shales of Ohio, USA and complete skeletons of Thri-nacodus gracia (Grogan & Lund, 2008) were described from the Carboniferous of Bear Gulch, Montana. However, the inclusion of Diademodus in the Phoebodontidae is arguable as its teeth show multiple small cusps in contrast to the three large main cusps in Phoebodus (Ginter et al. 2010). Thrinacodus was as-signed to the family Thrinacodontidae by Grogan & Lund (2008) due to differences in tooth and base shape compared to Phoebodus. However, the differences are too weak to keep Thrinacodus in a separate family and therefore, it was suggested to place Thrinacodus together with Phoebodus within the Phoebodontidae (Long 1990; Ginter & Turner 2010).

111

Chapter III: Phoebodontid chondrichthyans of the Maider

Genus Phoebodus St. John & Worthen, 1875A

Type species – Bathycheilodus macisaacsi St. John & Worthen, 1875A, later named Phoebodus macisaa-csi Wells, 1944C and fi nally Phoebodus sophiae Ginter et al., 2010.

Stratigraphical and geographical distribution– Givetian to Famennian; nearly cosmopolitan.

Diagnosis – emended genus diagnosis, see main article.

Phoebodus saidselachus sp. nov.

Holotype – PIMUZ A/I 4712

Stratigraphic and geographic occurrences – early to middle Famennian of the Madene (30°44`407`` N, 4°42`899``W) and Aguelmous, Maïder region, Anti-Atlas, Morocco.

Material – One nodule with cranial and postcranial material (PIMUZ A/I 4712) and two braincases (PIMUZA/I 4656, PIMUZ A/I 4710).

Derivation of name – After Said Oukherbouch (Tafraoute), the fi rst name of our Moroccan collaborator in the fi eld (the Arabic word ديعس means ‘happy’), and the Latin word selachus (shark).

1. Specimen PIMUZA/I 4656 and PIMUZ A/I 4710

Mandibular dentition and tooth morphology – Several mandibular tooth fi les are exposed in specimen PIMUZ A/I 4656 and PIMUZ A/I 4710 (Fig. S2c; S3b-c). The teeth are weathered, very soft and encrusted by a hard ferruginous layer. Removing these crusts by preparation results in destruction of the fossil ma-terial with its structure. Therefore, very little of the fi ner morphological details is visible. PIMUZ A/I 4656 bears six, probably seven tooth fi les separated by gaps in the anterior parts of the upper jaws and in PIMUZ A/I 4710, six tooth fi les are countable in the anterior region of the lower jaws.

Tooth fi les 1 to 3 of the upper left and fi les 1 to 2 of the upper right jaw in PIMUZ A/I 4656 contain three teeth, which are exposed from mostly labial and orolabial aspects (Fig. S2c). In PIMUZ A/I 4710, between two and six teeth are countable within the tooth fi les and several views are exposed (1A-D: labial; 2B: aborolabial; 3A-B: lingual; 4A-F: aboral and orolateral; 5A-C:?; 6A-B: oral and labial; Fig. S3b,c). PIMUZ A/I 4656 shows a single tooth that is well-preserved and which is exposed from labial, lateral and oral sides (Fig. S2c: tooth 4A; Fig. 1e). Labially, there is a large median cusp and two large lateral cusps of nearly identical length, but the lateral cusps appear to be more massive and broader in diameter than the median cusp (Fig. 1e). All main cusps are lingually recurved and show a sigmoid outline in lateral view. Between the large central and lateral cusps, there are two minute intermediate cusplets reaching maximally half of the length and thickness of the central cusp. Each main cusp shows an ornamentation consisting of two distinct striae forming rather sharp edges. The tooth base is squarish with rounded angles in ab-oral view and is 5.2 mm wide and 4.5 mm long. From labial, aboral and lateral aspects, the base shows a concave outline. The basolabial projection is wider than the median cusp and consists of a labiolingually narrow and slightly arcuate prominence. A large aboral foramen of the main basal canal lays lingually to the basolabial projection. In PIMUZ A/I 4710, a single tooth (Fig. S3b-c, 2b) with a well-preserved base of the same morphology is present, which shows that the two specimens are conspecifi c.

The dentition of Phoebodus saidselachus sp. nov. is homodont when size and shape of all preserved teeth are compared among each other. Size appears to differ hardly among teeth of the same tooth fi le, but this might be a view biased by the insuffi cient preservation or exposure of only parts of each tooth whorl. Grogan & Lund (2008) reported a homodont dentition from Thrinacodus gracia, while Ginter & Turner (2010) described a minor heterodonty (teeth between lower and upper jaw and between anterior and poste-rior positions differ in size and symmetry) based on unarticulated teeth of Thrinacodus ferox.

112

Chapter III: Phoebodontid chondrichthyans of the Maider

Neurocranium and mandibular arches - Neurocranial and mandibular remains of Phoebodus saidse-lachus sp. nov. are three-dimensionally preserved but embedded in ferruginous rocks or covered by fer-ruginous crusts and therefore, anatomical details are hardly exposed. Internal structures of the braincase are recognizable in some cross-sections. Computer tomography scanning and neutron scanning resulted in image stacks of insuffi cient contrast because of hydroxyl-rich compounds in the host rocks. Thus, the morphology of the cranial region of the specimens is here described only superfi cially.

In PIMUZ A/I 4656, a ferruginous crust revealed the outline of the braincase, palatoquadrates and Meckel`s cartilages (the rock containing all these elements measures 0.33 m in length). In dorsal and ventral view, the skull becomes increasingly slender from posterior to anterior and anteriorly ends in a rounded and somewhat blunt snout that is much less pointed than in Thrinacodus gracia (Fig. S2a, c). The overall shape of the skull is elongated and slender compared to most Palaeozoic chondrichthyans but less slender than in the more derived phoebodont Thrinacodus gracia. Laterally, fragments of the long jaws are present that fl ank the entire specimen (Fig. S2b, c). In PIMUZ A/I 4710, parts of both Meckel`s cartilages are exposed and show no symphysial fusion anteriorly, which is the common condition in Palaeozoic chon-drichthyans (Fig. S2c, S3a). Anterior to the lower jaws, teeth are present whose sizes are small compared to jaw dimensions. These proportions appear to correspond well with the reconstructions of Thrinacodus (Grogan & Lund, 2008).

Remarks - Quite a few species of Phoebodus based on teeth with almost identical crowns and only minor differences in the bases were described from the Famennian. These are: Ph. rayi (Ginter & Turner, 1999), Ph. typicus (Ginter & Ivanov, 1995), Ph. turnerae (Ginter & Ivanov, 1992), Ph. gothicus (Ginter, 1990), and Ph. politus (Newberry, 1889). Ph. rayi (Ginter & Turner, 1999) and Ph. turnerae (Ginter & Ivanov, 1992) can easily be removed from the comparison with Ph. saidselachus sp. nov., because their orolingual button is not situated in the centre of the base, but at the lingual rim. Most specimens of Ph. gothicus have much longer bases, which are lingually rounded or end with an angle. However, the teeth of Ph. typicus and Ph. politus are very similar to those of Ph. saidselachus sp. nov. and in fact, they can easily be confused among each other. Tooth bases of Ph. typicus are more rectangular and wider than in Ph. saidselachus sp. nov., while the tooth bases are more circular in Ph. politus. The published teeth of the latter species (New-berry 1889, pl. 27, fi gs 27, 28; Eastman 1907, pl. 7, fi g. 5; 1908, pl. 1, fi g. 9) are relatively large and about the same size as Ph. saidselachus sp. nov. (base width about 7-8 mm), whereas all the known teeth of Ph. typicus do not exceed 2 mm. As far as the tooth morphology is concerned, Ph. saidselachus sp. nov. is situated between the older species (Ph. typicus, early-middle Famennian) and the younger one (Ph. politus, late Famennian).

2. Specimen PIMUZ A/I 4712

Mandibular dentition and tooth morphology - Remains of small partially articulated teeth lie in the space between the right upper and lower jaw (Fig. 1a,c). All teeth are extremely fragile and it is not possi-ble to extract one without damaging it signifi cantly. The diagnostic morphological details of the tooth base is often not exposed or not preserved. However, some bases show a rounded outline lingually similar to specimen PIMUZA/I 4656 and PIMUZ A/I 4710. Therefore, we assign all three specimens to Phoebodus saidselachus sp. nov.

In labial aspects, the teeth show the characteristic crown shape of phoebodontids with three long main cusps (one median and two laterals) of similar length. In oral view, the cusps appear to recurve subtly lin-gually (Fig. S7c). Very faint traces of cross-sections of minute intermediate cusplets between the central and lateral cusps are present in two teeth (Fig. S7b,c). Cusp ornamentation is either not preserved or not present. In oral and aborolateral aspects, the preserved remains of the tooth bases show a rather subcircular or probably slightly rectangular outline. Lingually and close to the crown, a single orolingual button of oval shape is visible. This protrusion is wider than the central cusp and covers around half of the labiolin-gual length of the base (Fig. S7b). Posterior to the orolingual button, the lingual opening of the main basal canal is situated. In aborolateral view, the base shows remains of an elliptical concavity in the center, which serves as an articulation surface for the orolingual button of a former tooth (Fig. S7d). Cross-sections of lateral aspects of tightly packed teeth are visible in some jaw regions (Fig. S7a, e). The articulated teeth do

113

Chapter III: Phoebodontid chondrichthyans of the Maider

not differ measurably in size among each other. In lateral view, the base shows sometimes an aborolingual concavity, which fi ts to the orolingual convexity of the former tooth.

The preserved teeth let assume that the dentition of the described specimen of Phoebodus was homo-dont: its teeth do not signifi cantly differ in size or shape within or between jaw types. There are few teeth that look slightly different: the most posterior tooth (marked with an asterisk in Fig. S7a) appears to have a stouter crown with median and lateral cusps showing a wider diameter compared to the other teeth. A second tooth shows a much bigger base from the oral aspect (marked with asterisk in around the middle of Fig. S7a). However, mostly the crowns are exposed or preserved, which are less diagnostic on the species level than the tooth bases.

Body form and proportions - In PIMUZ A/I 4712, the right and left Meckel`s cartilage, the right pala-toquadrate, some parts of the branchial and postcranial skeleton (shoulder girdles, pelvic fi n remains, dorsal fi n spines, neural arches) and traces of the body outline are present (Fig. 1a,b). The caudal region is largely eroded. According to this specimen, Phoebodus had an elongated, anguilliform body shape similar to Thrinacodus, but less slender. The entire specimen measures 0.98 m from the preserved anterior edge of the jaws to the most posterior fragment of cartilage. However, this specimen was longer; based on the length of the nodule, which usually corresponds roughly to the shape of the incorporated carcass, we esti-mate that the complete animal was at least 1.2 m long. The jaws are long and delicate measuring 0.18 m, although the anterior ends of the jaws are missing. The distance between the anterior end of jaws to the fi rst dorsal fi n spine measure 0.38 m and the distance between the fi rst and second dorsal fi n spines is 0.4 m. The body height of Phoebodus is low but both relatively and absolutely higher than in Thrinacodus (only 20 mm high): In PIMUZ A/I 4712, the anterior part of the lower and upper jaws together is around 0.05 m high, the branchial arch region around 0.11 m and the thoracic region around 0.14 m high. Estimated body proportions are as follows: jaw length to body length maximal 15% (Thrinacodus: head length to body length 8.5%) and body height to body length maximal 11% (Thrinacodus: 3%).

Mandibular arches - The right and left Meckel`s cartilage (mc) as well as the right palatoquadrate (pq) are exposed from the lateral and slightly ventral view (Fig. 1c). Anteriorly, the tips of the lower jaws and palatine rami are missing. Estimation of the missing nodule part is approximately 50 mm in anteroposterior length. Like in Thrinacodus gracia, there are no traces of labial cartilages that are a common feature in hybodonts and recent chondrichthyans.

All jaw elements are elongated, which contrasts the mandibular conditions in many other Palaeozoic chondrichthyans (xenacanthids, cladoselachians, symmoriids and hybodontids). This morphological trait segregates Phoebodus from Heslerodus that was previously described as Ph. heslerorum (Zangerl 1981; Stahl 1988) and therefore supports the teeth-based revision of Ginter (2002). In contrast to Thrinacodus gracia, where the palatoquadrate is much shorter than Meckel`s cartilage, both upper and lower jaws are elongated to roughly the same extend in Phoebodus. In Ph. saidelachus sp. nov. (PIMUZ A/I 4656) de-scribed in this work, the upper jaw appears to reach some millimeters anterior of the lower jaw (Fig. S2c).

Both Meckel`s cartilages are exposed from lateral and slightly ventral aspects and show an anteriopos-teriorly elongation. The overall slender shape resembles the lower jaws of chlamydoselachids, xenacan-thids and Thrinacodus gracia. The posterior half is dorsoventrally about the same height as the quadrate re-gion of the palatoquadrate. Towards the anterior end of the nodule, Meckel`s cartilage is slightly narrowing dorsoventrally. Posteriorly, the dorsoventral outline thins out and forms an amphistylic articulation with the palatoquadrate. The dorsal edge of the right lower jaw is slightly concave anterior to the articulation; it is also rather straight along the rest of the jaw. Posteroventrally, the edge of the right jaw fl ips laterally forming a rim.

The ventral edge of the right palatoquadrate is covered anteriorly by teeth and posteriorly by Meckel`s cartilage. A little dorsal to the ventral edge and anterior to the articulation of the jaws, a prominent lateral ridge (80 mm long and 10 mm high) extends from the quadrate region and runs in parallels across two thirds of its anteroposterior length (Fig. 5, 7a-c; mcr). However, this ridge might have formed due to ta-phonomic alteration such as compcation. The quadrate region is dorsoventrally only slightly broader than the suborbital palatine, which differs from the condition in Thrinacodus gracia, the xenacanthids and the symmoriiforms. Similar conditions with a dorsoventrally relatively short quadrate region are known from

114

Chapter III: Phoebodontid chondrichthyans of the Maider

recent Chlamydoselachus and hybodontids, although in latter one the quadrate region is laterally expanded forming a quadrate fl ange (Smith 1937; Maisey 1982, 1986). In Phoebodus, the posterodorsal edge of the quadrate region is fl ipped laterally, thus forming a strong posterolateral rim where the adductor muscles are inserted. The remains of the suborbital palatine ramus are slightly narrower dorsoventrally than the quadrate region.

Hyoid and gill arches - The basihyal (bh), a ceratohyal (ch) and two ceratobranchials (cb) are preserved (Fig. 1c). Additional branchial arches might be preserved, but they are hardly distinguishable from each other due to its mode of preservation. Branchial rays are either not present or not preserved and were also not described from Thrinacodus gracia (Grogan & Lund 2008).

A long triangular cartilage lies posterior to the point where the lower jaws meet. This cartilage proba-bly represents the basihyal in ventral aspect. A comparable structure was not described from Thrinacodus (Grogan & Lund 2008) but the position of the cartilage corresponds to the subtriangular anteriormost ba-sibranchial documented for Akmonistion and Stethacanthus (Coates & Sequeira 2001; Lund 1985a). Other basibranchial elements such as those described from Cobelodus (Zangerl & Case 1976) and Heslerodus (Williams 1985) were not found in Phoebodus.

The left ceratohyal articulates posteriorly to the basihyal and it parallels the left Meckel`s cartilage. It is exposed from its lateral aspect posteriorly and from the ventrolateral aspect anteriorly. The ceratohyal mea-sures between around 1/2 and 1/3 of the mandibular length and posteriorly, it curves to the same degree as the posteroventral edge of the left Meckel`s cartilage. It is rather straight in profi le compared its semicres-cent shape in symmoriids, cladoselachids (Coates & Sequeira 2001) and xenacanthids (Heidtke & Schwind 2004). Moreover, unlike in Akmonistion zangerli (Coates & Sequeira 2001), the ceratohyal of Phoebodus is not uniformly thick throughout its length: its posterior edge is dorsoventrally broad but towards the ante-rior end, the cartilage is narrowing. In ventral view, the ceratohyal is narrow over around 3/4 of its length, but in its anteriormost quarter, the ventral surface is laterally expanding and forms a fl ange (anteriorly blade-like shaped) articulating anteriorly with the basihyal. A similar medial fl ange is present in Tristychius arcuatus (unpublished information M. Coates). There is no hypohyal anterior to the ceratohyal such as it is present in Thrinacodus gracia and xenacanthids (Triodus and Xenacanthus; Heidtke et al. 2004).

Remains of ceratobranchials are preserved dorsal to the left ceratohyal. There is a rod-shaped rest of a ceratobranchial of slightly shorter length than the ceratohyal. Weak traces of two additional ceratobranchi-als are exposed above the relatively well-preserved ceratobranchial. Other elements such as epibranchials, hypobranchials and pharyngobranchials cannot be determined with certainty, although the body outline adumbrates the presence of more branchial elements.

Pectoral girdle and fi ns - The scapulacoracoid (sc) is partially preserved in PIMUZ A/I 4712. From the pectoral fi n, fragments of the metapterygium and remains of fi ve tightly packed radials (rad) or basals alike Thrinacodus are preserved (Fig. 1a, b). Dorsally, the scapula is broken and there is no information about anterodorsal and posterodorsal processes preserved. The scapula and coracoid are fused and their shape re-sembles the scapulacoracoids of symmoriids. The coracoid region is anteriorly convex and there is a broad ventral concavity probably serving as an articular surface for fi n radials. On the posterior edge of the cora-coid, there is a rather deep and small concavity; however, this concavity could be the result of taphonomic alteration. Coracoid plates separated from the scapula such as in Thrinacodus gracia (Grogan & Lund 2008) are absent in Phoebodus. Posterior to the coracoid, there are possible fragments of a metapterygium (mpt) that is articulated to fi ve poorly preserved radials.

Pelvic girdle and fi ns - On the ventral side of the specimen at the position of the second dorsal fi n spine, the nodule extends into a fi n-like protrusion, probably documenting the former presence of pelvic fi ns and their position (Fig. 1a, b). Below the second dorsal fi n spine, several remains of cartilage are visible. The different cartilages are hardly distinguishable from each other. Two of these cartilages may represent remains of radials (rad).

Dorsal fi n and fi n spines - Radials of dorsal fi ns are absent but faint traces of cartilage (adbc, pdbc, Fig. 1a,b) are located posterioventrally to both fi n spines. Probably, this cartilage was serving as a support for the fi n spine like the triangular basal elements in hybodonts (Maisey 1982). Two fi n spines are well exposed in association with the anterior and posterior dorsal fi ns (fs, Fig. 1a, b, Fig. S6a, b). Both spines

115

Chapter III: Phoebodontid chondrichthyans of the Maider

are closely aligned to the body outline, but their orientation could have been altered taphonomically while their relative positions appear to correspond to their primary relative positions, at least with respect to their distance from each other. The anterior fi n spine is proximodistally longer and anteroposterioly thicker than the posterior one. The fi n spines are slender, slightly recurved, deeply inserted and in that respect resemble Sphenacanthus aquistriatus and Amelacanthus (Maisey 1982). Their edges are smooth and the dorsal edg-es of both fi n spines are slightly convex while the ventral spine wall is slightly sigmoidal in profi le (pos-teriorly, the last third of the spine length shows a subtle concavity). The ornamentation of the fi n spine is poorly visible because most of the spine surface is weathered. There still are some remains of ctenacanthid ornaments (Fig. S6c) consisting of regular costae intercalated by narrow intercostal grooves and transverse ridges interrupting the costae regularly, giving the ornament a zipper-like appearance.

Axial Skeleton - Ventral to the anterior dorsal fi n spine, remains of neural arches are discernible (Fig. 1a, b). Anteriorly, it is not possible to visually separate the neural arches from each other. Towards the posteri-or, the outlines of twelve neural arches of vertebrae become clearer. The dorsal edge of the closely packed, slender and rod-shaped neural arches are directed posteriorly. Among the preserved arches, the posterior arches are dorsoventrally longer than the more anterior ones forming a crest-like structure; it is not clear whether this might be due to a taphonomic alteration (e.g., compaction, collapse, etc.). Vertebral elements such as interventrals, basidorsals, basiventrals and hemal spines were described in Thrinacodus but these are not preserved in the Phoebodus specimen described here.

Remarks - In spite of its unique completeness, especially when compared to the previously known fossil record of Phoebodus consisting of countless teeth mainly, the preservation of the here described specimen is far from perfect. For example, the caudal fi n and much of both pelvic and pectoral fi ns are missing. This is quite characteristic for the taphonomy of the gnathostomes of the Thylacocephalan Layer in the southern Maïder (Frey et al. submitted). Usually, the fi sh remains are incorporated in large fl at nodules rich in hae-matite and limonite. The head and gill regions usually is encased in the thickest part of the nodule, while most of the postcranium lies on top of the nodule that thins out posteriorly. In some rare cases, the caudal fi n still rests on the nodule while in most other cases, the posterior of the skeletons is eroded, because it was embedded in the deeply weathered crumbling claystone. Nevertheless, the shape of the nodules very roughly traces the outline of the former carcass, thus documenting the overall body shape, position of fi ns and their rough dimensions. Based on this indirect evidence, we suggest that the caudal fi n resembled that of Thrinacodus in lacking strongly developed dorsal and ventral lobes as in, e.g., modern elasmobranchs like Carcharodon. Instead, the caudalis probably had a shape like that known from Thrinacodus (but less elongate) or Cladoselache.

Phoebodus sp.

Specimen PIMUZ A/I 4711 and PIMUZ A/I 4713

Neurocranium - In PIMUZ A/I 4713, the dorsal portion of the otic and occipital region and a small part of the interorbital space is preserved. In PIMUZ A/I 4711, computer tomographies provide anatomical insights into the otic region including semicircular canals and the entire occipit.

The preserved remains of the postorbital process indicate a short, anteroposteriorly narrow process (Fig. S4). In the otic region, the anterior and posterior semicircular canals dorsally unify to a crus commune such as in symmoriiforms, Cladodoides and xenacanthids. Therefore, Phoebodus likely had no for phono-reception. The endolymphatic chamber is narrow anteriorly and broadens dorsally; paired endolymphatic ducts are located anterior to the crus commune (Fig. S4). The endolymphatic fossa is narrow and laterally fl anked by prominent dorsal otic ridges (Fig. 2a-d, S5a-e), which closely resembles the condition seen in Tamiobatis, Orthacanthus, and Tristychius (Williams 1998; Schaeffer 1981; Coates & Tietjen 2018). This shape of the endolymphatic fossa is in contrast to the ovoid shape in Stethacanthus Newberry, 1889, Ak-monistion Coates & Sequeira, 2001 and Dwykaselachus Oelofsen, 1986. Similar to the condition in Clado-doides, the glossopharyngeal canals are fl oored by a massive hypotic lamina, which hosts two openings for the lateral dorsal aortae posteriorly (Fig. 2b). Therefore, the dorsal aorta splits posterior to the occipital

116

Chapter III: Phoebodontid chondrichthyans of the Maider

level like in Cladodoides, Tamiobatis, Tristychius and xenacanthids (Maisey 2005; Schaeffer 1981; Coates & Tietjen 2018).

The occipital region is elongated compared to other early and modern elasmobranchs but might be similarly elongated in the phoebodont Thrinacodus gracia (Fig. S4a-b; fi g. 10C in Grogan & Lund 2008). On the right lateral side of the occiput, traces of three canals for the spino-occipital nerves are preserved. Moreover, the prominent supraoccipital crest is a common feature of Phoebodus, Tristychius, and xenacan-thids (Schaeffer 1981; Coates & Tietjen 2018).

Branchial arches – Remains of hyoids articulate at the periotic region of the braincase (Fig. S5a, e). They are fl at, dorsoventrally broad and slightly curved. Anteriorly, the ceratohyals anteriorly have a fl ange like in PIMUZ A/I 4712 (Fig. 1c, 2i, S5a, e). Remains of mandibular and gill arches with little anatomical details are preserved (Fig. S5a-f): the palatoquadrate has fl ipped to the ventral side of the braincase and it has been recognized by the presence of the dorsal crest of the otic process (Fig. S5f).

Endocast – The reconstructed endocast (Fig. 3a-e) shows parts of the sacculum, the external and posterior semicircular canals, and the medulla. Like in symmoriids, xenacanthids and Cladodoides, the posterior semicircular canals form a wide arch each and unify with the posterior ampullae. The medulla of Phoebo-dus is anteroposteriorly long which resembles the condition in other elasmobranchs such as Cladodoides and xenacanthids (Maisey 2007; Schaeffer 1981).

Body squamation - Multicuspid scales are preserved in the head region of PIMUZ A/I 4713. Due to their poor preservation and because they are embedded in the host rock, a morphological description is impos-sible at this point (Fig. S8).

3) Taxa and sources

The taxa list was adopted from Coates et al. (2018). 22 taxa of stem gnathostomes (including Agnatha, Placodermi and some Osteichthyes) were excluded from the phylogenetic analyses as they were not rele-vant for the position of the phoebodontid chondrichthyans within the chondrichthyan phylogeny.

Acanthodes: Benznosov 2009; Brazeau & de Winter 2015; Coates 1994; Davis et al. 2012; Heidtke 1993, 2011a,b; Jarvik 1977, 1980; Miles 1968, 1973a, b; Nelson 1968; specimens AMNH 1037b, 10370, 10376, 19628; CMNH 30725b, 30726, 4591; FMNH PF2875; GM C145, 146, 180; HM V8251, 252; HU MB.F.4209, 4277, 4284, 4285, 7286, MB3b, 4a & b, 5a & b, 7a & b, 8a & b, 11a & b, 12a, 13a &b, 14a &b, 16a &b, 17a & b, 18a & b, 23 (resin copy), 24, MM L1693, 1698, 9432B, W1994; NHM P.11287, P.13139, 13140, 14558, 1728, 34912, 34914, 4057, 49941, 49944, 49959, 49967, 49979, 49980, 49990, 49995, 49996, 60928, 60939, 62138, 7335; NMS 2001.7.1, 3; UCL GM C1126; UMZC GN9, 11, 13, 14, 15a &b, 16, 39, 756.

Acronemus: Maisey 2011; Rieppel 1982.Akmonistion: Coates & Sequiera 1998, 2001a, b; Coates et al. 1998; Coates et al. 2017.Brachyacanthus: Denison 1979; Miles 1973a; Watson 1937; specimens NMS Kinnaird 88, NMS (Powrie)

1891.92.212, 213, 214, 220, 222, 224, 225, 226, 227.Brochoadmones: Bernacsek & Dineley 1977; Gagnier & Wilson 1996b; Hanke & Wilson 2006; specimens

UALVP 32672, 41487, 41493, 41494, 41495.Callorhinchus/Hydrolagus: Cole 1896; De Beer 1937; De Beer & Moy-Thomas 1935; Didier 1995; Didier

et al. 1994, 1998, 2012; Howard et al. 2013; Kesteven 1937; Patterson 1965, 1992; Pradel et al. 2013; Stahl 1999.

Cassidiceps: Gagnier & Wilson 1996a; specimen UALVP 32454.Cheiracanthus: Denison 1979; Miles 1973a; Watson 1937; specimens AMNH 317, 6929, 7082; GM C295,

296, 325, 490; HM V7614; IC 214, 215, 216, 217; UMZC GN14a &b, 19, 20, 21, 31, 50; 1131a & b, 1132a & b, 1133a & b, 1134a & b, 1135a & b, 1136a & b, 1137a & b, 1138, 1139, 1140.

Cheirolepis: Arratia & Cloutier 1996; Pearson & Westoll 1979; Giles et al. 2015a.Chondrenchelys: Finarelli & Coates 2012, 2014; Lund 1982; Moy-Thomas 1935; specimens NMS

1885.54.5/5A, 1891.53.33, 1998.35.1, 2002.68.1; BGS-GSE 13328; HM V.7173.

117

Chapter III: Phoebodontid chondrichthyans of the Maider

Cladodoides: Gross 1937, 1938; Maisey 2005.Cladoselache: Bendix-Almgreen 1975; Harris 1938a, b; Maisey 1989a, 2007; Schaeffer 1981; Williams

2001; Woodward & White 1938; specimens CMNH 8110, 8111, 8207, NHM P9273, P9285.Climatius: Miles 1973a, b; Watson 1937: specimens AMNH 7762; GSM 49785; MM L12096a & b; NMS

Kinnaird 80; NMS 1881.5.62; NMS 1887 (Peach) 35.3a, 35.5b, 35.5e; NMS 1891 (Powrie) 92.195, 204, 206, 214; NMS 1967.12.4; NMS 1973.9.4; NMS 2001.7.2.

Cobelodus: Zangerl & Case 1976; Zidek 1992.Culmacanthus: Long 1983.Damocles: Lund 1986: specimens CM 35472, 48760.Debeerius: Grogan & Lund 2000: specimens CM 35479, 35480, 48831, 62811.Diplacanthus: Gagnier 1996; Miles 1973a; Watson 1937; specimens FMNH PF11633; GM C12, 13, 148;

GM P482; MM L5503, 1609; NMS (Powrie) 1891.92.334; NMS 2001.7.4; UMZC GN17, 18, 22.Diplodoselache: Dick 1981.Doliodus: Miller et al. 2003; Maisey et al. 2009, 2013, 2017; Long et al. 2015.Dwykaselachus: Coates et al. 2017; Oelofsen 1986; specimen SAM K5840.Egertonodus: Maisey 1982, 1983; Lane, 2010.Entelognathus: Zhu et al. 2013.Falcatus: Lund 1985; Maisey 2007; specimens CM 35465, 37532Gladbachus: Heidtke & Krätschmer 2001; Heidtke 2009; Burrow & Turner 2013; specimen UMZC

2000.32.Guiyu: Zhu et al. 2009.Gyracanthides: Miles 1973a; Warren et al. 2000; Turner et al. 2005.Halimacanthodes: Burrow et al. 2012.Hamiltonichthys: Maisey 1989b.Helodus: Patterson 1965; Stahl 1999; specimens NHM P.6706, 8207, 8209, 8212, 8213.Homalacanthus: Gagnier 1996; Watson 1937; specimens FMNH PF4875; MM LL12452.Homalodontus: Mutter et al. 2007, 2008.Iniopera: Zangerl & Case 1973; Pradel et al. 2009, Pradel 2010; Pradel et al. 2010.Ischnacanthus; Miles 1973a; Watson 1937; specimens GM C3, 6, 149, 324; GM P298; MM L9522, 9431,

9432; MM STR0585; NMS (Powrie) 92.254, 258; UALVP 32401, 32405, 32414, 39060, 39075, 40478, 41491, 41861, 42201, 42215, 42660, 43245, 44048, 44049, 44091, 45014.

Kathemacanthus: Gagnier & Wilson 1996a; Hanke & Wilson 2010; specimens UALVP 32402, 42269, 43113.

Kawichthys: Pradel et al. 2011.Latviacanthus: Schultze & Zidek 1982.Lupopsyrus: Hanke & Davis 2012; Bernacsek & Dineley 1977; specimens NMC 22700B, 22700C, 22715,

22718, 22719, 22700D, 22700E, 22700F, 22701C, 22701D, 22716, 22717, 22720, 22745; UALVP 19260, 32420, 32442, 32456, 32458, 32474, 32476, 32480, 32482, 39065, 39067, 39079, 39080, 39081, 39082, 39121, 41493, 41629, 41632, 41665, 41931, 41939, 41945, 42000, 42002, 42008, 42012, 42013, 42027, 42046, 42061, 42113, 42142, 42150, 42173, 42208, 42274, 42518, 42524, 42529, 42530, 42533, 42538, 42453, 42454, 42455, 42544, 42597, 42605, 43064, 43091, 43092, 43094, 43095, 43256, 43409, 43456, 45154, 45155.

Mesacanthus: Miles 1973a; Watson 1937; specimens FMNH PF1439; GM C18, 288a &b; NMS (Powrie) 1891.92.275; UMZC GN1143.

Mimipiscis: Gardiner & Bartram 1977; Gardiner 1984; Choo 2011; Giles & Friedman 2014.Moythomasia: Gardiner & Bartram 1977; Gardiner 1984; Coates et al. 2017; specimen MV P222915.Nerepisacanthus: Burrow 2011; Burrow et al. 2014.Obtusacanthus: Hanke & Wilson 2004; specimen UALVP 41488.Onychoselache: Dick & Maisey 1980; Coates & Gess 2007.Orthacanthus: Heidtke 1982, 1999; Hotton 1952; Schaeffer 1981; Maisey 1983; Lane & Maisey 2009.Ozarcus and FMNH PF 13242: Maisey 2007; Pradel et al. 2014; Coates et al. 2017.Parexus: Watson 1937; Miles 1973a. specimens AMNH 1163, 7766; NMS Kinnaird 94; NMS (Peach)

1887.35.3a, 5e; NMS 1891 (Powrie) 92.183, 184, 186, 188, 194, 197, 207; NMS 1956.14.4.15; NMS 1977.46.3a & b.

118

Chapter III: Phoebodontid chondrichthyans of the Maider

Phoebodus: Newberry 1889; Ginter 1990; Ginter & Ivanov 1992, 1995; Ginter et al. 2002; Ginter et al. 2010; specimen PIMUZA/I 4656, PIMUZ A/I 4710, PIMUZ A/I 4712, PIMUZ A/I 4711, PIMUZ A/I 4713.

Poracanthodes: Denison 1979; Valiukevicius 1992. Promesacanthus: Hanke 2008; specimens UALVP 41672, 41859, 41860, 42652, 43027.Psarolepis: Yu 1998; Zhu & Schultze 1997; Zhu et al. 1999; Qu et al. 2013a.Ptomacanthus: Brazeau 2009, 2012; Denison 1979; Miles 1973a; specimens BM P.19999, 24919b.Pucapampella: Maisey 2001a; Maisey & Anderson 2001; Maisey & Lane 2010; Janvier & Maisey 2010.Raynerius: Giles et al. 2015b.Rhadinacanthus: Burrow et al. 2016.Squalus: Schaeffer 1981; Gans & Parsons 1964; Marinelli & Strenger 1959.Synechodus: Maisey 1985; NHM P.6135, 41675.Tamiobatis: Schaeffer 1981; Williams 1998; specimen FMNH PF5414.Tetanopsyrus: Gagnier & Wilson 1995; Gagnier et al. 1999; Hanke et al. 2001; specimens UALVP 32571,

38682, 39062, 39078, 42512, 43026, 43246, 44030, 43089.Thrinacodus: Turner 1982; Ginter 2000; Ginter & Sun 2007; Ginter & Turner 2010; Ginter et al. 2010;

Grogan & Lund 2008. Tribodus: Maisey & de Carvalho 1997; Lane 2010; Lane & Maisey 2009, 2012.Triodus: Solér-Gijon, R. & Hampe 1998; Hampe 2003; Heidtke et al. 2004.Tristychius: Dick1978; Coates & Gess 2007; Coates & Tietjen in press: specimens NMS 1972.27.455A,

1974.51.5A; HM V8299. Uraniacanthus: Bernacsek & Dineley 1977; Hanke & Davis 2008; Newman et al. 2012; Burrow et al.

2016; specimens UALVP 19259, 32448, 32469, 38679, 41669, 41857, 41858, 41862, 42095, 42095, 44046, 45366 to 45396.

Vernicomacanthus waynensis: Miles 1973a.Youngolepis: Chang & Yu 1981; Chang 1982, 1991, 2004.

4) Character listSkeletal tissues1 Tessellate calcifi ed cartilage: absent (0); present (1). Brazeau (2009); Coates & Sequeira (2001a,

b); Davis et al. (2012); Dean & Summers (2006); Dean et al. (2009); Grogan et al. (2012); Maisey (1984, 2001, 2013); Lund & Grogan (1997, 2004a, b); Seidel et al. (2016).

2 Perichondral bone: present (0); absent (1). Janvier (1996); Donoghue & Aldridge (2001); Brazeau (2009); Davis et al. (2012); Lund (1985); Coates et al. (1999).

3 Extensive endochondral ossifi cation: absent (0); present (1). Forey (1980); Gardiner (1984); Brazeau (2009); Davis et al. (2012).

4 Extensive calcifi ed cartilage: absent (0); present (1). This character refers to taxa where perichon-dral bone is absent but where cranial or postcranial skeletal parts consist of mineralized and therefore, more robust cartilage (Coates et al. 2018).

5 Dentine kind: mesodentine or semidentine (0); orthodentine (1). Donoghue et al. (2000); Brazeau (2009); Davis et al. (2012); Burrow et al. (2016). Orthodentine was coded as `non-applicable` in the data matrix of Grogan and Lund (2008). However, according to Ivanov (2000), the teeth of Thrinaco-dus contain orthodentine in the cusps and osteodentine in the base.

6 Pore canal network: absent (0); present (1). Lu et al. (2016).7 Acrodin tooth caps (enameloid cap restricted to crown apex): absent (0); present (1). Friedman

& Brazeau (2010); Zhu et al. (2013, 2009); Lu et al. (2016).

Squamation & related structures8 Trunk scales monocuspid (0); multicuspid (1). Revised after Davis et al. (2012); Burrow et al.

(2016). Scale growth differs among different groups of gnathostomes: scales of teleostomes (osteich-thyans and acanthodians) have a sustained growth whereas in non-teleostomes (chondrichthyans), the scales stop growing when reaching a determinate size (Nelson 1969; Reif 1985). However, in several Palaeozoic chondrichthyans, scales grow throughout their life (Nelson 1970; Zangerl 1981) and there-fore, limited scale growth is assumed to be a derived condition. In Phoebodus, we fi nd multicuspid scales, but their growth pattern is unkown thus far.

119

Chapter III: Phoebodontid chondrichthyans of the Maider

9 Scale growth concentric: absent (0); present (1). Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Burrow et al. (2016).

10 Peg-and-socket articulation: absent (0); present (1). Gardiner (1984); Coates (1999); Brazeau (2009); Davis et al. (2012).

11 Anterodorsal process on scale: absent (0); present (1). Zhu et al. (2009, 2013); Gardiner (1984); Coates (1999); Brazeau (2009); Davis et al. (2012).

12 Body scales with bulging base: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Burrow et al. (2016).

13 Body scales with fl attened base: absent (0); present (1). Brazeau (2009, 2012); Davis et al. (2012); Burrow et al. (2016).

14 Body scales with basal canal or open basal vascular cavity: absent (0); present (1). Placoid scales of both modern as well as early chondrichthyans (e.g. Akmonistion, Antarctilamna) are characterized by the presence of a basal canal (Reif 1978; Coates & Sequeira 2001a; Young 1982). Basal canals were identifi ed in disarticulated chondrichthyan scales such as Elegestolepis (Karatajūte-Talimaa 1992), Polymerolepis and Seretolepis (Hanke & Wilson 2010) as well as in a few acanthodian taxa such as Kathemacanthus, Tetanopsyrus (Hanke et al. 2001, fi g.2c), Lupopsyrus (Hanke and Davis 2012), and Ptomacanthus (Brazeau 2012, tentative identifi cation in fi g. 7D). Basal canals could not yet be identifi ed in the scales of Phoebodus.

15 Neck canal: absent (0) present (1). The presence of neck canals is a common feature in placoid scales, but neck canals were either found in scales of placoderms (Burrow & Turner 1998, 1999) and osteichthyans (Qu et al. 2013a, b).

16 Sensory line canal passes between or beneath scales (0); passes over scales and/or is partially

enclosed or surrounded by scales (1); perforates and passes through scales (2). Davis (2002); Friedman & Brazeau (2010); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014); Burrow et al. (2016). In Thrinacodus, the lateral line system of the mandibular region is enclosed by tesserate mineralized tissue.

17 Lepidotrichia or lepidotrichia-like scale alignment: present (0); absent (1). Davis et al. (2012).18 Epichordal lepidotrichia: absent (0); present (1). Zhu et al. (2009, 2013).19 Fringing fulcra: absent (0); present (1). Zhu et al. (2009, 2013); Coates (1999).20 Scute-like ridge scales (fulcra): absent (0); present (1). Giles et al. (2015c).

Cranial dermal skeleton21 Sclerotic ring: absent (0); present (1). Giles et al. (2015c); Qiao et al. (2016); Zhu et al. (2016);

Burrow et al. (2016). Sclerotic rings are present in early chondrichthyans such as Cladoselache (Lund 1986; Williams 2001; CMNH 8207 exhibits especially well preserved plates: pers. obs. MIC), Cobe-lodus (Zangerl & Case, 1976), Falcatus (Lund, 1985), Damocles (Lund, 1986), Ctenacanthus (Wil-liams, 2001), Gladbachus (Coates et al., 2018) and Iniopteryx (Zangerl & Case, 1973). No sclerotic ring is preserved in the available material of Phoebodus and Thrinacodus.

22 Number of sclerotic plates: four or less (0); more than four (1). Zhu et al. (2013, c170); Qiao et al. (2016, c.241); Zhu et al. (2016, c.239); Burrow et al. (2016).

23 Dermal ornamentation: smooth (0); parallel, vermiform ridges (1); concentric ridges (2); tuber-

culate (3). Giles et al. (2015c).24 Dermal skull roof includes large dermal plates (0); consists of undifferentiated plates, tesserae

or scales (1); naked or largely scale free (2). Forey (1980); Gardiner (1984); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).

25 Cranial tessera morphology: large interlocking plates (0); microsquamose, no larger than body

squamation (1). Brazeau (2009) through to Giles et al. (2015c).26 Anterior or mesial edge of nasal notched for anterior nostril: absent (0); present (1). Contra Zhu

et al. (2013), the anterior rim of the nasal in Cheirolepis is notched.27 Supraorbital: absent (0); present (1). Zhu et al. (2009, 2013).28 Large median bone contributes to posterior margin of skull roof: absent (0); present (1). Zhu et

al. (2016).29 Medial process of paranuchal wraps around posterolateral corners of nuchal plate: absent (0);

present (1); paranuchals precluded from nuchal by centrals (2); no median bone in posterior of

skull roof (3). Giles et al. (2015c).30 Pineal opening perforates dermal skull roof: present (0); absent (1). Davis et al. (2012); Giles et

120

Chapter III: Phoebodontid chondrichthyans of the Maider

al. (2015c).31 Consolidated cheek plates: absent (0); present (1). Davis (2002); Brazeau (2009); Davis et al.

(2012); Zhu et al. (2013); Burrow et al. (2016).32 Enlarged postorbital tessera separate from orbital series: absent (0); present (1). Brazeau (2009);

Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).33 Dermal intracranial joint: absent (0); present (1). Zhu et al. (2009, 2013)34 Foramina (similar to infradentary foramina) on cheek bones: absent (0); present (1). Zhu et al.

(2009, 2013).35 Preopercular bone: absent (0); present (1). Zhu et al. (2013).36 Maxilla expanded posteriorly: absent - splint shaped (0); present - cleaver shaped (1). Zhu et al.

(2009, 2013); Lu et al. (2016).37 Sensory line network preserved as open grooves (sulci) in dermal bones (0); sensory lines pass

through canals enclosed within dermal bones (1). (Davis 2002); Davis et al. (2012); Zhu et al. (2013).

38 Sensory canal or pit-line associated with maxilla: absent (0); present (1). Friedman (2007) 39 Jugal portion of infraorbital canal joins supramaxillary canal: present (0); absent (1). Brazeau

(2009), but see redefi nition in Davis et al. (2012); Zhu et al. (2013).40 Anterior pit line of skull roof: absent (0); present (1). Giles et al. (2015c).41 Spiracular opening in dermal skull roof bounded by bones carrying otic canal: absent (0); pres-

ent (1). Giles et al. (2015); Lu et al. (2016).42 Endolymphatic ducts open in dermal skull roof: present (0); absent (1). Janvier (1996); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013); Giles et al. (2015c). 43 Dermohyal (submarginal) ossifi cation: absent (0); present (1). 44 Dermohyal (submarginal) shape: broad plate that tapers towards its proximal end (0); narrow

plate (1). Brazeau’s (2009)45 Branchiostegal series: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).46 Opercular and subopercular bones: absent (0); present (1).

47 Branchiostegal plate series along ventral margin of lower jaw: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

48 Branchiostegal ossifi cations plate-like (0); narrow and ribbon-like (1); fi lamentous (2). Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Lu et al. (2016).

49 Branchiostegal ossifi cations ornamented (0); unornamented (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

50 Branchiostegals imbricated: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

51 Opercular cover of branchial chamber complete or partial (0); separate gill covers and gill slits

(1). Lund & Grogan (1997); Hanke & Wilson (2004); Davis et al. (2012); Zhu et al. (2013). Condition ´1` is likely a synapomorphy of recent elasmobranchs although opercular covers are not present in most Paleozoic chondrichtyans (Coates et al. 2017, see data matrix discussion in Coates et al. 2018). Opercular cover in holocephalans secondarily evolved (cf. Coates et al. 2017).

52 Gular plates: absent (0); present (1). Gardiner (1984); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

53 Size of lateral gular plates: extending most of length of the lower jaw (0); restricted to the anteri-

or third of the jaw (no longer than the width of three or four branchiostegals) (1). Coates (1999); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

Hyoid and gill arches54 Gill skeleton mostly beneath otico-occipital region (0); mostly posterior to occipital region (1).

Zangerl (1981); Lund & Grogan (1997); Stahl (1999). Except for holocephalans, the gill skeleton is mostly located posteriorly to the neurocranium in chondrichthyans. In acanthodians, gill skeletons are located either beneath or posterior to the occipital region of the braincase.

55 Perforate hyomandibula: absent (0); present (1). Zhu et al. (2009, 2013); Lu et al. (2016).56 Interhyal: absent (0); present (1). Davis et al. (2012); Zhu et al. (2013). 57 Ceratohyal smooth with posterior, lateral fossa: absent (0); present (1). Coates et al. (2018).

Characteristic feature in Recent and early elasmobranchs such as Egertonodus (Maisey 1983), Ortha-

121

Chapter III: Phoebodontid chondrichthyans of the Maider

canthus (Hotton 1952), Tristychius (Coates et al. 2018, supplementary Fig. 10e, f) and also Phoebo-dus (Fig. 1a-c).

58 Ceratohyal anteriorly blade-shaped: absent (0), present (1). The ceratohyal is a simple slightly curved, uniformely thick, rod-shaped cartilage in Recent and fossil chondrichthyans. Fossil examples are e.g. Akmonistion (Coates & Sequeira, 2001a), Denaea (Williams, 1985), Cobelodus (Zangerl & Case, 1976), Triodus (Heidtke et al., 2004) and Gladbachus (Coates et al., 2018). However, in Tristy-chius (pers. obs. MC) and Phoebodus, the ceratohyal exhibits a derived shape with the anteriormost portion laterally expanding. This is apparently not the condition in the phoebodont Thrinacodus, in which the ceratohyal shows a non-derived shape (Grogan & Lund, 2008, fi g. 10C). But because of the fl attened preservation of the Thrinacodus specimens, the character was coded as non-applicable.

59 Hypohyals: absent (0); present (1). Friedman & Brazeau (2010); Pradel et al. (2014). Present in osteichthyans and some Paleozoic chondrichthyans including Cobelodus, Akmonistion (Coates & Se-queira 2001a), Triodus (Heidtke et al. 2004; Hampe 2002, fi g. 18), Orthacanthus (Heidtke 1999, fi g. 7c) and possibly Falcatus (Lund 1985, fi g. 8b). Hypohyals were reconstructed for Thrinacodus gracia (Grogan & Lund 2008, fi g. 10C) while they are absent in Phoebodus (Fig. 1c), which corresponds to the condition in other chondrichthyans such as Gladbachus (Coates et al. 2018) and Tristychius (Coates & Tietjen 2018). In Acanthodes and stem group gnathostomes, hypohyals seem to be absent.

60 Basihyal absent, hyoid arch articulates directly with basibranchial (0); basihyal present (1).

Pradel et al. (2014); see also discussion in Carr et al. (2009); Brazeau et al. (2017). In osteichthyans, basihyals are rarely present and therefore, the hyoid arch articulates directly with basibranchials like in Acanthodes (Nelson 1968; Miles 1973b; Gardiner 1984). Basihyals are known from a variety of placoderms (Long 1997; Carr et al. 2009; Brazeau et al. 2017), and early and modern chondrichthyans (Zangerl &Case 1973, 1976; Maisey 1983; Didier 1995; see discussion in data matrix of Coates et al. 2018). In phoebodont chondrichthyans the basihyal is preserved in Phoebodus while it seems to be absent in Thrinacodus (Grogan & Lund 2008).

61 Separate supra- and infra-pharyngobranchials absent (0); present (1). Gardiner (1984); Pradel et al. (2014). Absent in many early gnathostome taxa such as Halimacanthodes, Acanthodes, Glad-bachus, Debeerius, Tristychius, hybodontids, and Triodus. Present in osteichthyans, but also in the chondrichthyan Ozarcus (Pradel et al. 2014).

62 Pharyngobranchials directed anteriorly (0); posteriorly (1). Pradel et al. (2014). Pharyngobran-chials are anteriorly directed in osteichthyans whereas in most chondrichthyans they are directed pos-teriorly. Among Paleozoic chondrichthyans posteriorly directed pharyngobranchials are known from e.g., Orthacanthus, Triodus, Debeerius, Tristychius and Falcatus (Coates et al. 2018, Lund 1985, fi g. 6). As exceptions, Gladbachus (Coates et al. 2018) and Ozarcus (Pradel et al. 2014) exhibit anteriorly directed pharyngobranchial elements. Pharyngobranchials are not known from Phoebodus yet.

63 Posteriormost branchial arch bears epibranchial unit: absent (0); present (1). Coates et al. (2018). Absent in osteichthyans; present in chondrichthyans, Gladbachus and Acanthodes (Davis et al. 2012; Pradel et al. 2014).

64 Epibranchials bear posterior fl ange: absent (0); present (1). Coates et al. (2018). Present in Acan-thodes (Coates et al. 2018, supplementary Fig. 9di), Gladbachus (Coates et al. 2018, supplementary Fig. 9dii), Halimacanthus (Burrow et al. 2012) and Ozarcus (Pradel et al. 2014).

65 Hypobranchials directed anteriorly (0); hypobranchials of second and more posterior gill arches

directed posteriorly (1). Coates et al. (2018). Hypobranchials are common in early osteichthyans and chondrichthyans but also in Acanthodes . Posteriorly directed: crown-chondrichthyans, xenacan-thids (Hampe 2002; Heidtke et al. 2004) and hybodontids. Anteriorly directed: Ozarcus and Falcatus (Coates et al. 2018).

Dentition & tooth-bearing bones and cartilages66 Oral dermal tubercles borne on jaw cartilages: absent (0); present (1). Hanke & Wilson (2004);

Brazeau (229); Davis et al. (2012); Zhu et al. (2013). 67 Pharyngeal teeth or denticles: absent (0); present (1). Commen feature in most early gnathostomes

except for placoderms. In early chondrichthyans: often small whorls on a fused base (Zangerl & Case 1976; Coates & Sequeira 2001a). Other shapes/arrangements of pharyngeal teeth are present in the hybodontid Hamiltonichthys (Maisey 1989) and Tribodus (Lane & Maisey 2012, Figs 4.1, 5). Disar-ticulated specimens are preserved in Phoebodus.

68 Tooth families/whorls: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau

122

Chapter III: Phoebodontid chondrichthyans of the Maider

(2009); Davis et al. (2012); Zhu et al. (2013).69 Bases of tooth families/whorls: single, continuous plate (0); some or all whorls consist of sepa-

rate tooth units (1). Adjusted by Coates et al. (2018) from Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Giles et al. (2015).

70 Lingual torus: absent (0); present (1). After Ginter et al. 2010; Coates et al. (2018). Present in most Palaeozoic chondrichthyans, exception: holocephalans with tooth plates.

71 Basolabial shelf: absent (0); present (1). After Ginter et al. (2010): The basolabial shelf at the tooth base articulates with the tooth crown of the overlying tooth of the same tooth family. Common feature in Palaeozoic chondrichthyans.

72 Tooth families/whorls restricted to symphysial region (0); distributed along jaw margin (1). Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013). Character score ´1` is likely a synapomorphic condition of chondrichthyans (Tucker and Fraser 2014, Coates et al. 2018).

73 Number of tooth families/whorls per jaw ramus: 15 or fewer (0); 20 or more (1). Coates et al. (2018). Character not applicable in Phoebodus because dentition is mostly disarticulated and/or not complete.

74 Toothplates absent (0); present (1). Follows defi nition of Coates et al. (2018): tooth plates are de-fi ned by fused adjacent tooth families.

75 Toothplate complement restricted to two pairs in the upper jaw and a single pair in the lower

jaw: absent (0); present (1). After Patterson (1965); Coates et al. (2018).76 Mandibular teeth fused to dermal plates on biting surfaces of jaw cartilages: absent (0); present

(1). Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013). 77 Dermal plates on biting surface of jaw cartilages: absent (0); present (1). Brazeau (2009); Davis

et al. (2012); Zhu et al. (2013); Giles et al. (2015c).78 Gnathal plates mesial to and/or above (or below) jaw cartilage: absent (0); present (1). Zhu et al.

(2016).79 Maxilla and premaxilla sensu stricto (upper gnathal plates lateral to jaw cartilage without pala-

tal lamina): absent (0); present (1). Zhu et al. (2016).80 Dentary bone encloses mandibular sensory canal: absent (0); present (1). Gardiner (1984) and

references therein; Zhu et al. (2009, 2013).81 Infradentary foramen and groove, series: absent (0); present (1). Zhu et al. (2010).82 Tooth-bearing median rostral: absent (0); present (1). Zhu et al. (2009, 2013).83 Median dermal bone of palate (parasphenoid): absent (0); present (1). Gardiner (1984); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013).84 Denticulated fi eld of parasphenoid: without spiracular groove (0); with spiracular groove (1).

Friedman (2007); Zhu et al. (2009, 2013).85 Denticle fi eld of parasphenoid with multifi d anterior margin: absent (0); present (1). Friedman

(2007); Zhu et al. (2009, 2013); Lu et al. (2016).

Mandibular arch86 Large otic process of the palatoquadrate: absent (0); present (1). Coates & Sequeira (2001a);

Davis (2002); Brazeau (2009); Zhu et al. (2009, 2013). In Paleozoic chondrichthyans, the palatoquad-rate is usually cleaver-shaped with a dorsoventrally large otic process. Examples are xenacanthids (Schaeffer 1981), symmoriiforms (Coates and Sequeira, 2001a, Zangerl 1981) and cladoselachians (Zangerl 1981). The otic process of Phoebodus shows a derived short shape (Fig. 1a-c). This contrasts the condition in Thrinacodus, in which the palatoquadrate appears to be higher (Grogan & Lund 2008, fi g. 10B). In hybodontids, the otic process is short but the quadrate expands laterally to form a deep adductor fossa (Maisey 1982).

87 Oblique ridge or groove along medial face of palatoquadrate: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Lu et al. (2016). Present in Acanthodes and chondrich-thyans such as Gladbachus and Orthacanthus.

88 Fenestration of palatoquadrate at basipterygoid articulation: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Lu et al. (2016).

89 Perforate or fenestrate anterodorsal (metapterygoid) portion of palatoquadrate: absent (0);

present (1). Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).90 Articulation surface of the palatoquadrate with the postorbital process directed anteriorly (0);

laterally (1); dorsally (2). Coates et al. (2017). Character varies among early gnathostomes and even

123

Chapter III: Phoebodontid chondrichthyans of the Maider

within the chondrichthyans: e.g. anteriorly in Acanthodes, Orthacanthus, Tamiobatis and Phoebodus; laterally (or anterolaterally) in Cobelodus and Akmonistion; dorsally in Tristychius.

91 Palatoquadrate fused to the neurocranium: absent (0); present (1). Coates et al. (2017).92 Pronounced dorsal process on Meckelian bone or cartilage: absent (0); present (1). Davis (2002);

Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016). 93 Mandibular mesial process: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et

al. (2013); Burrow et al. (2016). Synonyms of the mandibular mesial process are mandibular knob, preglenoid articular process, or mandibular condyle. It describes the auxiliary articular facet of the double jaw articulation in chondrichthyans (Hotton 1952; Maisey 1989a; Lane & Maisey 2012).

94 Jaw articulation located on rearmost extremity of mandible: absent (0); present (1). Davis et al. (2012); Zhu et al. (2013).

95 Dental sulcus (trough) adjacent to oral rim on Meckel’s cartilage and palatoquadrate: absent

(0); present (1). Coates et al. (2017). Characteristic feature of chondrichthyans, but absent in Glad-bachus as well as in holocephalans having toothplates. This character is not present in Phoebodus.

96 Scalloped oral margin on Meckel’s cartilage and palatoquadrate: absent (0); present (1). Coates et al. (2017). Characteristic of some symmoriiform chondrichthyans such as Akmonistion, Ozarcus, and Cladoselache, but also present in Helodus (pers. obs. MIC).

97 Mandibular symphysis fused: absent (0); present (1). Coates et al. (2017).

Neurocranium98 Internasal vacuities: absent (0); present (1). Lu et al. (2016). 99 Precerebral fontanelle: absent (0); present (1). Schaeffer (1981); Lund & Grogan (1997); Coates &

Sequeira (1998, 2001a, b); Maisey (2001a); Brazeau (2009); Pradel et al. (2011) Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).

100 Space for forebrain and (at least) proximal portion of olfactory tracts narrow and elongate,

extending between orbits: absent (0); present (1). Coates et al. (2017).101 Prominent, pre-orbital, rostral expansion of the neurocranium: present (0); absent (1). Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013). Present in chimaeroids (Giles et al. 2015c).102 Rostral bar: absent (0); present (1). Adapted from Maisey (1985); Coates et al. (2017). 103 Internasal groove absent (0); present (1). Coates et al. (2017); present in Iniopera and Dwykasela-

chus (Pradel 2010).104 Orbitonasal lamina dorsoventrally deep: absent (0); present (1). Patterson (1965); Davis et al.

(2012); Zhu et al. (2013); Coates et al. (2017). Present in chimaeroids and some Palaeozoic holoceph-alans including Debeerius, Chondrenchelys, and Helodus (Coates et al. 2018).

105 Palatobasal (or orbital) articulation posterior to the optic foramen (0); anterior to the optic

foramen, grooved, and overlapped by process or fl ange of palatoquadrate (1); anterior to optic

foramen, smooth, and overlaps or fl anks articular surface on palatoquadrate (2). Adapted by Coates et al. (2018) from Pradel et al. (2011, character 26), Coates et al. (2017, character 71) and Maisey (2005, p.61)

106 Trochlear nerve foramen anterior to optic nerve foramen: absent (0); present (1). Coates & Se-queira (2001). Characteristic in hybodontids, absent in Tristychius (Coates & Tietjen 2018).

107 Supraorbital shelf broad with convex lateral margin: absent (0); present (1). Coates & Sequeira (1998); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

108 Orbit directed mostly laterally and free of fl anking endocranial cartilage or bone: absent (0);

present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Coates et al. 2018). 109 Interorbital space broad (0); narrow (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013);

Coates et al. (2017).110 Optic pedicel: absent (0); present (1). Dupret et al. (2014); Zhu et al. (2009, 2013); Coates et al.

(2017).111 Ophthalmic foramen in anterodorsal extremity of orbit communicates with cranial interior:

absent (0); present (1). Coates et al. (2017).112 Extended prehypophysial portion of sphenoid: absent (0); present (1). Brazeau (2009); Davis et

al. (2012); Zhu et al. (2013).113 Canal for efferent pseudobranchial artery within basicranial cartilage: absent (0); present (1).

Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).114 Entrance of internal carotids: through separate openings fl anking the hypophyseal opening or

124

Chapter III: Phoebodontid chondrichthyans of the Maider

recess (0); through a common opening at the central midline of the basicranium (1). Schaeffer (1981); Coates & Sequeira (1998); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

115 Internal carotids: entering single or paired openings in the basicranium from a posterolateral

angle (0); entering basicranial opening(s) head-on from an extreme, lateral angle (1); absent (2). Coates et al. (2017).

116 Ascending basisphenoid pillar pierced by common internal carotid: absent (0); present (1). Miles (1973b); Brazeau (2009); Friedman & Brazeau (2010); Davis et al. (2012); Zhu et al. (2013).

117 Spiracular groove on basicranial surface: absent (0); present (1). Davis et al. (2012); Zhu et al. (2013).

118 Spiracular groove on lateral or transverse wall of jugular canal: absent (0); present (1). Davis et al. (2012); Zhu et al. (2013).

119 Spiracular groove open (0); enclosed by spiracular bar or canal (1). Lu et al. (2016), Coates et al. (2018).

120 Orbit larger than otic capsule: absent (0); present (1). Lund & Grogan (1997); Coates et al. (2017).121 Postorbital process and arcade: absent (0); present (1). Pradel et al. (2011); see also Maisey (2007)

and Coates et al. (2017). Character absent in crown group elasmobranchs (Coates et al. 2018).122 Postorbital process and arcade short and deep - width not more than maximum braincase width

(excluding arcade) (0); process and arcade wide - width exceeds maximum width of braincase,

and anteroposteriorly narrow (1); process and arcade massive (2); arcade forms postorbital

pillar (3). Coates et al. (2017). 123 Postorbital process downturned, with anhedral angle relative to basicranium: absent (0); pres-

ent (1). Present in hybodontids, Acronemus (Maisey 2011) and Tristychius (Dick 1978; Coates & Tietjen 2018).

124 Jugular canal diameter small (0); large (1); canal absent (2). Pradel et al. (2011); see Coates et al. (2018) for defi nition of small and large canals.

125 Canal, likely for trigeminal nerve (V) mandibular ramus, passes through the postorbital process

from proximal dorsal entry to distal and ventral exit: absent (0); present (1). Present in early chondrichthyans such as Cladodoides (Maisey, 2005), Dwykaselachus (Coates et al., 2017), Ortha-canthus, Tamiobatis and Pucapampella. In the latter two taxa, the canal was initially interpreted as the branch of the palatine nerve (Schaeffer 1981; Maisey 2001) but later reinterpreted by Coates et al. (2018). Also in Acanthodes the canal was reinterpreted (Coates et al. 2018) which was formerly described as the canal for the middle cerebral vein and a branch of the lateral line nerve (Davis et al. 2012). No such canal is evident in early actinopterygians (Gardiner 1984), Janusiscus, or placoderms.

126 Postorbital process expanded anteroposteriorly: absent (0); present (1). Generally a characteristic feature of hybodontids, but absent in Tristychius (Coates et al. 2018).

127 Postorbital process articulates with palatoquadrate: absent (0); present (1). Schaeffer (1981); Coates & Sequeira (1998); Maisey (2001a); Pradel et al. (2011); Davis et al. (2012); Zhu et al. (2013). Archaeostyly (Maisey 2008; here corresponding to character state ´1`) is a characteristic feature of early chondrichthyans and some acanthodians such as Acanthodes and Promesacanthus (Coates et al. 2018). In the neoselachian Synechodus, the archaeostylic condition secondarily evolved (Maisey 1985).

128 Trigemino-facial recess: absent (0); present (1). Goodrich (1930); Gardiner (1984 and references therein); Pradel (2010); Pradel et al. (2011); Davis et al. (2012).

129 Jugular canal long, extends throughout most of otic capsule wall posterior to the postorbital

process (0); short and/or groove present on exterior of otic wall (1); absent, path of jugular re-

moved from otic wall (2). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Giles et al. (2015c); Coates et al. (2017).

130 C-bout notch separates postorbital process from supraotic shelf: absent (0); present (1). Charac-teristic feature of Tristychius, present in Acronemus (Maisey 2011).

131 Postorbital fossa: absent (0); present (1). Zhu et al. (2013).132 Hyoid ramus of facial nerve (N. VII) exits through posterior jugular opening: absent (0); pres-

ent (1). Friedman (2007); Brazeau (2009); Friedman & Brazeau (2010); Davis et al. (2012); Zhu et al. (2013).

133 Periotic process: absent (0); present (1). Maisey (2007); Coates et al. (2017).134 Articulation facet for hyomandibula: single-headed (0), double-headed (1). Zhu et al. (2009,

2013).

125

Chapter III: Phoebodontid chondrichthyans of the Maider

135 Relative position of jugular groove and hyomandibular articulation: hyomandibula dorsal or

same level (i.e. on bridge) (0); jugular vein passing dorsal or lateral to hyomandibula (1). Brazeau & de Winter (2015).

136 Transverse otic process: absent (0); present (1). Lu et al. (2016); Giles et al. (2016) 137 Craniospinal process: absent (0); present (1). Giles et al. (2015); Lu et al. (2016). 138 Lateral otic process: absent (0); present (1). Schaeffer (1981); Coates & Sequeira (1998); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013). The lateral otic process projects far posteriorly from the otic region and it connects the hyomandibula to the braincase (Schaeffer 1981; Coates & Sequeira 1998). Such a process is well-known from Orthacanthus and Tamiobatis. The character is currently coded as ´0` in Akmonistion, because the “short, posterolateral angle” of the otic differs reasonably in shape from the lateral otic process in Orthacanthus and Tamiobatis (Coates et al., 2018). In Clado-doides (Maisey 2005) as well as in Phoebodus, lateral projections from the otic capsular wall are completely absent.

139 Hyomandibula articulates with neurocranium beneath otic shelf: absent (0); present (1).

140 Sub-otic occipital fossa: absent (0); present (1). Coates et al. (2017, 2018). See Schaeffer (1981; p. 15, fi g. 6, occipital view): concavity underneath the lateral otic process. The feature is present in Orthacanthus and Tamiobatis (Schaeffer 1981), but not in Cladodoides which has a similar braincase (Maisey 2005). For Phoebodus, the character was coded as inapplicable but it is most probably absent.

141 Postotic process: absent (0); present (1). Pradel et al. (2011); Coates et al. (2017).142 Otic capsule extends posterolaterally relative to occipital arch: absent (0); present (1). Maisey

(1985).143 Otic capsules: widely separated (0); approaching dorsal midline (1). Coates et al. (2017).144 Otic capsules project anteriorly between postorbital processes: absent (0); present (1). Present

in neoselachians (Maisey 1983) and probably in some early elasmobranchs, e.g., Acronemus (Maisey 2011).

145 Endocranial roof anterior to otic capsules dome-like, smoothly convex dorsally and anteriorly:

absent (0); present (1). Coates et al. (2017).146 Roof of skeletal cavity for cerebellum and mesencephalon signifi cantly higher than dorsal-most

level of semicircular canals: absent (0); present (1). Coates et al. (2017).147 Roof of the endocranial space for telencephalon and olfactory tracts offset ventrally relative to

level of mesencephalon: absent (0); present (1). Coates et al. (2017).148 Labyrinth cavity separated from the main neurocranial cavity by a cartilaginous or ossifi ed

capsular wall (0); skeletal medial capsular wall absent (1). Pradel et al. (2011); Davis et al. (2012); Zhu et al. (2013).

149 Double octaval nerve foramena in chondrifi ed mesial wall of otic capsule: absent (0); present

(1). Present in Tribodus and Egertonodus (Lane 2010); absent in chondrichthyans exhibiting a medial capsular wall (e.g Tristychius; Coates & Tietjen 2018).

150 External (horizontal) semicircular canal joins the vestibular region dorsal to posterior ampulla

(0); joins level with posterior ampulla (1). Davis et al. (2012); Zhu et al. (2013).151 Angle of external semicircular canal: in lateral view, straight line projected through canal in-

tersects anterior ampulla, external ampullae, and base of foramen magnum: absent (0); present

(1). Coates et al. (2017).152 Left and right external semicircular canals approach or meet the posterodorsal midine of the

hindbrain roof: absent (0); present (1). Coates et al. (2017).153 Preampullary portion of posterior semicircular canal absent (0); present (1). Coates et al. (2017).

Known from crown chondrichthyans (Daniel 1922; Maisey 2001b; Maisey & Lane 2010).154 Crus commune connecting anterior and posterior semicircular canals present (0); absent (1).

Coates et al. (2017). A crus commune is present in most early chondrichthyan groups (e.g. Coates et al. 2017, Maisey 2005, 2007, Schaeffer 1981). However, some hybodontids show a derived condition (posterior and anterior semicircular canals are separated from each other) such as in modern elasmo-branchs (Daniel 1922, Maisey 2001b, Maisey and Lane 2010, Pradel et al. 2011).

155 Sinus superior: absent or indistinguishable from union of anterior and posterior canals with

saccular chamber (0); present, elongate and nearly vertical (1). Davis et al. (2012); Zhu et al. (2013).

156 Lateral cranial canal: absent (0); present (1). Zhu et al. (2009, 2013); Lu et al. (2016). Character is present in early actinopterygians (Gardiner 1984; Coates 1998) and a putative stem osteichthyan

126

Chapter III: Phoebodontid chondrichthyans of the Maider

(Basden et al. 2000). 157 Endolymphatic ducts: posteriodorsally angled tubes (0); tubes oriented vertically through endo-

lymphatic fossa/posterior dorsal fontanelle (1). Schaeffer (1981); Coates & Sequeira (1998, 2001); Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

158 Posterior dorsal fontanelle connected to persistent otico-occipital fi ssure (0); posterior tectum

separates fontanelle from fi ssure (1). Schaeffer (1981); Coates & Sequeira (1998); Pradel et al. (2011).

159 Subcircular endolymphatic foramen: absent (0); present (1). Pradel et al. (2015), Coates et al. 2017. Character was renamed from subcircular endolymphatic fossa to subcircular endolymphatic foramen by Coates et al. (2017). It was suggested as a holocephalan synapomorphy (Maisey & Lane 2010).

160 External opening for endolymphatic ducts anterior to crus commune: absent (0); present (1). Coates et al. (2017).

161 Supraotic shelf broad: absent (0); present (1). Present in Tristychius and Acronemus (Maisey 2011).162 Dorsal otic ridge: absent (0); present (1). Coates & Sequeira (1998, 2001); Maisey (2001); Davis

(2002); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).163 Dorsal otic ridge forms a crest posteriorly: absent (0); present (1). Coates & Sequeira (1998,

2001); Pradel et al. (2011).164 Endolymphatic fossa: absent (0); present (1). Pradel et al. (2011). 165 Endolymphatic fossa elongate (slot-shaped), dividing dorsal otic ridge along midline: absent (0);

present (1). Coates et al. (2017). 166 Perilymphatic fenestra within the endolymphatic fossa: absent (0); present (1). Pradel et al.

(2011); Coates et al. (2017).167 Ventral cranial fi ssure: absent (0); present (1). Janvier (1996); Coates & Sequeira (2001); Maisey

(2001); Davis (2002); Brazeau (2009); Pradel et al. (2011); Davis et al. (2012); Zhu et al. (2013).168 Endoskeletal intracranial joint: absent (0); present (1). Janvier (1996); Davis et al. (2012); Zhu et

al. (2013).169 Metotic (otic-occipital) fi ssure: absent (0); present (1). Schaeffer (1981); Janvier (1996); Coates

& Sequeira (1998); Maisey (2001); Davis (2002); Brazeau (2009); Pradel et al. (2011); Davis et al. (2012); Zhu et al. (2013).

170 Vestibular fontanelle: absent (0); present (1). Brazeau (2009); Friedman & Brazeau (2010). Davis et al. (2012); Zhu et al. (2013).

171 Hypotic lamina: absent (0); present (1). Schaeffer (1981); Maisey (1984, 2001); Brazeau (2009); Pradel et al. (2011, 2013); Davis et al. (2012); Zhu et al. (2013); Coates et al. (2017).

172 Glossopharyngeal nerve path: directed laterally, across fl oor of the saccular chamber and exits

via foramen in side wall of the otic capsule (0); directed posteriorly, and exits through metotic

fi ssure or foramen in posteroventral wall of otic capsule (1); exits laterally through a canal con-

tained ventrally (fl oored) by the hypotic lamina (2); exits through a foramen anterior to the pos-

terior ampulla (3). Coates et al. (2017), adapted from Schaeffer (1981); Coates & Sequeira (1998, 2001); Brazeau (2009): Davis et al. (2012); Zhu et al. (2013); Pradel et al. (2011, 2013).

173 Glossopharyngeal and vagus nerves share common exit from neurocranium: absent (0); present

(1). Uniquely present in hybodontids such as Egertonodus and Tribodus.174 Basicranial morphology: platybasic (0); tropibasic (1). Brazeau (2009); Pradel et al. (2011); Davis

et al. (2012); Zhu et al. (2013). Defi nition of tropibasic versus platybasic: see Maisey (2007) and Pradel et al (2011).

175 Channel for dorsal aorta and/or lateral dorsal aortae passes through basicranium (0): exter-

nal to basicranium (1). Schaeffer (1981); Coates & Sequeira (1998); Brazeau (2009); Pradel et al. (2011); Brazeau & Friedman (2014); Coates et al. (2017).

176 Dorsal aorta divides into lateral dorsal aortae posterior to occipital level (0); anterior to level of

the occiput (1). Pradel et al. (2011); Giles et al. (2015); Coates et al. (2017).177 Ventral portion of occipital arch wedged between rear of otic capsules: absent (0); present (1).

Schaeffer (1981); Coates & Sequeira (1998); Maisey (2001a); Brazeau (2009); Pradel et al. (2011); Davis et al. (2012); Coates et al. (2017).

178 Dorsal portion of occipital arch wedged between otic capsules: absent (0); present (1). Schaeffer (1981); Coates & Sequeira (1998); Maisey (2001a); Brazeau (2009); Pradel et al. (2011); Davis et al. (2012); Coates et al. (2017).

127

Chapter III: Phoebodontid chondrichthyans of the Maider

179 Occipital crest anteroposteriorly elongate, and extends from the roof of the posterior tectum:

absent (0); present (1). The elongate condition (posterior tectum to the level of foramen magnum) is present in Callorhinchus and in the Palaeozoic chondrichthyans Kawichthys (Pradel et al. 2011, fi g. 5) and Iniopera (Pradel 2010, fi g. 5) (see Finarelli & Coates 2014). In contrast, Dwykaselachus, Akmonistion and FMNH PF 13242 (Maisey 2007, fi g. 7), show an anteroposteriorly short occipital crest (not exceeding the level of the anterior margin of the occipital fi ssure). The character is coded as ´absent` in Phoebodus, Orthacanthus, Triodus and hybodontids because their occipital crests extend from the occipital arch wedged between the otic capsules (Schaeffer 1981; Maisey 1982).

Axial and appendicular skeleton180 Calcifi ed vertebral centra: absent (0); present (1). Maisey (1985): biconcave calcifi ed vertebral

centra are absent in Palaeozoic chondrichthyans and therefore this character is suggested as a synapo-morphy of crown elasmobranchs (Coates et al. 2017).

181 Chordacentra: absent (0); present (1). Stahl (1999); Coates and Sequeira (2001); Coates et al. (2017). Known in Chondrenchelys (Finarelli & Coates 2014), Damocles (Lund 1986; CM 48760), Falcatus (Lund 1985) and in the caudalis of Akmonistion (Coates & Sequeira 2001).

182 Chordacentra polyspondylous and consist of narrow closely packed rings: absent (0); present

(1). Derived from Patterson (1965); Coates et al. (2017).183 Synarcual: absent (0); present (1). Stahl (1999); Brazeau (2009); Davis et al. (2012); Zhu et al.

(2013); Coates et al. (2017).184 Macromeric dermal pectoral girdle (0); micromeric or lacking dermal skeleton entirely (1).

Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).185 Macromeric dermal pectoral girdle composition: ventral and dorsal components (0); ventral

components only (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).186 Macromeric pectoral dermal skeleton forms complete ring around the trunk: present (0); ab-

sent (1). Goujet & Young (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).187 Median dorsal plate: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).188 Scapular process (dorsal) of shoulder endoskeleton: absent (0); present (1). Coates & Sequeira

(2001a); Zhu & Schultze (2001); Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).

189 Ventral margin of separate scapular ossifi cation: horizontal (0); deeply angled (1). Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

190 Cross sectional shape of scapular process: fl attened or strongly ovate (0); subcircular (1). Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).

191 Flange on trailing edge of scapulocoracoid: absent (0); present (1). Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).

192 Scapular process with posterodorsal process: absent (0); present (1). Coates & Sequeira (2001a); Davis et al. (2012); Zhu et al. (2013).

193 Mineralisation of internal surface of scapular process: mineralised all around (0); un-min-

eralised on internal face forming a hemicylindrical cross-section. Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).

194 Coracoid process: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).195 Procoracoid mineralisation: absent (0); present (1). Davis (2002); Hanke & Wilson (2004): Brazeau

(2009).196 Fin base articulation on scapulocoracoid: stenobasal, deeper than wide (0); eurybasal, wider

than deep (1). Lu et al. (2016).197 Pectoral fi n articulation monobasal (0); dibasal (1); three or more basals (2).

198 Metapterygium pectinate subtriangular plate or bar supporting numerous (six or more) radials

along distal edge: absent (0); present (1). Present in symmoriiforms and Diplodoselache.199 Metapterygial whip: absent (0); present (1). Coates et al. (2017).200 Biserial pectoral fi n endoskeleton: absent (0); present (1). Lu et al. (2016).201 Propterygium perforated: absent (0); present (1). Rosen et al. (1981); Patterson (1982); Davis et

al. (2012); Zhu et al. (2013).202 Pelvic girdle with fused puboischiadic bar: absent (0); present (1). Maisey (1984); Coates & Se-

queira (2001a); Coates et al. (2017).203 Mixipterygial/mixopterygial claspers: absent (0), present (1). Coates & Sequeira (2001a,b);

128

Chapter III: Phoebodontid chondrichthyans of the Maider

Brazeau & Friedman (2014). 204 Pre-pelvic clasper or tenaculum: absent (0); present (1). After Patterson (1965); Coates et al.

(2017).205 Number of dorsal fi ns, if present: one (0); two (1); one, extending from pectoral to anal fi n level

(2). Coates & Sequeira (2001a); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).206 Brush complex of bilaterally distributed calcifi ed tubes fl anking or embedded in calcifi ed carti-

lage core: absent (0); present (1). Coates et al. (2017, 2018); description of Brush complex in Lund (1985) and Coates et al. (1998). The rod-like structure in Falcatus and the brush complex in Akmonis-tion are homologous (Maisey 2009; Coates et al. 2018)

207 Posterior or pelvic-level dorsal fi n with calcifi ed base plate: absent (0); present (1). Coates & Sequeira (2001a, b). Present in Tristychius, hybodontids, and “Ctenacanthus”. Character was coded with state ´1` for Phoebodus because the specimen shows remains of cartilage ventrally to the dorsal fi n spine.

208 Posterior dorsal fi n with delta-shaped cartilage: absent (0); present (1). Coates & Sequeira (2001a, b). Present in many symmoriid taxa; absent in Cladoselache.

209 Posterior or pelvic-level dorsal fi n shape, base approximately as broad as tall and not broader

than other median fi ns (0); base much longer than fi n height, substantially longer than other

median fi ns (1). Brazeau & deWinter (2015); Lu et al. (2017). 210 Anal fi n: absent (0); present (1). Coates & Sequeira (2001); Brazeau (2009); Davis et al. (2012);

Zhu et al. (2013).211 Anal fi n base narrow, posteriormost proximal segments radials broad: absent (0); present (1).

Heidtke (1999). Present in xenacanthids, exception: Diplodoselache. 212 Caudal radials restricted to axial lobe (0); extend beyond level of body wall and deep into hypo-

chordal lobe (1). Davis et al. (2012); Zhu et al. (2013). 213 Caudal neural and/or supraneural spines or radials short (0); long, expanded, and supporting

high aspect-ratio (lunate) tail with notochord extending to posterodorsal extremity (1); noto-

chord terminates pre-caudal extremity, neural and heamal radial lengths near symmetrical and

support epichordal and hypochordal lobes respectively (2). Coates & Sequeira (2001a, b).

Spines: fi ns, cranial and elsewhere214 Dorsal fi n spine or spines: absent (0); present (1). Zhu et al. (2001); Zhu & Yu (2002); Friedman

(2007); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Lu et al. (2016). 215 Dorsal fi n spine at anterior (pectoral level) location only: absent (0); present (1). Coates & Sequei-

ra (2001a); Ginter et al. (2010). This character has been coded inapplicable in taxa having a continu-ous dorsal fi n extending throughout trunk length (Coates et al. 2017, 2018).

216 Dorsal fi n spine cross section: horseshoe shaped (0); fl at sided, with rectangular profi le (1); sub-

circular (2). Hampe (2002); Brazeau & de Winter (2015).217 Anterior dorsal fi n spine leading edge concave in lateral view: absent (0); present (1). This char-

acter is present in chondrichthyan genera in which fi n spines form derived shapes such as brush com-plexes or hook-like extensions. Examples are mostly symmoriids such as Akmonistion, Falcatus and Damocles but also Physonemus, which is a taxon based on fi n spines (Lund 1985, 1986). However, such fi n spines are known from males only and they are probably absent in females (Lund 1985; Maisey 2009). Therefore, the usefulness of this character is still challenged (Coates et al. 2018).

218 Anal fi n spine: absent (0); present (1). Maisey (1986); Davis (2002); Brazeau (2009).219 Pectoral fi n spines: absent (0); present (1). Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu

et al. (2013).220 Pectoral fi n spine with denticles along posterior surface: absent (0); present (1). Burrow et al.

(2016).221 Prepectoral fi n spines: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013). Present in Doliodus (Maisey et al. 2017).222 Admedian pectoral spines absent (0); present (1). Burrow et al. (2016); see also description of

Doliodus pectoral girdle (Maisey et al. 2017).223 Median fi n spine insertion: shallow, not greatly deeper than dermal bones/ scales (0); deep (1).

Davis (2002); Hanke & Wilson (2004); Brazeau (2009). Davis et al. (2012); Zhu et al. (2013).224 Intermediate (pre-pelvic) fi n spines: absent (0); present (1). Davis (2002); Hanke & Wilson (2004);

Brazeau (2009); Davis et al. (2012); Zhu et al. (2013). Pre-pelvic spines are generally absent in early

129

Chapter III: Phoebodontid chondrichthyans of the Maider

and recent chondrichthyans. Doliodus is an exception (Maisey et al. 2017).225 Fin spines with ridges: absent (0); present (1). Davis (2002); Brazeau (2009); Davis et al. (2012);

Zhu et al. (2013).226 Fin spines with nodes: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau

(2009). Davis et al. (2012); Zhu et al. (2013).227 Fin spines (dorsal) with rows of large denticles: absent (0); on posterior surface (1); on lateral

surface (2). Maisey (1989b); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).228 Cephalic spines: absent (0); present (1). Maisey (1989); Coates et al. (2017)

5) ReferencesArratia, G. & Cloutier, R. in Devonian Fishes and Plants of Migua-

sha, Quebec, Canada (eds. Schultze, H.-P. & Cloutier, R.) 165-197 (Verlag Dr. Friedrich Pfeil, Munich, 1996).

Agassiz, L. J. R. Recherches sur les poissons fossiles. 3, viii+390+32 pp. Petitpierre, Neuchâtel et Soleure (1843B, 1937-1843).

Basden, A. M., Young, G. C., Coates, M. I. & Ritchie, A. The most primitive osteichthyan braincase? Nature 403, 185-188 (2000).

Bendix-Almgreen, S. E. The paired fi ns and shoulder girdle in Cladoselache, their morphology and phyletic signifi cance. Colloques Internationaux du Centre National de la Recherche Scientifi que 218, 111-123 (1975).

Bernacsek, G.M., & Dineley, D.L. New acanthodians from the De-lorme Formation (Lower Devonian) of N.W.T., Canada. Paleon-tographica Abt.A 158, 1-25 (1977).

Bonaparte, C. L. J. L. Iconografi a della fauna italica per le quatro classi degli animali vertebrati. Tomo III : Pesci. 266 pp. (Salvi-ucci), Roma (1838B).

Brazeau, M. D. The braincase and jaws of a Devonian ‘acanthodian’ and modern gnathostome origins. Nature 457, 305-308 (2009).

Brazeau, M. D. A revision of the anatomy of the early Devonian jawed vertebrate Ptomacanthus anglicus Miles. Palaeontology 55, 355-367 (2012).

Brazeau, M. D. & Friedman, M. The characters of Palaeozoic jawed vertebrates. Zoological Journal of the Linnean Society, 170, 779-821 (2014).

Brazeau, M. D. & de Winter, V. The hyoid arch and braincase anato-my of Acanthodes support chondrichthyan affi nity of ‘acantho-dians’. Proc. R. Soc. B 282: 20152210 (2015).

Brazeau, M. D., Friedman, M., Jerve, A., & Atwood, R. C. A three-dimensional placoderm (stem-group gnathostome) pha-ryngeal skeleton and its implications for primitive gnathostome pharyngeal architecture. Journal of Morphology. DOI: 10.1002/jmor.20706 (2017).

Burrow, C. J. A new lophosteiform (Osteichthyes) from the Lower Devonian of Australia. Geobios M. S. 19, 327-333 (1995).

Burrow, C. J. A partial articulated acanthodian from the Silurian of New Brunswick, Canada. Can. J. Earth Sci 48, 1329-1341 (2011).

Burrow, C. J., den Blaauwen, J., Newman, M. & Davidson, R. The diplacanthid fi shes (Acanthodii, Diplacanthiformes, Diplacan-thidae) from the Middle Devonian of Scotland. Palaeontologica Electronica 19, 1-83 (2016).

Burrow, C. J. & Rudkin, D. Oldest near-complete acanthodian: the fi rst vertebrate from the Silurian Bertie formation konser-vat-Lagerstätte, Ontario. PLoS ONE 9(8), DOI:10.1371/journal.pone.0104171 (2014).

Burrow, C. J., Trinajstic, K. & Long, J. First acanthodian from the Upper Devonian (Frasnian) Gogo Formation, Western Austra-lia. Historical Biology 24, DOI:10.1080/08912963.2012.660150 (2012).

Burrow, C. J. & Turner, S. Devonian placoderm scales from Aus-tralia. Journal of Vertebrate Paleontology 18, 677-695 (1998).

Burrow, C. J. & Turner, S. A review of placoderm scales, and their signifi cance in placoderm phylogeny. Journal of Vertebrate Pa-leontology 19, 204-219 (1999).

Burrow, C. J. & Turner, S. Scale structure of the putative chondrich-thyan Gladbachus adentatus Heidtke & Krätschmer, 2001 from the Middle Devonian Rheinisches Schiefergebirge, Germany. Historical Biology 25, 385-390 (2013).

Carr, R. K., Johanson, Z. & Ritchie, A. The phyllolepid placoderm Cowralepis mclachlani: insights into the evolution of feed-ing mechanisms in jawed vertebrates. J. Morph 270, 775-804 (2009).

Chang, M. M. The braincase of Youngolepis, a Lower Devonian

crossopterygian from Yunnan, south-western China. Doctor-al dissertation, Department of Geology, Stockholm University (1982).

Chang, M. M. Head exoskeleton and shoulder girdle of Youngole-pis. In Early vertebrates and related problems of evolutionary biology, M. M. Chang, Y. H. Liu & G. R. Zhang, eds. (Beijing: Science Press), pp. 355-378 (1991).

Chang, M. M. Synapomorphies and scenarios - more characters of Youngolepis betraying its affi nity to the Dipnoi. In Recent Ad-vances in the Origin and Early Radiation of Vertebrates, G. Ar-ratia, M. V. H. Wilson & R. Cloutier, eds. (München: Verlag Dr. Friedrich Pfeil), pp. 665-686 (2004).

Chang, M.-M. & Yu, X.-B. A new crossopterygian, Youngolepis praecursor, gen. et sp. nov., from Lower Devonian of E. Yun-nan, China. Sci. Sin. 24, 89-97 (1981).

Choo, B. Revision of the actinopterygian genus Mimipiscis (= Mimia) from the Upper Devonian Gogo Formation of West-ern Australia and the interrelationships of early Actinopterygii. Earth and Environmental Science Transactions of the Royal So-ciety of Edinburgh, 102: 77-104 (2011)

Coates, M. I. Actinopterygians from the Namurian of Bearsden, Scotland, with comments on the early evolution of actinoptery-gian neurocrania. Zool. J. Linn. Soc. 122, 27-59. (1998).

Coates, M.I., Finarelli, J.A., Sansom, I.J., Andreev, P.S., Criswell, K.E., Tietjen, K., Rivers, M.L., La Riviere, P.J. An early chon-drichthyan and the evolutionary assembly of a shark body plan. Proceedings of the Royal Society B 285: 20172418. (2018) http://dx.doi.org/10.1098/rspb.2017.2418

Coates, M. I., Gess, R. W., Finarelli, J. A., Criswell, K. E. & Tietjen, K. A symmoriiform chondrichthyan braincase and the origin of chimaeroid fi shes. Nature 541, 209-211 (2017).

Coates, M. I., Sansom, I. J. & Smith, M. M. Spines and tissues of ancient sharks. Nature 396, 729-730 (1998).

Coates, M. I. & Sequeira, S. E. K. The braincase of a primitive shark. Trans. R. Soc. Edinb. (Earth Sci.) 89, 63-85 (1998).

Coates, M. I. & Sequeira, S. E. K. A new stethacanthid chondrich-thyan from the Lower Carboniferous of Bearsden, Scotland. J. Vertebr. Paleontol. 21, 754-766 (2001a).

Coates, M. I. & Sequeira, S. E. K. in Major Events in Early Verte-brate Evolution (ed. Ahlberg, P. E.) 241-262 (Taylor and Fran-cis, 2001b).

Coates, M. I. & Tietjen, K. The neurocranium of the Lower Car-boniferous shark Tristychius arcuatus (Agassiz, 1837). Earth and Environmental Science Transactions of the Royal Society of Edinburgh (2018).

Cole, F. J. On the cranial nerves of Chimaera monstrosa (Linn.); with a discussion of the lateral line system and of the morphology of the chorda tympani. Trans. R. Soc. Edinb. 38, 631-680 (1896).

Daniel, J. F. The Elasmobranch Fishes (Univ. California Press, Berkeley, 1922).

Davis, S. P. Comparative anatomy and relationships of the acanthodi-an fi shes. Unpublished PhD thesis, Unv. London, 1-318. (2002).

Davis, S. P., Finarelli, J. A., & Coates, M. I. Acanthodes and shark-like conditions in the last common ancestor of modern gnatho-stomes. Nature 486, 247-250 (2012).

Dean, M. N. & Summers, A. P. Cartilage in the skeleton of cartilagi-nous fi shes. Zoology 109,164-168 (2006).

Dean, M. N., Mull, C. G., Gorb, S. N. & Summers, A. P. Ontogeny of the tessellated skeleton: insight form the skeletal growth of the round stingray Urobatis halleri. J. Anat. DOI:10.1111/j.1469-7580.2009.01116x (2009).

DeBeer, G. R. The Development of the Vertebrate Skull (Univ. Chi-cago, 1937).

De Beer, G. R. & Moy-Thomas, J. A. On the skull of Holocephali. Philos. Trans. R. Soc. London B. Biol. Sci. 224: 287-312 (1935).

130

Chapter III: Phoebodontid chondrichthyans of the Maider

Denison, R. in Handbook of Paleoichthyology Vol. 5 (ed. Schultze, H.-P.) (Gustav Fischer Verlag, Stuttgart, 1979).

Derycke, C. Microrestes de Sélaciens et autres Vertébrés du Dévo-nien supérieur du Maroc. Bulletin du Muséum national d’His-toire Naturelle, Section C, Sciences de la terre, paléontologie, géologie, minéralogie 14(1), 15-61 (1992).

Derycke, C. Paléobiodiversité des gnathostomes (chondrichthyens, acanthodiens et actinoptérygiens) du Dévonien du Maroc (NW Gondwana), in: Zouhri, S. (ed), Paléontologie des vertébrés du Maroc: état des connaissance, Mémoires de la Société Géolo-gique de France 180, p. 624 (2017).

Derycke, C., Olive, S., Groessens, E., & Goujet, D. Paleogeograph-ical and paleoecological constraints on Paleozoic vertebrates (chondrichthyans and placoderms) in the Ardenne Massif Shark radiations in the Famennian on both sides of the Palaeotethys. Palaeogeography, Palaeoclimatology, Palaeoecology 414, 61-67 (2014).

Derycke, C., Spalletta, C., Perri, M. C., & Corradini, C. Famennian chondrichthyan microremains from Morocco and Sardinia. Journal of Paleontology 82(5), 984-995 (2008).

Dennis, K. D. & Miles, R. S. A pachyosteomorph arthrodire from Gogo, Western Australia. Zoological Journal of the Linnean So-ciety 73, 213-258 (1981).

Dick, J. R. F. On the Carboniferous shark Tristychius arcuatus Agas-siz from Scotland. Trans. R. Soc. Edinb. 70, 63-109 (1978).

Dick, J. R. F. Diplodoselache woodi gen. et sp. nov., an early Car-boniferous shark from the Midland Valley of Scotland. Trans. R. Soc. Edinb. 72, 99-113 (1981).

Dick, J. R. F. & Maisey, J. G. The Scottish Lower Carboniferous shark Onychoselache traquairi. Palaeontology 23, 363-374 (1980).

Didier, D. A. Phylogenetic systematics of extant chimaeroid fi sh-es (Holocephali, Chimaeroidei). Am. Mus. Novit. 3119, 1-86 (1995).

Didier, D. A., Kemper, J. M. & Ebert, D. A. in Biology of Sharks and Their Relatives (eds Carrier, J. C., Musick, J. & Heithaus, M. R.) 97-122 (CRC Press, 2012).

Didier, D. A., Stahl, B. J. & Zangerl R. Development and growth of compound tooth plates in Callorhinchus milii (Chondrichthyes, Holocephali). Journal of Morphology 222, 73-89 (1994).

Donoghue, P.C.J., & Aldridge, R. J. in Major events in early verte-brate evolution: palaeontology, phylogeny, genetics and devel-opment. (ed Ahlberg, P. E.) 85–105 (Taylor & Francis, 2001).

Donoghue, P. C. J., Forey, P. L., & Aldridge, R. J. Conodont affi nity and chordate phylogeny. Biol. Rev.75, 191-251 (2000).

Dupret, V., Sanchez, S., Goujet, D., Tafforeau, P. & Ahlberg, P. E. A primitive placoderm sheds light on the origin of the jawed vertebrate face. Nature 507, 500-503 (2014).

Eastman, C. R. Tamiobatis vetustus: a new form of fossil skate. American Journal of Science

4(4), 85-90 (1897A). Ebert, D. A. & Compagno, L. J. V.. Chlamydoselachus africana, a

new species of frilled shark from southern Africa (Chondrich-thyes, Hexanchiformes, Chlamydoselachidae). Zootaxa 2173, 1-18 (2009).

Finarelli, J. A. & Coates, M. I. First tooth-set outside the jaws in a vertebrate. Proceedings of the Royal Society of London Series B-Biological Sciences 279, 775-779 (2012).

Finarelli, J. A. & Coates, M. I. Chondrenchelys problematica (Tra-quair, 1888) redescribed: a Lower Carboniferous, eel-like ho-locephalan from Scotland. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 105, 1-25 (2014).

Forey, P. L. Latimeria: a paradoxical fi sh. Proc. R. Soc. London, Ser. B 208, 369-384 (1980).

Frey, L., Pohle, A., Rücklin, M. & Klug, C. Fossil-Lagerstätten and preservation of vertebrates and invertebrates from the Moroccan Devonian (eastern Anti-Atlas). Lethaia, XX (XX), XXX–XXX. (20XX)

Frey, L., Rücklin, M., Korn, D., & Klug, C. Late Devonian and Early Carboniferous alpha diversity, ecospace occupation, ver-tebrate assemblages and bio-events of southeastern Morocco. Palaeogeography, Palaeoclimatology, Palaeoecology 496, 1-17 (2018).

Friedman, M. Styloichthys as the oldest coelacanth: implications for early osteichthyan interrelationships. J. Syst. Palaeontol. 5, 289-343 (2007).

Friedman, M. & Brazeau, M. A reappraisal of the origin and basal radiation of the Osteichthyes. J. Vertebr. Paleontol. 30, 36-56 (2010).

Gans, C. & Parsons, T. S. A Photographic Atlas of Shark Anatomy (Academic Press, New York, 1964).

Gagnier, P. Y. in Devonian Fishes and Plants of Miguasha, Quebec, Canada. (eds Schultze, H. P. & Cloutier, R.) 149-163 (Freidrich Pfeil, 1996).

Gagnier, P. Y., Hanke, G. F. & Wilson, M. V. H. Tetanopsyrus lin-doei gen. et sp. nov., an Early Devonian acanthodian from the Northwest Territories, Canada. Acta Geologica Polonica 49, 81-96 (1999).

Gagnier, P. Y. & Wilson, M. V. H. New evidences on jaw bones and jaw articulations in acanthodians. Geobios 19 (1995).

Gagnier, P. Y. & Wilson, M. V. H. Early Devonian acanthodians from northern Canada. Palaeontology 39, 241-258 (1996a).

Gagnier P. Y. & Wilson M. V. H. An unusual acanthodian from Northern Canada: revision of Brochoadmones milesi. Modern Geology 20, 235-251 (1996b).

Gardiner, B. G. The relationships of the palaeoniscoid fi shes, a re-view based on new specimens of Mimia and Moythomasia from the Upper Devonian of Western Australia. Bull. Br. Mus. Nat. Hist. (Geol.) 37, 173-428 (1984).

Giles, S., Coates, M., Garwood, R. J., Brazeau, M. D., Atwood, R., Johanson, Z. & Friedman, M. Enodskeletal structure in Cher-olepis (Osteichthyes, Actinopterygii), an early ray-fi nned fi sh. Palaeontology 2015, DOI:10.1111/pala. 12182 (2015a).

Giles, S., Darras, L., Clément, G., Blieck, A. & Friedman, M. An ex-ceptionally preserved Late Devonian actinopterygian provides a new model for primitive cranial anatomy in ray-fi nned fi shes. Proc. R. Soc. B 282: 20151485 (2015b).

Giles, S., Friedman, M. Virtual reconstruction of endocast anatomy in early ray-fi nned fi shes (Osteichthyes, Actinopterygii). Jour-nal of Paleontology, 88(4), 636-651 (2014).

Giles, S., Friedman, M. & Brazeau, M. D. Osteichthyan-like cranial conditions in an Early Devonian stem gnathostome. Nature 520,

82-85 (2015c).Ginter, M. Late Famennian shark teeth from the Holy Cross Mts,

Central Poland. Acta Geologica Polonica 40, 69-81 (1990). Ginter, M. Late Famennian pelagic shark assemblages. Acta Geolog-

ica Polonica 50(2), 369-386 (2000).Ginter, M. Devonian sharks and the origin of Xenacanthiformes.

In: Arratia, G., Wilson, M. V. H. and Cloutier, R. (eds.), Recent advances in the origin and early radiation of vertebrates. p. 473-486. Friedrich Pfeil, München (2004).

Ginter, M., Hairapetian, V. & Klug, C. Famennian chondrichthyans from the shelves of North Gondwana. Acta Geologica Polonica 52(2), 169-215 (2002).

Ginter, M., Hampe, O. & Duffi n, C. J. Chondrichthyes: Paleozoic Elasmobranchii: teeth, in: Schultze, H. (Ed.), Handbook of Pa-leoichthyology, 3D, 168 p. (2010).

Ginter, M. & Ivanov, A. Devonian phoebodont shark teeth. Acta Pa-laeontologica Polonica 37(1), 55-75 (1992).

Ginter, M. & Ivanov, A. Middle/Late Devonian Phoebodont-based ichthyolith zonation. [Zonation ichthyologique du Dévonien moyen/supérieur fondée sur les Phoebodontes]. Geobios 19, 351-355 (1995).

Ginter, M. & Sun, Y. Chondrichthyan remains from the Lower Car-boniferous of Muhua, southern China. Acta Palaeontologica Polonica 52(4), 705-727 (2007).

Ginter, M. & Turner, S. The early Famennian recovery of pheobo-sont sharks. Acta Palaeontologica Polonica 49(2), p. 105-117 (1999).

Ginter, M. & Turner, S. The middle Paleozoic Selachian genus Thri-nacodus. Journal of Vertebrate Paleontology 30(6), 1666-1672, (2010), doi:10.1080/02724634.2010.520785.

Goodrich E. S. Studies on the structure and development of verte-brates (Univ. Chicago Press, 1930).

Goujet, D. & Young, G. C. Interrelationships of placoderms revisit-ed. Geobios Mem. Spec. 19, 89-95 (1995).

Goujet D, & Young G. C. in Recent Advances in the Origin and Early Radiation of Vertebrates, (eds Arratia, G., Wilson, M. V. H. & Cloutier, R.) 109-26 (Friedrich Pfeil, 2004).

Grogan, E. D. and Lund, R. Debeerius ellefseni (Fam. Nov., Gen. Nov., Sped. Nov.) an Autodiastylic Chondrichthyan From the Mississippian Bear Gulch Limestone of Montana (USA), the Relationships of the Chondrichthyes, and Comments on Gna-

131

Chapter III: Phoebodontid chondrichthyans of the Maider

thostome Evolution. J. Morphol. 243, 219-245 (2000).Grogan, E.D. & Lund, R. A basal elasmobranch, Thrinacoselache

gracia n. gen & sp., (Thrinacodontidae, new family) from the Bear Gulch Limestone, Serpukhovian of Montana, USA. Jour-nal of Vertebrate Paleontology 28(4), 970-988 (2008).

Grogan, E. D., Lund, R. & Greenfest-Allen, E. in Biology of Sharks and Their Relatives (eds Carrier, J. C., Musick, J. A. & Heithaus, M. R.) 3-29 (CRC Press, 2012).

Gross, W. Das Kopfskelett on Cladodus wildungensis Jaekel; 1. Teil. Endocranium und Palatoquadratum. Senckenbergiana 19, 80-107 (1937).

Gross, W. Das Kopfskelett on Cladodus wildungensis Jaekel; 2. Teil. Der Kieferbogen. Anhang: Protractodus vetusus Jaekel. Sen-ckenbergiana 20, 123-145 (1938).

Hairapetian, V. & Ginter, M. Famennian chondrichthyan remains from the Chahriseh section, central Iran. Acta Geologica Polon-ica 59(2), 173-200 (2009).

Hairapetian, V. & Ginter, M. Pelagic chondrichthyan microremains from the Upper Devonian of the Kale Sardar section, eastern Iran. Acta Geologica Polonica 60(3), 357-371 (2010).

Hampe, O. Revision of the Xenacanthida (Chondrichthyes: Elasmo-branchii) from the Carboniferous of the British Isles. Trans. R. Soc. Edinb. (Earth Sci.) 93, 191-237 (2003).

Hampe, O., Aboussalam, Z. S. & Becker, R. T. Omalodus teeth (Elasmobranchii: Omalodontida) from the northern Gondwana margin (middle Givetian: ansatus conodont Zone, Morocco), in: Arratia, G., Wilson, M. V. H., Cloutier, R. (Eds.), Recent ad-vances in the origin and early radiation of vertebrates, 487-504 (2004).

Hanke G. F. Promesacanthus eppleri n. gen., n. sp., a mesacanthid (Acanthodii, Acanthodiformes) from the Lower Devonian of northern Canada. Geodiversitas 30, 287-302 (2008).

Hanke, G. F. & Davis, S. P. Redescription of the acanthodian Gladio-branchus probaton Bernacsek & Dineley, 1977, and comments on diplacanthid relationships. Geodiversitas 30, 303-330 (2008).

Hanke, G. F. & Davis, S. P. A re-examination of Lupopsyrus pygmae-us Bernacsek & Dineley, 1977 (Pisces, Acanthodii). Geodiversi-tas 34, 469-487 (2012).

Hanke, G. F., Davis, S. P. & Wilson, M. V. H. A new species of the acanthodian genus Tetanopsyrus from Northern Canada, with comments on related taxa. J. Vert. Paleontol. 21, 740-753 (2001).

Hanke, G. F., & Wilson, M. V. H. in Recent Advances in the Origin and Early Radiation of Vertebrates. (eds Arratia, G., Wilson, M. V. H., & Cloutier, R.) 189–216 (Freidrich Pfeil, 2004).

Hanke, G. F. & Wilson, M. V. H. Anatomy of the Early Devonian Acanthodian Brochoadmones milesi based on nearly complete body fossils, with comments on the evolution and development of paired fi ns. J. Vert. Paleontol. 26, 526-537 (2006).

Hanke, G. F., & Wilson, M. V. H. in Morphology, Phylogeny and Paleobiogeography of Fossil Fishes. (eds Elliot, D.K., Maisey, J.G., Yu, X. & Miao, D.) 159-182 (Freidrich Pfeil, 2010).

Harris, J. E. The dorsal fi n spine of Cladoselache. Scientifi c Pub-lications of the Cleveland Museum of Natural History 8, 1-6 (1938a).

Harris, J. E. The neurocranium and jaws of Cladoselache. Scientif-ic Publications of the Cleveland Museum of Natural History 8, 7-12 (1938b).

Harris, J. E.. Diademodus hydei, a new fossil shark from the Cleve-land Shale. Proceedings of the Zoological Societey of London 120, 683-697 (1951).

Heidtke, U. H. J. Der Xenacanthide Orthacanthus senckenbergianus aus dem pfälzischen Rotliegenden (Unter-Perm). Pollichia 70, 65-86 (1982).

Heidtke, U. Studien über Acanthodes. 4. Acanthodes boyi n. sp., die dritte Art der Acanthodier (Acanthodii: Pisces) aus dem Rotlie-gend (Unterperm) des Saar-Nahe-Beckens (S-W-Deutschland. Paläont. Z. 67, 331-341 (1993).

Heidtke, U. H. J. Orthacanthus (Lebachacanthus) senckenbergianus Fritsch 1889 (Xenacanthida: Chondrichthyes): revision, organi-sation und phylogenie. Freiberger Forschungsheft 481, 63-106 (1999).

Heidtke, U. H. J. Gladbachus adentatus, die Geschichte des weltweit ältesten Hais – untersucht und beschriebenaus dem AK Geowis-senschaften. Pollichia Kurrier 25, 24-26 (2009).

Heidtke, U. H. J. Neue Erkenntnisse über Acanthodes bronni Agassiz 1833. Mitt. Pollichia 95, 1-14 (2011a).

Heidtke, U. H. J. Revision der unterpermischen Acanthodier (Acan-thodii: Pisces) des südwestdeutschen Saar-Nahe-Beckens. Mitt. Pollichia 95, 15-41 (2011b).

Heidtke, U. H. J. & Krätschmer K. Gladbachus adentatus nov. gen. et sp., ein primitiver Hai aus dem Oberen Givetium (Oberes Mit-teldevon) der Bergisch Gladbach – Paffrath-Mulde (Rheinisches Schiefergebirge). Mainzer geowiss. Mitt. 30, 105-122 (2001).

Heidtke, U. H. J., Schwind, C. Über die Organisation des Skelet-tes der Gattung Xenacanthus (Elasmobranchii: Xenacanthida) aus dem Unterperm des südwestdeutschen Saar-Nahe-Beckens. Neues Jahrbuch der Geologie und Paläontologie, Abhandlun-gen 231(1), 85–117 (2004).

Heidtke, U. H. J., Schwind, C. & Krätschmer K. Über die Organisa-tion des Skelettes und die verwandschaftlichen Beziehungen der Gattung Triodus Jordan 1849 (Elasmobranchii: Xenacanthida). Mainzer geowiss. Mitt. 32, 9-54 (2004).

Hotton, N. Jaws and teeth of American xenacanth sharks. Journal of Paleontology 26, 489-500 (1952).

Howard, L. E., Holmes, W. M., Ferrando, S., Maclaine, J. S., Kelsh, R. N., Ramsey, A., Abel R. L. & Cox P. L. J. Functional nasal morphology of chimaeroid fi shes. Journal of Morphology 274: 987-1009 (2013).

Huxley, T. A manual of the anatomy of vertebrated animals, 431pp. (D-Appleton and Co.), New York (1880B).

Janvier, P. Early Vertebrates (Oxford Univ. Press, 1996).Janvier, P. & Maisey, J. G. (2010) in Morphology, Phylogeny and

Paleobiogeography of Fossil Fishes. (eds Elliot, D.K., Maisey, J.G., Yu, X. & Miao, D.) 431-459 (Freidrich Pfeil, 2010).

Jarvik, E. Middle and Upper Devonian Porolepiformes form East Greenland with special reference to Glyptolepis groenlandica n. sp. Meddelelser om Grønland 187, 1-307 (1972).

Jarvik, E. in Problems in Vertebrate Evolution. (eds Andrews, S. M., Miles, R. S., Walker & A. D.) 199-225 (Linnean Symposium Series, London, 1977).

Jarvik, E. Basic Structure and Evolution of Vertebrates (Academic, 1980).

Karatajūte-Talimaa, V. in Fossil Fishes as Living Animals (ed. Mark-Kurik, E.) 223-232 (Academy of Sciences of Estonia, Tallinn, 1992).

Kesteven, H. L. The anatomy of the head of Callorhynchus antarcti-cus. Journal of Anatomy 67, 443-474 (1937).

Lane, J. A. Morphology of the braincase in the Cretaceous hybodont shark Tribodus linnae (Chondrichthyes: Elasmobranchii), based on CT scanning. Amer. Mus. Novitates 2758, 1-70 (2010).

Lane, J. A. & Maisey, J. G. Pectoral anatomy of Tribodus limae (Elasmobranchii: Hybodontiformes) from the Lower Cretaceous of Northeastern Brazil. Journal of Vertebrate Paleontology 29, 25-38 (2009).

Lane, J. A. & Maisey, J. G. The visceral skeleton and jaw suspension in the durophagous hybodontid shark Tribodus limae from the Lower Cretaceous of Brazil. Journal of Paleontology 86, 886-905 (2012).

Lehman, J. P. Les Arthrodires du Dévonien supérieur du Tafi lalt (Sud Marocain). Notes et Mémoires du Service Géologique du Maroc 129, 1-70 (1956).

Lehman, J. P. A propos de quelques Arthrodires et Ichthyodorulites sahariens. Mémoire IFAN 68, 193-200 (1964).

Lehman, J. P. Nouveaux poissons fossiles du Dévonien du Maroc. Annales de Paléontologie Vertébrés 62, 1-34 (1976).

Lehman, J. P. Sur la présence d’un Ostéolépiforme dans le Dévo-nien supérieur du Tafi lalt. Compte-Rendus de l’Académie des Sciences 285D, 151-153 (1977).

Lehman, J. P. A propos de deux poissons du Famennien du Tafi lalt. Annales de Paléontologie Vertébrés 64, 143-152 (1978).

Lelièvre, H., Janvier, P. L’Eusthénopteridé (Osteichthyes, Sarcopte-rygii) du Famennian (Dévonien supérieur) du Tafi lalt (Maroc): nouvelle description. Bulletin du Muséum National d’Histoire naturelle, 4e Série, Section C, Sciences de la Terre, Paléontolo-gie, Géologie, Minéralogie 3, 351-365 (1986).

Lelièvre, H., Janvier, P. Un Actinistien (Sarcopterygii, Vertebra-ta) dans le Dévonien supérieur du Maroc. Compte-Rendus de l’Académie des Sciences, Paris 307, 1425-1430 (1988).

Lelièvre, H., Janvier, P., Blieck, A. Silurian-Devonian vertebrate bio-stratigraphy of western Gondwana and related terranes (South America, Africa, Armorica-Bohemia, Middle East). Palaeozo-ic vertebrate biostratigraphy and biogeography, pp. 139-173 (1993).

132

Chapter III: Phoebodontid chondrichthyans of the Maider

Long, J. A. A new diplacanthoid acanthodian from the Late Devoni-an of Victoria. Memoirs of the Association of Australasian Pa-laeontologists 1, 51-65 (1983).

Long, J. A. Late Devonian chondrichthyans and other microverte-brate remains from northern Thailand. Journal of Vertebrate Paleontology 10, 59-71 (1990).

Long, J. A., Barwick, R. E., & Campbell. Osteology and function-al morphology of the osteolepiform fi sh Gogonasus andrewsae Long 1995, from the Upper Devonian Gogo Formation, Western Australia. Records of the Western Australian Museum Supple-ment 53, 1-89 (1997).

Long, J. A., Burrow, C. J., Ginter, M., Maisey, J., Trinajstic, K. M., Coates, M. I., Young, G. C. & Senden, T. J. First shark from the Late Devonian (Frasnian) Gogo Formation, Western Aus-tralia sheds new light on the development of tessellated calci-fi ed cartilage. PLoS ONE 10: e0126066 DOI:10.1371/journal.pone.0126066 (2015).

Lund, R. Harpagofututor volsellorhinus new genus and species (Chondrichthyes, Chondrenchelyiformes) from the Namurian Bear Gulch Limestone, Chondrenchelys problematica Traquair (Visean), and their sexual dimorphism. Journal of Paleontology 56, 938-958 (1982).

Lund, R.. Stethacanthid elasmobranch remains from the Bear Gulch Limestone (Namurian E2b) of Montana. American Museum No-vitates 2828, 1-24 (1985a).

Lund, R. The morphology of Falcatus falcatus (St. John and Worth-en), a Mississippian stethacanthid chndrichthyan from the Bear Gulch Limestone of Montana. Journal of Vertebrate Paleontol-ogy 5, 1-19 (1985b).

Lund, R. On Damocles serratus nov. gen. et sp., (Elasmobranchii: Cladodontida) from the Upper Mississippian Bear Gulch Lime-stone of Montana. Journal of Vertebrate Paleontology 6, 12-19 (1986).

Lund, R. & Grogan, E. D. Relationships of the Chimaeriformes and the basal radiation of the Chondrichthyes. Reviews in Fish Biol-ogy and Fisheries 7, 65-123 (1997).

Lund, R. & Grogan, E. D. in Recent Advances in the Origin and Ear-ly Radiation of Vertebrates (eds Arratia, G., Wilson, M. V. H. & Cloutier, R.) 171-187 (Friedrich Pfi el, 2004a).

Lund, R. & Grogan, E. D. in Recent Advances in the Origin and Ear-ly Radiation of Vertebrates (eds Arratia, G., Wilson, M. V. H. & Cloutier, R.) 505-531 (Friedrich Pfi el, 2004b).

Mader, H. Schuppen und Zähne von Acanthodiern und Elasmobran-chiern aus dem Unter-Devon Spaniens (Pisces). Göttinger Ar-beiten zur Geologie und Paläontologie 28, 1-59 (1986).

Maisey, J. G. The anatomy and interrelationships of Mesozoic hy-bodont sharks. Am. Mus. Novit. 2724, 1-48 (1982).

Maisey, J. G. Cranial anatomy of Hybodus basanus Egerton from the Lower Cretaceous of England. Am. Mus. Novit. 2758, 1-64 (1983).

Maisey, J. G. Cranial Morphology of the Fossil Elasmobranch Syn-echodus dubrisiensis. Am. Mus. Novit. 2804, 1-28 (1985).

Maisey, J. G. Visceral skeleton and musculature of a Late Devonian shark. J. Vertebr. Paleontol. 9, 174-190 (1989a).

Maisey, J. G. Hamiltonichthys mapesi g. & sp. nov. (Chondrichthy-es; Elasmobranchii), from the Upper Pennsylvanian of Kansas. American Museum Novitates 2931, 1-42 (1989b).

Maisey, J. G. in Major Events in Early Vertebrate Evolution (ed. Ahl-berg, P. E.) 263-288 (Taylor and Francis, 2001a).

Maisey, J. G. Remarks on the inner ear of elasmobranchs and its in-terpretation from skeletal labyrinth morphology. J. Morph. 250, 236-264. (2001b).

Maisey, J. G. Braincase of the Upper Devonian shark Cladodoides wildungensis (Chondrichthyes, Elasmobranchii), with observa-tions on the braincase in early chondrichthyans. Bull. Am. Mus. Nat. Hist. 288, 1-103 (2005).

Maisey, J. G. The braincase in Paleozoic symmoriiform and cladose-lachian sharks. Bull. Am. Mus. Nat. Hist. 307, 1-122 (2007).

Maisey, J. G. The postorbital palatoquadrate articulation in elasmo-branchs. Journal of Morphology 269, 1022-1040 (2008).

Maisey, J. G. The spine-brush complex in symmoriiform sharks (Chondrichthys; Symmoriiformes), with commenst on dorsal fn modularity. Journal of Vertebrate Paleontology 29, 14-24 (2009).

Maisey, J. G. The braincase of the Middle Triassic shark Acronemus tuberculatus (Bassani, 1886). Palaeontology 54, 417-428 (2011).

Maisey, J. G. The diversity of tessellated calcifi cation in modern and extinct chondrichthyans. Revue de Paléobiologie, Geneve 32, 355-371 (2013).

Maisey, J. G. & Anderson, M. E. A primitive chondrichthyan brain-case from the Early Devonian of South Africa. Journal of Verte-brate Paleontology 21, 702-713 (2001).

Maisey, J. G. & de Carvalho, M. R. A new look at old sharks. Nature 385, 779-780 (1997).

Maisey, J. G. & Lane, J. A. Labyrinth morphology and the evolution of low-frequency phonoreception in elasmobranchs. C. R. Pa-levol 9, 289-309. (2010)

Maisey, J. G., Miller, R. & Turner, S. The braincase of the chon-drichthyan Doliodus from the Lower Devonian Campbellton Formation of New Brunswick, Canada. Acta Zoologica 90 (sup-plement 1), 109-122 (2009).

Maisey, J. G., Miller, R., Pradel, A., Denton, J. S. S., Bronson, A. & Janvier, P. Pectoral morphology in Doliodus: bridging the ‘ac-anthodian’-chondrichthyan divide. American Museum Novitates 3875, 1-15. (2017).

Maisey, J. G., Turner, S., Naylor, G. J. P. & Miller, R. F. Dental pat-terning in the earliest sharks: implications for tooth evolution. Journal of Morphology. DOI:10.1002/jmor.20242 (2013)

Marinelli, W. & Strenger, A. Vergleichende Anatomie und Morpholo-gie der Wirbeltiere. III. 174-308 (Franz Deuticke, Wien, 1959).

Miles, R. S. Articulated acanthodian fi shes from the Old Red Sand-stone of England, with a review of the structure and evolution of the acanthodian shoulder- girdle. Bull. Br. Mus. Nat. Hist. (Geol.) 24, 111-213 (1973a).

Miles, R. S. in Interrelationships of Fishes (eds Greenwood, P. H., Miles, R. S. & Patterson, C.) 63-103 (Academic, 1973b).

Miller, R. F., Cloutier, R. & Turner, S. The oldest articulated chon-drichthyan from the Early Devonian period. Nature 425, 501-504 (2003).

Moy-Thomas, J. A. The structure and affi nities of Chondrenchelys problematica Tr. Proceedings of the Zoological Society, Lon-don1935, 391-403 (1935).

Mutter, R. J., de Blanger, K., & Neuman, A. G. Elasmobranchs from the Lower Triassic Sulphur Mountain Formation near Wapiti Lake (BC, Canada). Zoological Journal of the Linnean Society 149, 309-37 (2007).

Mutter, R. J., Neuman, A. G. & de Blanger, K. Homalodontus nom. nov. a replacement for Wapitiodus Mutter, de Blanger and Neu-man 2007 (Homalodontidae nom. nov., ?Hybodontoidea), pre-occupied by Wapitiodus Orchard, 2005. Zoological Journal of the Linnean Society 154, 419-420 (2008).

Nelson, G. J. in Current problems of lower vertebrate phylogeny. (ed. T. Ørvig) 129-143 (Almqvist & Wiksell, Stockholm, 1968).

Nelson, G. J. Gill arches and the phylogeny of fi shes, with notes on the classifi cation of vertebrates. Bull. Am. Mus. Nat. Hist. 141, 475-552 (1969).

Nelson, G. J. Pharyngeal denticles (placoid scales) of sharks with notes on the dermal skeleton of vertebrates. Amer. Mus. Novi-tates 2416, 1-26 (1970).

Newberry, J. S. The Paleozoic fi shes of North America, Monograph of the U.S. Geological Survey 16, 1–340 (1889).

Newman, M. J., Davidson, R. G., den Blaauwen, J. L. & Burrow, C. J. The Early Devonian acanthodian Uraniacanthus curtus (Powrie, 1870) n. comb., from the Midland Valley of Scotland. Geodiversitas 34, 739-759 (2012).

Oelofsen, B. W. A fossil shark neurocranium from the Permo-Car-boniferous (lowermost Ecca Formation) of South Africa. In In-do-Pacifi c fi sh biology. Proceedings of the Second International Conference on Indo-Pacifi c Fishes. Ichthyological Society of Japan, Tokyo, pp. 107-124 (1986).

Patterson, C. The phylogeny of the chimaeroids. Philosophical Transactions of the Royal Society of London, Series B 249, 101-219 (1965).

Patterson, C. Morphology and interrelationships of primitive acti-nopterygian fi shes. American Zoologist 22, 241-259 (1982).

Patterson, C. Interpretation of the toothplates of chimaeroid fi shes. Zool. J. Linn. Soc. 106, 33-61 (1992).

Pearson, D. M. & Westoll, T. S. The Devonian actinopterygian Chei-rolepis Agassiz. Trans. R. Soc. Edinb. 70, 337-399 (1979).

Pradel, A. Skull and brain anatomy of Late Carboniferous Siby-rhynchidae (Chondrichthyes, Iniopterygia) from Kansas and Oklahoma (USA). Geodiversitas 32, 595-661 (2010).

Pradel A., Didier, D., Casane, D., Tafforeau, P. & Maisey J. G. Ho-

133

Chapter III: Phoebodontid chondrichthyans of the Maider

locephalan embryo provides new information on the evolution of the glossopharyngeal nerve, metotic fi ssure and parachordal plate in gnathostomes. PLoS ONE 8: e66988 DOI:10.1371/jour-nal.pone.0066988 (2013).

Pradel A., Langer M., Maisey J. G., Geffard-Kuriyama D., Cloetens P., Janvier P., & Tafforeau P. Skull and brain of a 300 million-year-old chimaeroid fi sh revealed by synchrotron holotomog-raphy. Proceedings of the National Academy of Sciences 106, 5224-5228 (2009).

Pradel, A., Maisey, J. G., Tafforeau, P., Mapes, R. H. & Mallatt, J. A Palaeozoic shark with osteichthyan-like branchial arches. Na-ture 509, 608-611 (2014).

Pradel, A., Tafforeau, P. & Janvier P. Study of the pectoral girdle and fi ns of the Late Carboniferous sibyrhynchid iniopterygians (Ver-tebrata, Chondrichthyes, Iniopterygia) from Kansas and Okla-homa (USA) by means of microtomography, with comments on iniopterygian relationships. Comptes Rendus Palevol 9, 377-387 (2010).

Pradel A., Tafforeau P., Maisey J. G. & Janvier P. A new Paleo-zoic Symmoriiformes (Chondrichthyes) from the Late Car-boniferous of Kansas (USA) and Cladistic Analysis of Early Chondrichthyans. PLoS ONE 6: e24938 DOI:10.1371/journal.pone.0024938 (2011).

Qu, Q., M., Zhu, M. & Wang, W. Scales and dermal skeletal histolo-gy of an early bony fi sh Psarolepis romeri and their bearing on the evolution of rhombic scales and hard tissues. PLoS One 8,

e61485 (2013a).Qu, Q., Sanchez, S., Blom, H., Tafforeau, P. & Ahlberg P. E. Scales

and tooth whorls of ancient fi shes challenge distinction between external and oral ‘teeth’. PLoS ONE 8, DOI:10.1371/journal.pone.0071890 (2013b).

Qiao, T., King B., Long J. A., Ahlberg P. E., & Zhu M. Early gnatho-stome phylogeny revisited: multiple method consensus. PLoS ONE 11, DOI:10.1371/journal.pone.0163157 (2016).

Reif, W. E. Types of morphogenesis of the dermal skeleton in fossil sharks. Paläont. Z. 52, 110-128 (1978).

Reif, W. E. Squamation and ecology of sharks. Cour. Forsch.-Inst. Senckenberg 78, 1-255 (1985).

Rieppel, O. A new genus of shark from the Middle Triassic of Monte San Giorgio, Switzerland. Palaeontology 25, 399-412 (1982).

Rücklin M. A new Frasnian placoderm assemblage from the eastern Anti-Atlas, Morocco, and its palaeobiogeographical implica-tions. Palaeoworld 19, 87-93 (2010).

Rücklin M. First selenosteid placoderms from the eastern Anti-Atlas of Morocco; osteology, phylogeny and palaeogeographical im-plications. Palaeontology 54, 25-62 (2011).

Rücklin, M., Clément, G. Une revue des Placodermes et Sarcoptéry-giens du Dévonien du Maroc, in: Zouhri, S. (ed), Paléontologie des vertébrés du Maroc: état des connaissance, Mémoires de la Société Géologique de France 180, p. 624 (2017).

Rücklin, M., Long, J. A., Trinajstic, K. A new selenosteid arthrodire (‘Placodermi’) from the Late Devonian of Morocco. Journal of Vertebrate Paleontology 35(2), e908896, 1-13 (2015).

Schaeffer, B. The xenacanth shark neurocranium, with comments on elasmobranch monophyly. Bull. Am. Mus. Nat. Hist. 169, 1-66 (1981).

Schultze, H.NP. & Zidek, J. Ein primitiver acanthodier (Pisces) aus dem Unterdevon Lettlands. Paläontologische Zeitschrift 56, 95-105 (1982).

Seidel, R., Lyons, K., Blumer, M., Zalansky, P., Fratzl, P., Weaver, J. C. & Dean, M. N. Ultrastructural and developmental features of the tessellated endoskeleton of elasmobranchs (sharks and rays). J. Anat. DOI:10.1111/joa.12508 (2016).

Smith, B. G. The Anatomy of the Frilled Shark, Chlamydoselachus anguineus Garman. Bashford Dean Memorial Volume: Archaic Fishes Article 6, 333-506. American Museum of Natural Histo-ry, N.Y (1937).

Solér-Gijon, R. & Hampe, O. Evidence of Triodus Jordan 1849 (Elasmobranchii: Xenacanthidae) in the Lower Permian of the Autun basin (Muse, France). N. Jb. Geol. Paläont. Mh. 1998, 335-348 (1998).

Stahl, B. J. Reconstruction of the head skeleton of the fossil elas-mobranch, Phoebodus heslerorum (Pisces, Chondrichthyes). Copeia 4, 858-866 (1988).

Stahl, B. J. in Handbook of Paleoichthyology Vol. 4 (ed. Schultze, H.-P.) (Friedrich Pfeil, München. 1999).

St. John, O. and Worthen, A. H.. Description of fossil fi shes. Geolog-ical Survey of Illinois 6(2), 245-488 (1875A).

Thomson, K. S. The endocranium and associated structures in the Middle Devonian rhipidistian fi sh Osteolepis. Proceedings of the Linnean Society of London 176, 181-195 (1965).

Tucker A. S. & Fraser, G. J. Evolution and developmental diversity of tooth regeneration. Semin Cell Dev Biol DOI:10.1016/j.sem-cdb.2013.12.013 (2014).

Turner, S. Middle Palaeozoic elasmobranch remains from Australia. Journal of Vertebrate Paleontology 2, 117-131 (1982).

Turner, S., Burrow, C. J. & Warren, A. Gyracanthides hawkinsi sp. nov. (Acanthodii, Gyracanthidae) from the Lower Carbonifer-ous of Queensland, Australia, with a review of gyracanthid taxa. Palaeontology 48, 963-1006 (2005).

Valiukevicius, J. in Fossil Fishes as Living Animals (ed. Mark-Kurik, E.) 193-213 (Academy of Sciences of Estonia, Tallinn, 1992).

Warren, A., Currie, B. P., Burrow, C. & Turner, S. A redescription and reinterpretation of Gyracanthides murrayi Woodward 1906 (Acanthodii, Gyracanthidae) from the Lower Carboniferous of the Mansfi eld Basin, Victoria, Australia. Journal of Vertebrate Paleontology 20, 225-242 (2000).

Watson, D. M. S. The acanthodian fi shes. Philosophical Transac-tions of the Royal Society of London B 228, 49-146 (1937).

Wells, J. W. Fish remains from the Middle Devonian bone beds of the Cincinnati Arch region. Palaeontographica Americana 3, 5-62 (1944C).

Williams, M. E. The ‘‘cladodont level’’ sharks of the Pennsylvanian Black Shales of central North America. Palaeontographica 190, 83-158 (1985).

Williams, M. E. A new specimen of Tamiobatis vetustus (Chondrich-thyes, Ctenacanthoidea) from the Late Devonian Cleveland Shale of Ohio. Journal of Vertebrate Paleontology 18(2), 251-260 (1998).

Williams, M. E. Tooth retention in cladodont sharks: with a compar-ison between primitive grasping and swallowing, and modern cutting and gouging feeding mechanisms. Journal of Vertebrate Paleontology 21, 214-226 (2001).

Woodward, A. S. & White, E. I. The dermal tubercles of the Upper Devonian shark, Cladoselache. Annals and Magazine of Natural History 11, 367-368 (1938).

Yu, X. A new porolepiform-like fi sh, Psarolepis romeri, gen. et sp. nov. (Sarcopterygii, Osteichthyes) from the Lower Devonian of Yunnan, China. J. Vertebr. Paleontol. 18, 261-264 (1998).

Zangerl, R. Chondrichthyes I: Paleozoic Elasmobranchii. In: Schul-tze, H. P. (ed.), Handbook of Paleoichthyology 3A, 115 pp. Gus-tave Fischer, Stuttgart, New York (1981).

Zangerl, R. & Case, G. R. Iniopterygia, a new order of chondrich-thyan fi shes from the Pennsylvanian of North America. Fieldi-ana: Geology 6, 1-67 (1973).

Zangerl, R. and Case, G. R. Cobelodus aculeatus (Cope), an anacan-thous shark from Pennsylvanian Black Shales of North America. Palaeontographica A 154, 107-57 (1976).

Zhu, M. & Schultze, H. P. The oldest sarcopterygian fi sh. Lethaia 30, 293-304 (1997).

Zhu, M. & Schultze, H. P. in Major Events in Early Vertebrate Evo-lution (Palaeontology, phylogeny, genetics, and development). (ed. Ahlberg, P. E.) 289-314 (Taylor and Francis, 2001).

Zhu, M & Yu, X. A primitive fi sh close to the common ancestor of tetrapods and lungfi sh. Nature 418, 767-770 (2002).

Zhu, M., Yu, X, & Ahlberg, P. E. A primitive sarcopterygian fi sh with an eyestalk. Nature 410, 81-84 (2001).

Zhu, M., Yu, X., Ahlberg, P. E., Choo, B., Lu, J., Qiao, Q., Zhao, L. J., Blom, H., & Zhu, Y. A Silurian placoderm with osteich-thyan-like marginal jaw bones. Nature 52, 188-193 (2013).

Zhu, M., Yu, X. & Janvier, P. A primitive fossil fi sh sheds light on the origin of bony fi shes. Nature 397, 607-610 (1999).

Zhu, M., Zhao, W., Jia, L., Lu, J., Qiao, T. & Qu, Q. The oldest artic-ulated osteichthyan reveals a mosaic of gnathostome characters. Nature 458, 469-474 (2009).

Zidek, J. Late Pennsylvanian Chondrichthyes, Acanthodii, and deep-bodied Actinopterygii from the Kinney Quarry, Manzani-ta Moutains, New Mexico. In Geology and paleontology of the Kinney Brick Quarry, Late Pennsylvanian, central New Mexi-co. J. Zidek ed. Bulletin 138, New Mexico Bureau of Mines & Mineral Resources (Socorro: New Mexico Bureau of Mines & Mineral Resources), pp. 199-214. (1992).

CHAPTER IV

Functional morphology of mandibular arches in symmoriids

as exemplifi ed by Ferromirum oukherbouchi gen. et sp. nov.

(Late Devonian)

Linda Frey, Michael Coates, Martin Rücklin and Christian Klug

In preparation, formatted for Science Advances

137

Chapter IV: Functional Morphology of Symmoriid Jaws

Functional morphology of mandibular arches in symmoriids as ex-

emplifi ed by Ferromirum oukherbouchi gen. et sp. nov. (Late Devoni-

an, Morocco)

L. Frey1*, M. I. Coates2, M. Rücklin3 and C. Klug1

1Paläontologisches Institut und Museum, University of Zurich, Karl-Schmid-Strasse 4, CH-8006 Zürich (linda.frey@pim.uzh.ch; chklug@pim.uzh.ch). 2Department of Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th St., USA-60637 Chicago.3 Naturalis Biodiversity Center, Postbus 9517, 2300 RA, Leiden, The Netherlands.

The functional morphology of mandibular and branchial arches in early chondrichthyans is poorly known because of the lack of articulated and undistorted fossil material. A recently discovered exceptionally well-preserved specimen of the symmoriiform Ferromirum oukherbouchi gen. et sp. nov. of Famennian age from the southern Maïder (Morocco) yields new information about the anatomy and function of the cranial and visceral skeleton. A three-dimensional model based on CT-scans of the holotype shows the undeformed mandibular and branchial arches such as the hyoids and ceratohyals allowing the reconstruc-tion of mandible movement during feeding. The way the Meckel’s cartilages rotate around their sagittal axes was previously unknown from chondrichthyans and probably became extinct with the end of the symmoriid clade. At the same time, the new species corroborates that cranial morphology of Palaeozoic symmoriiforms is quite conservative and allowed to falsify the aphetohyoidean hypothesis for these early chondrichthyans, because in the new taxon, the hyoid is tightly attached to the lower jaw.

Key words: chondrichthyans, gnathostomes, jaws, Famennian, Maïder, Palaeozoic

1. Introduction

The evolution of the structured visceral skeleton including jaws was a fundamental step in ver-tebrate evolution as it opened up the access to a much greater variety of food sources. The visceral skeleton of chondrichthyans, osteichthyans, and extinct stem gnathostomes including placoderms and acanthodians consists of paired, serially ar-ranged lower and upper jaws, jaw supporting el-ements (hyoids and ceratohyals) and gill arches [1-6]. Knowledge of morphological details and the function of jaws in Devonian chondrichthyans is still poor, mostly due to incompleteness or de-formation of specimens. With a few exceptions [7-9], the visceral skeleton and the jaws are of-ten disarticulated and/ or distorted by compaction or tectonics. Therefore, reconstructions of feed-ing mechanisms of Palaeozoic chondrichthyans are largely based on tooth morphology and ar-rangement in combination with comparisons to analogous or homologous conditions in Recent chondrichthyans [10-15]. As in modern chon-drichthyans, the dentitions of Devonian chon-drichthyans display a great morphologic disparity corresponding to a similarly wide range of feed-ing strategies. Chondrichthyans with cladodont or phoebodont teeth were grasping prey, which they

swallowed in one piece while forms with prot-acrodont or orodont teeth were likely duropha-gous [14]. Filter feeding chondrichthyans such as Diademodus were rarely reported from the Palae-ozoic so far; they usually have minute teeth com-pared to jaw size [13]. Other feeding modes such as suction feeding were inferred for hybodontid chondrichthyans from the Carboniferous based on their mandibular and branchial skeletons [16].

The function of jaws and branchial arches of the Symmoriiformes is hardly known although it is a very common and geographically widely distributed group of early chondrichthyans with cladodont teeth. It is known from the Devonian and Carboniferous and was recently assigned to the holocephalans branch within the chondrich-thyans [17]. Although complete skeletons [18-23] and braincases [17, 24-26] of several species were described in the last decades, branchial arches and jaws in three-dimensional preservation remained unknown. In a recently discovered symmoriiform chondrichthyan from the Devonian of Morocco, superbly preserved and articulated branchial and mandibular arches are preserved. These remains reveal the fi rst insights into the feeding mecha-nism of these early holocephalans.

138

Chapter IV: Functional Morphology of Symmoriid Jaws

2. Results

2.1 Systematic palaeontology and anatomical

description

Class Chondrichthyes Huxley, 1880Order Symmoriiformes Zangerl, 1981Family ?Falcatidae Zangerl, 1990Genus Ferromirum gen. nov.

Type species. Ferromirum oukherbouchi gen. et sp. nov.

Etymology. Derived from ferrum (lat. - iron) and mirus (lat. - miraculous). Ferrum is includ-ed because of the preservation of the holotype of the type species in a reddish ferruginous nodule, which is characteristic for fossils from the Thyla-cocephalan Layer of the Maïder. Mirus refers to the fact that we erroneously interpreted the gill re-mains of the holotype as appendages of a crusta-cean, and it was like a miracle when a chondrich-thyan emerged.

Genus defi nition. Small symmoriid with slen-der body; head with rounded triangular outline, rostrum protruding anterior of the mouth; large orbits; tessellated cartilage; jaws amphystylic; cladodont teeth; cleaver-shaped palatoquadrate; fi ve gill arches; otico-occipital fi ssure; narrow suborbital shelf; palatoquadrate ventrally sig-moid; coronoid process on Meckel`s cartilage; tri-angular pelvic girdle; anterior fi n spine broad and dorsally recurved.

Included species. Only the type species.

Systematic remarks. Although the cladistics analysis did not resolve the family-position of the new taxon, we tentatively assign it to the Fal-catidae for the following reason: There are cur-rently seven other genera included in this clade: Dwykaselachus has a short rostrum; Ozarcus has a different geometry of the palatoquadrate and a rostrum like in Ferromirum seems missing; Cladoselache has short fi n spines; Cobelodus lacks the anterior dorsal fi n and fi n spine as well as a shorter rostrum; the jaws are quite similar in Ferromirum and Akmonistion, but the latter has a large spine-brush complex; Damocles and Fal-catus share the small body size, the slender body, similar jaws, a neurocranium protruding anterior-ly in front of the palatoquadrate, and the strongly developed dorsal fi n spine above the pectoral gir-dle with Ferromirum but differ in the shape of the fi n spine. Taking these differences and similarities

into account, we suggest that Ferromirum might be the only Devonian and thus oldest member of the Falcatidae.

Ferromirum oukherbouchi gen. et sp. nov.

Holotype. PIMUZ A/I XXXX

Material. Only the holotype.

Locality and horizon. Famennian, Planitornoc-eras euryomphalum to Afrolobites mrakibensis Zone; Ibaouane Formation, Lahfi ra Member, Thy-lacocephalan Layer (formerly described as Phyl-locarid Layer; [27]), Madene el Mrakib, Maïder Basin, southeastern Anti-Atlas, Morocco.

Etymology. The species name oukherbouchi hon-ours the fi nder of the specimen Said Oukherbouch (Tafraoute).

Species defi nition. As for genus.

Description

The complete body of Ferromirum oukherbouchi gen. et sp. nov. is approximately 33 cm long. It was prepared from its ventral side. Thus, ventral parts of the pectoral and pelvic girdles, branchi-al and mandibular arches and of the left orbit are exposed (Fig. 1A, B). In the anterior part of the head region, a rostrum like in Falcatus and Dam-ocles [20-21] is present and some soft tissues such as both elongate wings of the liver, parts of the digestive tract and parts of the body outline are preserved. The computed tomograms and the re-constructed 3D-model show much more anatom-ical details of the braincase, pectoral and pelvic girdles, as well as a fi n spine (Fig. 2A-D). The visceral skeleton shows a basic arrangement with serially arranged paired mandibular and hyoid arches and fi ve gill arches as known from Ozarcus mapesae [8].

Mandibular arches

The mandibular arches underwent very little dis-tortion and compression (Fig. 3A-I) and there-fore, they represent the best-preserved jaws cur-rently known from symmoriid chondrichthyans. The palatoquadrate of Ferromirum gen. nov. is cleaver-shaped with a high otic process, which is a common feature in symmoriids and other Pa-laeozoic chondrichthyans [10, 28]. Anteriorly, the otic process articulates with the postorbital pro-

139

Chapter IV: Functional Morphology of Symmoriid Jaws

Fig. 1. Ferromirum oukherbouchi gen. et sp. nov., PIMUZ XXXX, early/ middle Famennian, Madene el Mrakib. (A) Photo and (B) line drawing of the specimen. (C) Head region including parts of the braincase, sclerotic ring, mandib-ular arches and branchial skeleton and shoulder girdles from ventral view. (D) Soft tissue remains including liver and spiral valves. (E) Pelvic and caudal region. Abbreviations - chy: ceratohyal; cop: copula; cbr: ceratobranchials; fs: fi n spine; liv: liver; mc: Meckel`s cartilage; p.pl: pelvic plate; pq: palatoquadrate; ros: rostrum; scl.r: sclerotic ring; scor; scapulacoracoid; stc?: stomach content; spv: spiral valves. Scales: A-B = 100 mm; C-E = 30 mm.

140

Chapter IV: Functional Morphology of Symmoriid Jaws

Fig. 2. Ferromirum oukherbouchi gen. et sp. nov. PIMUZ XX, virtually reconstructed specimen based on CT-data showing the neurocranium, mandibular arches the pectoral girdle and the dorsal fi n spine. Ventral (A) and dorsal view with (B) and without (C) braincase. (D) lateral view. Colour coding: grey, braincase; turquoise, palatoquadrate; yellow, Meckel’s cartilage; dark green, hypohyal; light blue, hyoid; orange, ceratohyal; blue, epihyals; red, cerato-branchials; green, copula; brown, fi n spine; purple, shoulder girdle; light turquoise, ? neural arches.

cess of the neurocranium. A distinctive otic crest at the dorsoposterior margin of the palatoquadrate is present. A second smaller crest is situated on the most anterior part of the dorsal margin of the otic process (anterodorsal crest) that serves as a support for nerve VII (Fig. 3C, D). Laterally, the quadrate region of the palatoquadrate is strongly

concave forming a large attachment area for ad-ductor muscles. The ventral margin of the entire palatoquadrate is sigmoid like in Stethacanthidae [19, 23] and Falcatidae [20-21]. Dorsally, the pal-atine region is mediolaterally expanded similar to Ozarcus [8]. Anteromedially, a serrated margin articulates with the ethmoid region of the neuro-

141

Chapter IV: Functional Morphology of Symmoriid Jaws

Fig. 3. Mandibular arches of Ferromirum oukherbouchi gen. et sp. nov., PIMUZ XX. Right and left palatoquadrates in dorsal (A) and ventral (B) view. Right palatoquadrate, lateral (C) and medial (D) view. (E) Right and left Meck-el’s cartilage in ventral aspect. Right Meckel’s cartilages in lateral (F), medial (G), dorsal (H) and ventral (I) views. Abbreviations: adc, anterodorsal crest; gl, glenoid; ma, mandibular articulation; mp, mandibular process; oa: orbital articulation; oaf, otic articular fossa; opr, otic process; ppr, palatine process; sym, symphysis.

cranium. Like the palatoquadrate, the Meckel`s cartilages have a prominent lateral concavity in the posterior portion (Fig. 3E-I). The ventroposte-rior jaw margin forms a distinctive crest. Dorsal-ly, the mediolateral expanded margin bears eight small circular concavities for tooth families. At two thirds of its length, the dorsal margin of the Meckel`s cartilage shows a coronoid process pos-teriorly followed by a concavity similar to Falca-tus [20]. For the articulation with the palatoquad-rate, two processes including the mesial process (also known as mandibular knob; [29]) and the

glenoid mandibular process are present posterior-ly of the Meckel`s cartilage.

Branchial arches

Like in Ozarcus, the preserved hyoid arches in-clude paired epihyals, ceratohyals and hypohyals [8], while pharyngohyals, interhyals and basihy-als are not preserved (maybe poorly calcifi ed) in Ferromirum gen. nov. Both the ceratohyals and epihyals are closely aligned to the mandibular arches throughout their complete length. This

142

Chapter IV: Functional Morphology of Symmoriid Jaws

contrasts the condition in Ozarcus and Cobelodus where some space seems to be left between the hyoid and mandibular arches (fi n 3 a in [8]; [30]). With the new anatomical data of Ferromirum gen. nov. provided here, the supposed space between the hyoid and mandibular arches in Ozarcus and Cobelodus is likely taphonomically biased. Both the upper and lower hyoid arches are slightly curved and posteriorly, the hyoid is inserted in the articular notch of the ceratohyal. Anteriorly, the dorsoventrally broad end of the hyoid articulates with the lateral otic region of the braincase.

From the gill arches, fi ve pairs of epibranchi-als and of seven ceratobranchials are present. All are rod-shaped, and have a smooth surface (unlike Tristychius [31]). The basibranchial copula [32] in Ferromirum gen. nov. is long and of rectangu-lar shape but its articulation with basibranchials is unknown. Smaller elements such as hypobran-chials, infrapharyngobranchials and suprapharyn-gobranchials reported from Ozarcus [8] are not recognizable.

Neurocranium and sclerotic ring

The neurocranium of Ferromirum gen. nov.is somewhat deformed. It shows a somewhat com-pressed ethmoidal and orbital region, while the otic and occipital regions are three-dimensionally preserved (Fig. 4A-D). The overall shape of the braincase shows the affi nity of this specimen to other symmoriids. At the anterolateral edges of the narrow subotic shelf of the ethmoid, a serrated margin for the articulation with the palatine ramus of the palatoquadrate is present. The orbital region shows the common condition as in holocephalans: its size is very large and about the same length as the otic and occipital regions together [17]. A large opening for the optic nerve II is perforating the interorbital wall. The postorbital process is laterally broken but it is rather thin anteroposte-riorly compared to the rest of the braincase. From the dorsal view, only little anatomical detail of the otic region is recognizable. Characteristical-ly for early chondrichthyans, the occipital unit is wedged between the otic capsule and traces of an otic-occipital fi ssure are preserved. The hyoman-dibula articulates with the otic unit posterior to the postorbital process. However, a periotic pro-cess is not recognizable where the hyomandibula is supposed to articulate (see e.g., Cobelodus in [25]; Dwykaselachus in [17]). Ventrally and pos-teriorly to the postorbital process, the otic region shows a waist typical for symmoriids [e.g., 17]. The otic region and the glossopharyngeal canals are fl oored by a hypotic lamina, which exhibits

two openings for the lateral dorsal aortae far pos-teriorly. In the occipital region, the occipital plate is perforated by the foramen magnum.

Remains of a deformed sclerotic ring are ex-posed (Fig. 1A-C), but its fi ne morphological de-tails are not preserved. Sclerotic rings are formed by numerous sclerotics in Cladoselache [33], Fal-catus [20] and Damocles [21].

Pectoral girdle

Right and left parts of the pectoral girdle are pres-ent, where the left part is better preserved. The scapulacoracoid of Ferromirum gen. nov. has a shape characteristic for symmoriiform chondrich-thyans [e.g. 10, 24]. The fl at, sheet-like scapula is dorsoventrally long and bears an anteriorly directing process (anterior process) at the dorsal apex (Fig. 5A-E). The region bearing the posteri-ordorsal process is broken (compare fi g. 10A-C in [24]). Anteriorly and posteriorly, the scapula has a concave outline. Towards the ventral end, the scapulacoracoid is mediolaterally broadening. In ventral view, the base of the scapulacoracoid ap-pears triangularly and its posterior portion shows a concavity for the articulation with the proximal radials of the pectoral fi n. The coracoid region is convex anteriorly and concave posteriorly. A pro-coracoid has not been detected but was probably present as in, e.g., Akmonistion and other symmo-riids.

Pelvic girdle

The pelvic girdle is poorly preserved in Fer-romirum gen. nov.; only a small, simple triangular plate is visible posterior of a pyrite concretion, which possibly is located in the middle of the body (Fig. 1B, E). In other symmoriiform chondrich-thyans such as Akmonistion, Cobelodus, Denaea and Symmorium, the pelvic plate is subtrianglar to oval in shape [10, 24]. In Falcatus, it is triangular but the anterolateral edge is concave [20]. Trian-gular plates are present in Cladoselache (fi g. 18 in [33]) and xenacanthids [fi g. 12a-b in [34]; fi g. 14 in [35]).

Fin spine

A dorsal fi n spine on the pectoral level is pre-served between the pectoral girdle and the pos-terior end of the neurocranium in Ferromirum gen. nov.. It resembles the fi ns spines of cladose-lachians [10, 36] in having an anteroposteriorly broad shape and a strongly recurved dorsal apex. Its position is comparable to genera such as Fal-catus or Stethacanthus. By contrast, the fi n spine

143

Chapter IV: Functional Morphology of Symmoriid Jaws

Fig. 4. Ferromirum oukherbouchi gen. et sp. nov., PIMUZ XX. Neurocranium in dorsal (A), ventral (B), lateral (C) and posterior (D) views. (E) Articulation between braincase and visceral arches. (F-G) Arrangement of mandibular and branchial arches. Colour coding: grey, braincase; turquoise, palatoquadrate; yellow, Meckel’s cartilage; dark green, hypohyal; light blue, hyoid; orange, ceratohyal. Abbreviations: fm, foramen magnum; hl, hypotic lamina; hya, hyomandibular articulation; glc, glossopharyngeal canal; oa, orbital articulation; ocpl, occipital plate; oof, otico-oc-cipital fi ssure; popr, postorbital process; sup.s, supraorbital shelf; II, optic nerve.

Fig. 5. Virtually reconstructed pectoral elements and the fi n spine (possibly slightly distorted) of Ferromirum oukher-bouchi gen. et sp. nov., PIMUZ XX. Left part of the pectoral girdle in anterior (A), lateral (B, D), posterior (C) and ventral (E) views. (F) dorsal fi n spine of the pectoral fi n-level. Abbreviations: apr, anterior process; cor, coracoid; ppr, posterior process; sc, scapula.

144

Chapter IV: Functional Morphology of Symmoriid Jaws

of Ferromirum gen. nov. is longer and more slen-der than in Cladoselache (Fig. 5F). The dorsal fi n on the pelvic level is not visible in the CT-scan and possibly absent.

2.2 Phylogenetic relationships

Phylogenetic analyses resulted in 730 parsimoni-ous trees of 545 steps. The strict consensus tree based on the data matrix including 228 characters, 66 ingroup taxa and one outgroup taxon plac-es Ferromirum gen. nov. within the Symmorii-formes (Fig. 6, S1). Ferromirum gen. nov. shares the narrow interorbital space, the absence of anal fi ns, the presence of a fi n spine at pectoral level and a longer orbit compared to the otic unit (in Ferromirum gen. nov. only subtly longer) with other stem Holocephali. The presence of a scle-rotic ring is shared with other Symmoriiformes (Cladoselache, Falcatus and Damocles).

Although our phylogenetic analyses does not ful-ly resolve the relation within the symmoriiform clade, the small size, body proportions, shape of the head (including shape of the palatoquadrate, pointed rostrum) and the presence of one fi n spine in the pectoral region of Ferromirum gen. nov. are reminiscent of the Falcatidae (Fig. 7). In the light of this systematic proximity, the absence of a well-developed dorsal fi n and a posterior fi n spine can be considered primary. An assignment to this family would extend the stratigraphic range of the Falcatidae from the Early Carboniferous into the Late Devonian, which is not surprising tak-ing the bizarre morphological specialisations of the Carboniferous falcatids into account. More discoveries of postcranial material of Dwykasela-chus, Ozarcus and Ferromirum, in particular, will help reconstructing the phylogenetic relationships among symmoriids and testing the hypothesis of Ferromirum being a falcatid.

Doliodus

Acronemus

Egertonodus

Hamiltonichthys

Onychoselache

Tribodus

Squalus

Synechodus

Tristychius

Homalodontus

Cladodoides

Phoebodus

Thrinacodus

Diplodoselache

Orthacanthus

Triodus

Tamiobatis

Dwykaselachus

Ozarcus

Cladoselache

Cobelodus

Akmonistion

Damocles

Falcatus

Debeerius

Chimaeroidei

Chondrenchelys

Helodus

Iniopera

Kawichthys

Ferromirum gen. nov

Fig. 6. Crown part of the strict consensus tree showing phylogenetic affi liation of Ferromirum gen. nov. to sym-moriform chondrichthyans. Colour coding: orange, stem Chondrichthyes without Acanthodii; blue, Elasmobranchii (crown Chondrichthyes); purple, Holocephali (crown Chondrichthyes). White circles: bootstrap support of knot > 50% and/ or Bremer decay values > 1; black circles: bootstrap support > 75% and/or Bremer decay values > 3. For the complete cladogram, see Fig. S1.

145

Chapter IV: Functional Morphology of Symmoriid Jaws

Fig. 7. Possible reconstruction of Ferromirum oukherbouchi gen. et sp. nov. and the thylacocephalans found in the

Famennian of the Maïder region of Morocco.

2.3 Functional morphology of the mandibular

arches

Symmoriiformes show morphological conserva-tism in the jaw to braincase articulation among all its genera. This was tested by rescaling the braincase of Dwykaselachus oosthuizeni recon-structed by Coates [17] to the dimensions of the well-preserved jaws of Ferromirum oukherbouchi gen. et sp. nov. and by virtually combining them. All these elements fi t perfectly together, corrob-orating their close relationships and functional similarities. The quadrate process articulates an-teriorly with the postorbital process and serrated edges of the palatine ramus joints with the orbital articulation of the braincase (Fig. 8A-B).

Using a 3D-print of the computationally vi-sualized 3D-model, the movement of the jaws was reconstructed. The shape of the jaw articula-tion makes the Meckel`s cartilage rotate laterally while it is dropping. Therefore, a larger surface of the dentition is presented to the water column and prey (Fig. XX and video in preparation). When

the animal closed its mouth, the Meckel’s carti-lage rotates back into its initial position, i.e. both lower jaws rotated inward, possibly thereby im-proving the grip on prey items.

3. Discussion

The neurocranial-mandibular articulation is quite conservative in symmoriiform chondrichthyans as demonstrated by the perfect fi t between the palatoquadrate of the Late Devonian Ferromirum oukherbouchi gen. et sp. nov. and the braincase of the much younger Early Permian Dwykaselachus. The jaws fi t similarly well to the braincase of oth-er symmoriiforms such as Akmonistion or Cobe-lodus. Therefore, this type of articulation and its function changed hardly through the evolution of this group.

The three-dimensionally preserved mandibu-lar arches enabled us to reconstruct the jaw func-tion of these early chondrichthyans. Although the

146

Chapter IV: Functional Morphology of Symmoriid Jaws

Fig. 8. Neurocranium of Dwykaselachus oosthuizeni Oelofsen, 1986 virtually articulated with the mandibular arches (pink and blue) of Ferromirum oukherbouchi gen. et sp. nov. A, mouth closed. B, mouth opened; note the inward rotation along the sagittal axes when the mouth closes and the outward rotation during opening, which created a larger surface exposing functional teeth.

feeding mechanisms in extant chondrichthyans are also poorly known, they display a high diversity in prey capture including ram feeding, biting, suc-tion feeding, and fi lter feeding [37]. By contrast, the jaws are amphystylic in Palaeozoic chondrich-thyans, thus implying a rather stiff articulation be-tween the braincase and the jaws. Therefore, they did not perform jaw propulsion while snatching the prey as observable in extant elasmobranchs with hyostylic jaws. The amphystylic jaw articu-lation combined with grasping teeth suggests ram feeding for symmoriiforms, phoebodontids, and xenacanthids [2, 12, 14, 15, 24, 38]. Additionally, the shape of the jaw articulation in Ferromirum gen. nov. revealed a lateral rotation of the Meck-el`s cartilage while the animal was opening and closing its mouth. Therefore, a larger surface of the dentition becomes exposed to the prey, there-by optimizing its predatory success. This partic-ular feeding ecomorphology is unknown from Recent chondrichthyans and might have vanished with the extinction of symmoriiforms. The mor-phology of the visceral skeleton of Ferromirum gen. nov. differs from Palaeozoic chondrichthyans that performed suction prey capture. Early suction feeders such as some hybodontids exhibit reduced teeth, labial cartilages enclosing the mouth and a massive ceratohyal that fl exibly articulates with the mandibular arches as it is involved in the suc-tion movement [16]. In the new symmoriiform portrayed here, labial cartilages are absent and the ceratohyals are slender and closely attached to the jaws (Fig. 4G), which were not suitable for suc-tion feeding.

The discovery of Ferromirum gen. nov. also challenges hypotheses on the arrangement and function of branchial arches in early gnatho-stomes. During the last fi fty years, there was a debate about if whether an aphetohyoidean con-dition in early symmoriiform chondrichthyans existed or not [7, 8, 10, 18, 25, 30]. The apheto-hyoidean hypothesis suggests that the hyoid was not closely attached to the upper jaw and there-fore, the hyoid lacked a suspensory function be-tween the mandibular arch and the braincase [39, 40]. This hypothesis seemed to be supported by a space between the hyoid and the upper jaws in the falcatid Ozarcus mapesae [8]. Accordingly, interpretations of cladoselachians and Cobelodus as a non-aphetohoidean [7, 25] were doubted. The well-preserved branchial and mandibular arches of Ferromirum gen. nov. show that indeed the hyoid was very closely aligned to the mandibular arch without a gap and therefore, the hyoid had a supporting function. This new result falsifi es the aphetohyoidean hypothesis for symmoriiform chondrichthyans.

To conclude, Ferromirum oukherbouchi gen. et sp. nov. is a new symmoriid which refl ects the morphological conservatism of the Symmorii-formes and its well-preserved visceral skeleton shows that the hyoid had a suspensory function, thereby falsifying the aphetohyoidean hypothesis. The reconstruction of the exceptionally preserved upper and lower jaws provide fi rst evidence for the jaw function in symmoriiform chondrich-thyans. As jaw function (subtle rotation of the lower jaws) is unknown from any other Palaeo-

147

Chapter IV: Functional Morphology of Symmoriid Jaws

zoic (and probably Recent) chondrichthyan so far, these fi ndings signifi cantly improve the knowl-edge about the ecomorphological diversity of their early relatives.

4. Material and methods

4.1 Specimen and anatomical reconstruction

based on computered tomograms

The here described specimen (PIMUZ A/I XXXX) of Ferromirum oukherbouchi gen. et sp. nov. is housed at the Palaeontological Institute and Museum of the University of Zurich, Swit-zerland. The specimen was prepared out of a fer-ruginous reddish nodule (rich in haematite) from the Famennian (Late Devonian) of Madene El Mrakib in the Maïder region of the southeastern Anti-Atlas (Morocco).

The specimen was CT-scanned using an indus-trial computer tomography scanner (Nikon XT H 225 ST) at the University of Zurich, Switzerland. Data acquisition and image reconstruction param-eters are: 224 kV, 474μA; fi lter: 4mm of copper; voxel sizes in mm: x = 0.091, y= 0.091, z = 0.091; 16-bit TIFF images were acquired; 8-bit TIFF im-ages were used for reconstruction.

Reconstruction of the 3D model was performed using Mimics v.17 (http://www.biomedical.ma-terialise.com/mimics; Materialise, Leuven, Bel-gium) and the reconstructed 3D-object was edited (smoothing, colours and lightning) in MeshLab v. 2016 (http://www.meshlab.net; [41]) and blend-er v2.79b (https://www.blender.org; Amsterdam, Netherlands). 3D prints of the palatoquadrates and Meckel`s cartilages were made to reconstruct jaw biomechanics of this early chondrichthyan.

For the phylogenetic analysis, the data ma-trix of Frey et al. [27] was used. This matrix is based on gnathostome data matrices of Coates et al. [9, 17] and Brazeau [42], which contains data on Acanthodii published by Davis et al. [43] and Burrow et al. [44] and data on the outgroup from Zhu et al. [45] and Qiao et al. [46]. 228 characters, 66 ingroup taxa and one outgroup taxon (Entelo-gnathus) were included in this data matrix. TNT 1.5 (Tree Analysis Using New Technology [41]) was used to perform phylogenetic analyses via heuristic parsimony analysis (traditional search in TNT) using 10000 multiple random addition sequences and swapping algorithm: tree bisection reconnection (TBR) with 10 trees saved per rep-lication. The data was resampled by using 1000

bootstrap replicants (standard bootstrap and tra-ditional search options in TNT 1.5) and Bremer support retaining trees suboptimal by 5 steps was performed for calculating the nodal supports.

Acknowledgments

General: We are deeply indebted to Saïd Oukhar-bouch (Tafraoute, Morocco) who discovered the holotype and who supported us during fi eld work.

The holotype was prepared by the team of the Tahiri Museum of Fossils and Minerals (Erfoud, Morocco). Anita Schweizer (Zurich) and Alexan-dra Wegemann (University of Zurich) kindly ac-quired CT-scans for us. Many thanks to Thodoris Argyriou (University of Zurich) who helped seg-menting the image stack.

Funding: The project (number S-74602-11-01) was fi nancially supported by the Swiss National Science Foundation.

Author contributions: L.F.: segmentation of computer tomographs, preparing fi gures, drafting manuscript. C.K., M.C., L.F., creating the project. C.K.: photography. M.C.: 3D-printing, interpreta-tion of 3D-models. All authors contributed to the text.

Competing interests: The authors declare no competing interests.

Data and materials availability: In preparation.

References

1. G. R. DeBeer, The Development of the Vertebrate Skull (Univ. Chicago, 1937).

2. R. L. Carroll, Vertebrate paleontology and evolution (W. H. Freeman and Company, New York, 1988).

3. P. Janvier, Early Vertebrates (Oxford Univ. Press, 1996)

4. J. Mallat, Ventilation and the origin of jawed verte-brates: a new mouth. Zool. J. Linn. Soc. 117, 329-404 (1996).

5. S. Kuratani, Evolution of the vertebrate jaw from developmental perspective. Evol. Dev. 14, 76-92 (2012).

6. S. Kuratani, N. Adachi, N. Wada, Y. Oisi, F. Sugaha-ra, Developmental and evoultionary signifi cance of the mandibular arch and prechordal/preman-dibular cranium in vertebrates: revising the heterotopy scenario of gnathostome jaw evolution. J. Anat. 222, 41-55 (2013).

148

Chapter IV: Functional Morphology of Symmoriid Jaws

7. J. G. Maisey, Visceral skeleton and musculature of a Late Devonian shark. J. Vertebr. Paleon-tol. 9, 174–190 (1989).

8. A. Pradel, J. G. Maisey, P. Tafforeau, R. H. Mapes, J. Mallatt, A Palaeozoic shark with osteichthyan-like branchial arches. Nature 509, 608-611 (2014).

9. M.I. Coates, J.A. Finarelli, I.J. Sansom, P.S. An-dreev, K.E. Criswell, K. Tietjen, M.L. Rivers, P.J. La Riviere, An early chondrichthyan and the evo-lutionary assembly of a shark body plan. Proc. R. Soc. Lond., B, Biol. Sci. 285: 20172418. (2018) http://dx.doi.org/10.1098/rspb.2017.2418

10. R. Zangerl, Handbook of Paleoichthyology: Chon-drichthyes I, Paleozoic Elasmobranchii, H.P. Schul-tze, Ed. (Gustave Fischer, Stuttgart, New York, 1981), vol. 3A.

11. R. E. Plotnick, T. K. Baumiller, Invention by evolu-tion: functional analysis in paleobiology. Pa-leobiology 26(4), 305-323.

12. E.D. Grogan, R. A Lund, basal elasmobranch, Thr-inacoselache gracia n. gen & sp., (Thrinacodonti-dae, new family) from the Bear Gulch Limestone, Serpukhovian of Montana, USA. J Vertebr. Paleon-tol. 28(4), 970–988 (2008).

13. M. Ginter, Devonian fi lter-feeding sharks. Acta Geol. Pol. 58(2), 147-153 (2008).

14. M. Ginter, O. Hampe, C. J. Duffi n, Handbook of Paleoichthyology: Chondrichthyes, Paleozoic Elas-mobranchii, teeth, H.P. Schultze, Ed. (Verlag Dr. Friedrich Pfeil, München, 2010) vol. 3D.

15. L. Frey, M.I. Coates, M. Ginter, V. Hairapetian, M. Rücklin, I. Jerjen, C. Klug, Morphology, phyloge-netic relationships and ecomorphology of the early elasmobranch Phoebodus (in preparation).

16. J. G. Maisey, Cranial anatomy of Hybodus basanus Egerton from the Lower Cretaceous of England. Am. Mus. Novit. 2758, 1–64 (1983).

17. M. I. Coates, R. W. Gess, J. A Finarelli, K. E Criswell, K. A. Tietjen, symmoriiform chondrich-thyan braincase and the origin of chimaeroid fi shes. Nature 541, 209-211 (2017).

18. R. Zangerl, G. R. Case, Cobelodus aculeatus (Cope), an anacanthous shark from Pennsylvanian Black Shales of North America. Palaeontographi-ca A 154, 107–57 (1976).

19. R. Lund, Stethacanthid elasmobranch remains from the Bear Gulch Limestone (Namurian E2b) of Montana. Am. Mus. Novit. 2828, 1–24 (1985a).

20. R. Lund, The morphology of Falcatus falcatus (St. John and Worthen), a Mississippian stethacanthid chndrichthyan from the Bear Gulch Limestone of Montana. J. Vert. Paleontol. 5, 1-19 (1985b).

21. R. Lund, On Damocles serratus nov. gen. et sp., (Elasmobranchii: Cladodontida) from the Upper Mississippian Bear Gulch Limestone of Montana. J. Vert. Paleontol. 6, 12-19 (1986).

22. Williams, M. E. The ‘‘cladodont level’’ sharks of the Pennsylvanian Black Shales of central North America. Palaeontographica A 190, 83–158

(1985).23. M. I. Coates, S. E. K. Sequeira, The braincase of a

primitive shark. Trans. R. Soc. Edinb. (Earth Sci.) 89, 63–85 (1998).

24. M. I. Coates, S. E. K. Sequeira, A new stethacan-thid chondrichthyan from the Lower Carboniferous of Bearsden, Scotland. J. Vertebr. Paleontol. 21, 754–766 (2001).

25. J. G. Maisey, The braincase in Paleozoic symmo-riiform and cladoselachian sharks. Bull. Am. Mus. Nat. Hist. 307, 1–122 (2007).

26. A. Pradel, P. Tafforeau, J. G. Maisey, P. A. Janvier, New Paleozoic Symmoriiformes (Chondrichthy-es) from the Late Carboniferous of Kansas (USA) and Cladistic Analysis of Early Chondrichthyans. PLoS ONE 6: e24938 DOI:10.1371/journal.pone.0024938 (2011).

27. L. Frey, M. Rücklin, D. Korn, C. Klug, Late Devo-nian and Early Carboniferous alpha diversity, ecospace occupation, vertebrate assemblages and bio-events of southeastern Morocco. Palae-ogeogr. Palaeoclimatol. Palaeoecol. 496, 1-17 (2018).

28. B. Schaeffer, The xenacanth shark neurocranium, with comments on elasmobranch monophyly. Bull. Am. Mus. Nat. Hist. 169, 1–66 (1981).

29. Hotton, N. Jaws and teeth of American xenacanth sharks. J. Paleontol. 26, 489-500 (1952).

30. R. Zangerl, M.E. Williams. New evidence of the nature of the jaw suspension in Palaeozoic anacan-thus sharks. Palaeontology 18, 333.341 (1975).

31. J. R., Dick. On the Carboniferous shark Tristychius arcuatus Agassiz from Scotland. Earth Environ Sci Trans R Soc Edinb. 70(4), 63-108 (1978).

32. G. J. Nelson, Gill arches and the phylogeny of fi sh-es, with notes on the classifi cation of vertebrates. Bull. Am. Mus. Nat. Hist. 141, 475–552 (1969).

33. B. Dean, Studies on fossil fi shes (sharks, chimae-roids and arthrodires. Memoirs of the AMNH 9(5), 209-287 (1909C).

34. U. H. J. Heidtke , C. Schwind, Über die Organisa-tion des Skelettes der Gattung Xenacanthus (Elas-mobranchii: Xenacanthida) aus dem Unterperm des südwestdeutschen Saar-Nahe-Beckens. Neu-es Jahrb. Geol. Paläontol. Abhl. 231(1), 85–117 (2004).

35. U. H. J. Heidtke, C. Schwind, K. Krätschmer, Über die Organisation des Skelettes und die ver-wandschaftlichen Beziehungen der Gattung Trio-dus Jordan 1849 (Elasmobranchii: Xenacanthida). Mainzer geowiss. Mitt. 32, 9-54 (2004).

36. J. E. Harris, The dorsal fi n spine of Cladoselache. Sci. publ. Clevel. Mus. Nat. Hist. 8, 1-6 (1938a).

37. P. J. Motta, Prey capture behavior and feeding me-chanics of elasmobranchs. In Biology of sharks and their relative, P.L. Lutz, Ed. (CRC Press. 2004), pp. 245-301.

38. R. Lund, E. D. Grogan, Relationships of the Chi-maeriformes and the basal radiation of the Chon-

149

Chapter IV: Functional Morphology of Symmoriid Jaws

drichthyes. Rev. Fish Biol. Fish 7, 65-123 (1997). 39. C. Gegenbaur, Untersuchungen zur vergleichenden

Anatomie der Wirbelthiere. III. Das Kopfskelet der Selachier, ein Beitrag zur Erkenntniss der Gene-se des Kopfskeletes der Wirbelthiere (Engelmann, Leipzig, 1872).

40. D. M. S. Watson, The acanthodian fi shes. Philos. Trans. Royal Soc. B 228, 49-146 (1937).

41. P. Cignoni, M. Callieri, M. Corsini, M. Dellepiane, F. Ganovelli, G. Ranzuglia, MeshLab: an Open-Source Mesh Processing Tool. Sixth Eurographics Italian Chapter Conference, 129-136 (2008).

42. M. D. Brazeau, The braincase and jaws of a De-vonian acanthodian and modern gnathostome ori-gins. Nature 457, 305-308 (2009). (doi: 10.1038/nature07436)

43. S.P. Davis, J.A. Finarelli, M.I. Coates, Acanthodes

and shark-like conditions in the last common an-cestor of modern gnathostomes. Nature 486, 247-250 (2012). (doi:10.1038/nature11080)

44. C.J. Burrow, J. den Blaauwen, M. Newman, R. Davidson, The diplacanthid fi shes (Acanthodii, Di-placanthiformes, Diplacanthidae) from the Middle Devonian of Scotland. Palaeontol. Electron. 19, 1-83 (2016).

45. M. Zhu, X. Yu, P.E. Ahlberg, B. Choo, J. Lu, Q.L. Qiao, J. Zhao, H. Blom, Y. Zhu. A, Silurian plac-oderm with osteichthyan-like marginal jaw bones. Nature 502, 188-193 (2013). (doi:10.1038/na-ture12617)

46. T. Qiao, B. King, J.A. Long, P.E. Ahlberg, M. Zhu, Early gnathostome phylogeny revisited: multi-ple method consensus. PLoS ONE 11, e0163157 (2016). (doi:10.1371/journal.pone.0163157)

150

Chapter IV: Functional Morphology of Symmoriid Jaws

Entelognathus

Youngolepis

Guiyu

Psarolepis

Cheirolepis

Mimipiscis

Raynerius

Moythomasia

Culmacanthus

Ischnacanthus

Nerepisacanthus

Poracanthodes

Tetanopsyrus

Uraniacanthus

Diplacanthus

Rhadinacanthus

Cassidiceps

Mesacanthus

Promesacanthus

Cheiracanthus

Acanthodes

Homalacanthus

Halimacanthodes

Gladbachus

Brachyacanthus

Brochoadmones

Climatius

Parexus

Ptomacanthus

V waynensis

Gyracanthides

Latviacanthus

Pucapampella

Kathemacanthus

Lupopsyrus

Obtusacanthus

Doliodus

Acronemus

Egertonodus

Hamiltonichthys

Onychoselache

Tribodus

Squalus

Synechodus

Tristychius

Homalodontus

Cladodoides

Phoebodus

Thrinacodus

Diplodoselache

Orthacanthus

Triodus

Tamiobatis

Dwykaselachus

Ozarcus

Cladoselache

Cobelodus

Akmonistion

Damocles

Falcatus

Debeerius

Chimaeroidei

Chondrenchelys

Helodus

Iniopera

Kawichthys

Ferromirum gen. nov

5/100

5/87

5/93

5/95

3/7965

5/99

2/62

4

258

5/85

5/71

5/66

4

2

3

4/52

2/54

3/94

2

2/544/83

Fig

. S

1. S

tric

t con

sens

us tr

ee in

clud

ing

valu

es o

f B

rem

er`s

dec

ay a

nd b

oots

trap

sup

port

at s

pecifi

c kn

ots.

Col

our

codi

ng: b

lack

, ste

m g

roup

gna

thos

tom

e (o

utgr

oup)

; gre

en,

Ost

eich

thye

s; r

ed, A

cant

hodi

i (s

tem

Cho

ndri

chth

yes)

; or

ange

, ste

m C

hond

rich

thye

s ex

clud

ing

Aca

ntho

dii;

blu

e, E

lasm

obra

nchi

i (c

row

n C

hond

rich

thye

s);

purp

le, H

olo-

ceph

ali

(cro

wn

Cho

ndri

chth

yes)

. B

rem

er s

core

s: 3

, go

od s

uppo

rt;

5, h

ighl

y su

ppor

ted.

Boo

stra

p va

lues

: m

ore

than

50:

wea

k su

ppor

t, m

ore

than

75;

goo

d su

ppor

t; 1

00:

high

est s

uppo

rt.

SUPPLEMENTARY FIGURE

151

Chapter IV: Functional Morphology of Symmoriid Jaws

Supplementary material

2. Taxa and sources

Acanthodes: Beznosov 2009; Brazeau & de Winter 2015; Coates 1994; Davis et al. 2012; Heidtke 1993, 2011a,b; Jarvik 1977, 1980; Miles 1968, 1973a, b; Nelson 1968; specimens AMNH 1037b, 10370, 10376, 19628; CMNH 30725b, 30726, 4591; FMNH PF2875; GM C145, 146, 180; HM V8251, 252; HU MB.F.4209, 4277, 4284, 4285, 7286, MB3b, 4a & b, 5a & b, 7a & b, 8a & b, 11a & b, 12a, 13a &b, 14a &b, 16a &b, 17a & b, 18a & b, 23 (resin copy), 24, MM L1693, 1698, 9432B, W1994; NHM P.11287, P.13139, 13140, 14558, 1728, 34912, 34914, 4057, 49941, 49944, 49959, 49967, 49979, 49980, 49990, 49995, 49996, 60928, 60939, 62138, 7335; NMS 2001.7.1, 3; UCL GM C1126; UMZC GN9, 11, 13, 14, 15a &b, 16, 39, 756.

Acronemus: Maisey 2011; Rieppel 1982.Akmonistion: Coates & Sequiera 1998, 2001a, b; Coates et al. 1998; Coates et al. 2017.Brachyacanthus: Denison 1979; Miles 1973a; Watson 1937; specimens NMS Kinnaird 88, NMS (Powrie)

1891.92.212, 213, 214, 220, 222, 224, 225, 226, 227.Brochoadmones: Bernacsek & Dineley 1977; Gagnier & Wilson 1996b; Hanke & Wilson 2006; specimens

UALVP 32672, 41487, 41493, 41494, 41495.Callorhinchus/Hydrolagus: Cole 1896; De Beer 1937; De Beer & Moy-Thomas 1935; Didier 1995; Didier

et al. 1994, 2012; Howard et al. 2013; Kesteven 1937; Patterson 1965, 1992; Pradel et al. 2013; Stahl 1999.

Cassidiceps: Gagnier & Wilson 1996a; specimen UALVP 32454.Cheiracanthus: Denison 1979; Miles 1973a; Watson 1937; specimens AMNH 317, 6929, 7082; GM C295,

296, 325, 490; HM V7614; IC 214, 215, 216, 217; UMZC GN14a &b, 19, 20, 21, 31, 50; 1131a & b, 1132a & b, 1133a & b, 1134a & b, 1135a & b, 1136a & b, 1137a & b, 1138, 1139, 1140.

Cheirolepis: Arratia & Cloutier 1996; Pearson & Westoll 1979; Giles et al. 2015a.Chondrenchelys: Finarelli & Coates 2012, 2014; Lund 1982; Moy-Thomas 1935; specimens NMS

1885.54.5/5A, 1891.53.33, 1998.35.1, 2002.68.1; BGS-GSE 13328; HM V.7173.Cladodoides: Gross 1937, 1938; Maisey 2005.Cladoselache: Bendix-Almgreen 1975; Harris 1938a, b; Maisey 1989a, 2007; Schaeffer 1981; Williams

2001; Woodward & White 1938; specimens CMNH 8110, 8111, 8207, NHM P9273, P9285.Climatius: Miles 1973a, b; Watson 1937: specimens AMNH 7762; GSM 49785; MM L12096a & b; NMS

Kinnaird 80; NMS 1881.5.62; NMS 1887 (Peach) 35.3a, 35.5b, 35.5e; NMS 1891 (Powrie) 92.195, 204, 206, 214; NMS 1967.12.4; NMS 1973.9.4; NMS 2001.7.2.

Cobelodus: Zangerl & Case 1976; Zidek 1992.Culmacanthus: Long 1983.Damocles: Lund 1986: specimens CM 35472, 48760.Debeerius: Grogan & Lund 2000: specimens CM 35479, 35480, 48831, 62811.Ferromirum oukherbouchi gen. et sp. nov.: holotype specimen PIMUZ XX.Diplacanthus: Gagnier 1996; Miles 1973a; Watson 1937; specimens FMNH PF11633; GM C12, 13, 148;

GM P482; MM L5503, 1609; NMS (Powrie) 1891.92.334; NMS 2001.7.4; UMZC GN17, 18, 22.Diplodoselache: Dick 1981.Doliodus: Miller et al. 2003; Maisey et al. 2009, 2013, 2017; Long et al. 2015.Dwykaselachus: Coates et al. 2017; Oelofsen 1986; specimen SAM K5840.Egertonodus: Maisey 1982, 1983; Lane, 2010.Entelognathus: Zhu et al. 2013.Falcatus: Lund 1985; Maisey 2007; specimens CM 35465, 37532.Gladbachus: Heidtke & Krätschmer 2001; Heidtke 2009; Burrow & Turner 2013; specimen UMZC

2000.32.Guiyu: Zhu et al. 2009.Gyracanthides: Miles 1973a; Warren et al. 2000; Turner et al. 2005.Halimacanthodes: Burrow et al. 2012.Hamiltonichthys: Maisey 1989b.Helodus: Patterson 1965; Stahl 1999; specimens NHM P.6706, 8207, 8209, 8212, 8213.Homalacanthus: Gagnier 1996; Watson 1937; specimens FMNH PF4875; MM LL12452.Homalodontus: Mutter et al. 2007, 2008.

152

Chapter IV: Functional Morphology of Symmoriid Jaws

Iniopera: Zangerl & Case 1973; Pradel et al. 2009, Pradel 2010; Pradel et al. 2010.Ischnacanthus; Miles 1973a; Watson 1937; specimens GM C3, 6, 149, 324; GM P298; MM L9522, 9431,

9432; MM STR0585; NMS (Powrie) 92.254, 258; UALVP 32401, 32405, 32414, 39060, 39075, 40478, 41491, 41861, 42201, 42215, 42660, 43245, 44048, 44049, 44091, 45014.

Kathemacanthus: Gagnier & Wilson 1996a; Hanke & Wilson 2010; specimens UALVP 32402, 42269, 43113.

Kawichthys: Pradel et al. 2011.Latviacanthus: Schultze & Zidek 1982.Lupopsyrus: Hanke & Davis 2012; Bernacsek & Dineley 1977; specimens NMC 22700B, 22700C, 22715,

22718, 22719, 22700D, 22700E, 22700F, 22701C, 22701D, 22716, 22717, 22720, 22745; UALVP 19260, 32420, 32442, 32456, 32458, 32474, 32476, 32480, 32482, 39065, 39067, 39079, 39080, 39081, 39082, 39121, 41493, 41629, 41632, 41665, 41931, 41939, 41945, 42000, 42002, 42008, 42012, 42013, 42027, 42046, 42061, 42113, 42142, 42150, 42173, 42208, 42274, 42518, 42524, 42529, 42530, 42533, 42538, 42453, 42454, 42455, 42544, 42597, 42605, 43064, 43091, 43092, 43094, 43095, 43256, 43409, 43456, 45154, 45155.

Mesacanthus: Miles 1973a; Watson 1937; specimens FMNH PF1439; GM C18, 288a &b; NMS (Powrie) 1891.92.275; UMZC GN1143.

Mimipiscis: Gardiner & Bartram 1977; Gardiner 1984; Choo 2011; Giles & Friedman 2014.Moythomasia: Gardiner & Bartram 1977; Gardiner 1984; Coates et al. 2017; specimen MV P222915.Nerepisacanthus: Burrow 2011; Burrow & Rudkin 2014.Obtusacanthus: Hanke & Wilson 2004; specimen UALVP 41488.Onychoselache: Dick & Maisey 1980; Coates & Gess 2007.Orthacanthus: Heidtke 1982, 1999; Hotton 1952; Schaeffer 1981; Maisey 1983; Lane & Maisey 2009.Ozarcus and FMNH PF 13242: Maisey 2007; Pradel et al. 2014; Coates et al. 2017.Parexus: Watson 1937; Miles 1973a. specimens AMNH 1163, 7766; NMS Kinnaird 94; NMS (Peach)

1887.35.3a, 5e; NMS 1891 (Powrie) 92.183, 184, 186, 188, 194, 197, 207; NMS 1956.14.4.15; NMS 1977.46.3a & b.

Phoebodus: Newberry 1889; Ginter 1990; Ginter & Ivanov 1992, 1995; Ginter et al. 2002; Ginter et al. 2010; specimen PIMUZA/I 4656, PIMUZ A/I 4710, PIMUZ A/I 4712, PIMUZ A/I 4711, PIMUZ A/I 4713.

Poracanthodes: Denison 1979; Valiukevicius 1992. Promesacanthus: Hanke 2008; specimens UALVP 41672, 41859, 41860, 42652, 43027.Psarolepis: Yu 1998; Zhu & Schultze 1997; Zhu et al. 1999; Qu et al. (2013).Ptomacanthus: Brazeau 2009, 2012; Denison 1979; Miles 1973a; specimens BM P.19999, 24919b.Pucapampella: Maisey 2001a; Maisey & Anderson 2001; Maisey & Lane 2010; Janvier & Maisey 2010.Raynerius: Giles et al. 2015b.Rhadinacanthus: Burrow et al. 2016.Squalus: Schaeffer 1981; Gans & Parsons 1964; Marinelli & Strenger 1959.Synechodus: Maisey 1985; NHM P.6135, 41675.Tamiobatis: Eastman 1897A; Schaeffer 1981; Williams 1998; specimen FMNH PF5414.Tetanopsyrus: Gagnier & Wilson 1995; Gagnier et al. 1999; Hanke et al. 2001; specimens UALVP 32571,

38682, 39062, 39078, 42512, 43026, 43246, 44030, 43089.Thrinacodus: Turner 1982; Ginter 2000; Ginter & Sun 2007; Ginter & Turner 2010; Ginter et al. 2010;

Grogan & Lund 2008. Tribodus: Maisey & de Carvalho 1997; Lane 2010; Lane & Maisey 2009, 2012.Triodus: Solér-Gijon & Hampe 1998; Hampe 2003; Heidtke et al. 2004.Tristychius: Dick1978; Coates & Gess 2007; Coates & Tietjen 2018. Uraniacanthus: Bernacsek & Dineley 1977; Hanke & Davis 2008; Newman et al. 2012; Burrow et al.

2016; specimens UALVP 19259, 32448, 32469, 38679, 41669, 41857, 41858, 41862, 42095, 42095, 44046, 45366 to 45396.

Vernicomacanthus waynensis: Miles 1973a.Youngolepis: Chang & Yu 1981; Chang 1982, 1991, 2004.

153

Chapter IV: Functional Morphology of Symmoriid Jaws

3. Character list

Skeletal tissues1 Tessellate calcifi ed cartilage: absent (0); present (1). Brazeau (2009); Coates & Sequeira (2001a, b);

Davis et al. (2012); Dean & Summers (2006); Dean et al. (2009); Grogan et al. (2012); Maisey (1984, 2001, 2013); Lund & Grogan (1997, 2004a, b); Seidel et al. (2016).

2 Perichondral bone: present (0); absent (1). Janvier (1996); Donoghue & Aldridge (2001); Brazeau (2009); Davis et al. (2012); Lund (1985); Coates et al. (1999).

3 Extensive endochondral ossifi cation: absent (0); present (1). Forey (1980); Gardiner (1984); Brazeau (2009); Davis et al. (2012).

4 Extensive calcifi ed cartilage: absent (0); present (1). Coates et al. (2018). 5 Dentine kind: mesodentine or semidentine (0); orthodentine (1). Donoghue et al. (2000); Brazeau

(2009); Davis et al. (2012); Burrow et al. (2016) 6 Pore canal network: absent (0); present (1). Lu et al. (2016).7 Acrodin tooth caps (enameloid cap restricted to crown apex): absent (0); present (1). Friedman &

Brazeau (2010); Zhu et al. (2009, 2013); Lu et al. (2016).

Squamation & related structures8 Trunk scales monocuspid (0); multicuspid (1). Revised after Davis et al. (2012); Burrow et al.

(2016). 9 Scale growth concentric: absent (0); present (1). Hanke & Wilson (2004); Brazeau (2009); Davis

et al. (2012); Burrow et al. (2016).10 Peg-and-socket articulation: absent (0); present (1). Gardiner (1984); Coates (1999); Brazeau

(2009); Davis et al. (2012).11 Anterodorsal process on scale: absent (0); present (1). Zhu et al. (2009, 2013); Gardiner (1984);

Coates (1999); Brazeau (2009); Davis et al. (2012).12 Body scales with bulging base: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Burrow

et al. (2016). 13 Body scales with fl attened base: absent (0); present (1). Brazeau (2009, 2012); Davis et al. (2012);

Burrow et al. (2016). 14 Body scales with basal canal or open basal vascular cavity: absent (0); present (1). Reif (1978);

Coates & Sequeira (2001a); Young (1982). 15 Neck canal: absent (0) present (1). Coates et al. (2017).16 Sensory line canal passes between or beneath scales (0); passes over scales and/ or is partially

enclosed or surrounded by scales (1); perforates and passes through scales (2). Davis (2002); Friedman & Brazeau (2010); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014); Burrow et al. (2016).

17 Lepidotrichia or lepidotrichia-like scale alignment: present (0); absent (1). Davis et al. (2012).18 Epichordal lepidotrichia: absent (0); present (1). Zhu et al. (2009, 2013).19 Fringing fulcra: absent (0); present (1). Zhu et al. (2009, 2013); Coates (1999).20 Scute-like ridge scales (fulcra): absent (0); present (1). Giles et al. (2015c).

Cranial dermal skeleton21. Sclerotic ring: absent (0); present (1). Giles et al. (2015c); Qiao et al. (2016); Zhu et al. (2016);

Burrow et al. (2016). 22 Number of sclerotic plates: four or less (0); more than four (1). Zhu et al. (2013, c170); Qiao et al.

(2016, c.241); Zhu et al. (2016, c.239); Burrow et al. (2016). 23 Dermal ornamentation: smooth (0); parallel, vermiform ridges (1); concentric ridges (2); tuber-

culate (3). Giles et al. (2015c).24 Dermal skull roof includes large dermal plates (0); consists of undifferentiated plates, tesserae

or scales (1); naked or largely scale free (2). Forey (1980); Gardiner (1984); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).

25 Cranial tessera morphology: large interlocking plates (0); microsquamose, no larger than body

squamation (1). Brazeau (2009) through to Giles et al. (2015c).26 Anterior or mesial edge of nasal notched for anterior nostril: absent (0); present (1). Contra Zhu

et al. (2013), the anterior rim of the nasal in Cheirolepis is notched.

154

Chapter IV: Functional Morphology of Symmoriid Jaws

27 Supraorbital: absent (0); present (1). Zhu et al. (2009, 2013).28 Large median bone contributes to posterior margin of skull roof: absent (0); present (1). Zhu et

al. (2016).29 Medial process of paranuchal wraps around posterolateral corners of nuchal plate: absent (0);

present (1); paranuchals precluded from nuchal by centrals (2); no median bone in posterior of

skull roof (3). Giles et al. (2015c).30 Pineal opening perforates dermal skull roof: present (0); absent (1). Davis et al. (2012); Giles et

al. (2015c).31 Consolidated cheek plates: absent (0); present (1). Davis (2002); Brazeau (2009); Davis et al.

(2012); Zhu et al. (2013); Burrow et al. (2016).32 Enlarged postorbital tessera separate from orbital series: absent (0); present (1). Brazeau (2009);

Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).33 Dermal intracranial joint: absent (0); present (1). Zhu et al. (2009, 2013)34 Foramina (similar to infradentary foramina) on cheek bones: absent (0); present (1). Zhu et al.

(2009, 2013).35 Preopercular bone: absent (0); present (1). Zhu et al. (2013).36 Maxilla expanded posteriorly: absent - splint shaped (0); present - cleaver shaped (1). Zhu et al.

(2009, 2013); Lu et al. (2016).37 Sensory line network preserved as open grooves (sulci) in dermal bones (0); sensory lines pass

through canals enclosed within dermal bones (1). (Davis 2002); Davis et al. (2012); Zhu et al. (2013).

38 Sensory canal or pit-line associated with maxilla: absent (0); present (1). Friedman (2007) 39 Jugal portion of infraorbital canal joins supramaxillary canal: present (0); absent (1). Brazeau

(2009), but see redefi nition in Davis et al. (2012); Zhu et al. (2013).40 Anterior pit line of skull roof: absent (0); present (1). Giles et al. (2015c).41 Spiracular opening in dermal skull roof bounded by bones carrying otic canal: absent (0); pres-

ent (1). Giles et al. (2015); Lu et al. (2016).42 Endolymphatic ducts open in dermal skull roof: present (0); absent (1). Janvier (1996); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013); Giles et al. (2015c). 43 Dermohyal (submarginal) ossifi cation: absent (0); present (1). 44 Dermohyal (submarginal) shape: broad plate that tapers towards its proximal end (0); narrow

plate (1). Brazeau’s (2009)45 Branchiostegal series: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).46 Opercular and subopercular bones: absent (0); present (1).

47 Branchiostegal plate series along ventral margin of lower jaw: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

48 Branchiostegal ossifi cations plate-like (0); narrow and ribbon-like (1); fi lamentous (2). Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Lu et al. (2016).

49 Branchiostegal ossifi cations ornamented (0); unornamented (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

50 Branchiostegals imbricated: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

51 Opercular cover of branchial chamber complete or partial (0); separate gill covers and gill slits

(1). Lund & Grogan (1997); Hanke & Wilson (2004); Davis et al. (2012); Zhu et al. (2013). 52 Gular plates: absent (0); present (1). Gardiner (1984); Brazeau (2009); Davis et al. (2012); Zhu et

al. (2013).53 Size of lateral gular plates: extending most of length of the lower jaw (0); restricted to the anteri-

or third of the jaw (no longer than the width of three or four branchiostegals) (1). Coates (1999); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

Hyoid and gill arches154 Gill skeleton mostly beneath otico-occipital region (0); mostly posterior to occipital region (1).

Zangerl (1981); Lund & Grogan (1997); Stahl (1999). 55 Perforate hyomandibula: absent (0); present (1). Zhu et al. (2009, 2013); Lu et al. (2016).56 Interhyal: absent (0); present (1). Davis et al. (2012); Zhu et al. (2013).

155

Chapter IV: Functional Morphology of Symmoriid Jaws

57 Ceratohyal smooth with posterior, lateral fossa: absent (0); present (1). Coates et al. (2018). 58 Ceratohyal anteriorly blade-shaped: absent (0), present (1). Frey et al. (in prep.). Tristychius and

Phoebodus exhibit ceratohyals with an anteriorly derived shape. 59 Hypohyals: absent (0); present (1). Friedman & Brazeau (2010); Pradel et al. (2014). 60 Basihyal absent, hyoid arch articulates directly with basibranchial (0); basihyal present (1).

Pradel et al. (2014); see also discussion in Carr et al. (2009); Brazeau et al. (2017). 61 Separate supra- and infra-pharyngobranchials absent (0); present (1). Gardiner (1984); Pradel et

al. (2014). 62 Pharyngobranchials directed anteriorly (0); posteriorly (1). Pradel et al. (2014). 63 Posteriormost branchial arch bears epibranchial unit: absent (0); present (1). Coates et al.

(2018). Absent in osteichthyans; present in chondrichthyans, Gladbachus and Acanthodes (Davis et al. 2012; Pradel et al. 2014).

64 Epibranchials bear posterior fl ange: absent (0); present (1). Coates et al. (2018). 65 Hypobranchials directed anteriorly (0); hypobranchials of second and more posterior gill arches

directed posteriorly (1). Coates et al. (2018).

Dentition & tooth-bearing bones and cartilages66 Oral dermal tubercles borne on jaw cartilages: absent (0); present (1). Hanke & Wilson (2004);

Brazeau (2009); Davis et al. (2012); Zhu et al. (2013). 67 Pharyngeal teeth or denticles: absent (0); present (1). Coates et al. (2017, 2018). 68 Tooth families/ whorls: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013).69 Bases of tooth families/ whorls: single, continuous plate (0); some or all whorls consist of sepa-

rate tooth units (1). Adjusted by Coates et al. (2018) from Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Giles et al. (2015).

70 Lingual torus: absent (0); present (1). After Ginter et al. 2010; Coates et al. (2018). 71 Basolabial shelf: absent (0); present (1). Coates et al. (2017), after Ginter et al. (2010) 72 Tooth families/whorls restricted to symphysial region (0); distributed along jaw margin (1).

Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013). 73 Number of tooth families/whorls per jaw ramus: 15 or fewer (0); 20 or more (1). Coates et al.

(2018). 74 Toothplates absent (0); present (1). Follows defi nition of Coates et al. (2018). 75 Toothplate complement restricted to two pairs in the upper jaw and a single pair in the lower

jaw: absent (0); present (1). After Patterson (1965); Coates et al. (2018).76 Mandibular teeth fused to dermal plates on biting surfaces of jaw cartilages: absent (0); present

(1). Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013). 77 Dermal plates on biting surface of jaw cartilages: absent (0); present (1). Brazeau (2009); Davis

et al. (2012); Zhu et al. (2013); Giles et al. (2015c).78 Gnathal plates mesial to and/ or above (or below) jaw cartilage: absent (0); present (1). Zhu et

al. (2016).79 Maxilla and premaxilla sensu stricto (upper gnathal plates lateral to jaw cartilage without pala-

tal lamina): absent (0); present (1). Zhu et al. (2016).80 Dentary bone encloses mandibular sensory canal: absent (0); present (1). Gardiner (1984) and

references therein; Zhu et al. (2009, 2013).81 Infradentary foramen and groove, series: absent (0); present (1). Zhu et al. (2010).82 Tooth-bearing median rostral: absent (0); present (1). Zhu et al. (2009, 2013).83 Median dermal bone of palate (parasphenoid): absent (0); present (1). Gardiner (1984); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013).84 Denticulated fi eld of parasphenoid: without spiracular groove (0); with spiracular groove (1).

Friedman (2007); Zhu et al. (2009, 2013).85 Denticle fi eld of parasphenoid with multifi d anterior margin: absent (0); present (1). Friedman

(2007); Zhu et al. (2009, 2013); Lu et al. (2016).

Mandibular arch86 Large otic process of the palatoquadrate: absent (0); present (1). Coates & Sequeira (2001a);

Davis (2002); Brazeau (2009); Zhu et al. (2009, 2013).

156

Chapter IV: Functional Morphology of Symmoriid Jaws

87 Oblique ridge or groove along medial face of palatoquadrate: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Lu et al. (2016).

88 Fenestration of palatoquadrate at basipterygoid articulation: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Lu et al. (2016).

89 Perforate or fenestrate anterodorsal (metapterygoid) portion of palatoquadrate: absent (0);

present (1). Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).90 Articulation surface of the palatoquadrate with the postorbital process directed anteriorly (0);

laterally (1); dorsally (2). Coates et al. (2017). 91 Palatoquadrate fused to the neurocranium: absent (0); present (1). Coates et al. (2017).92 Pronounced dorsal process on Meckelian bone or cartilage: absent (0); present (1). Davis (2002);

Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016). 93 Mandibular mesial process: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al.

(2013); Burrow et al. (2016). 94 Jaw articulation located on rearmost extremity of mandible: absent (0); present (1). Davis et al.

(2012); Zhu et al. (2013).195 Dental sulcus (trough) adjacent to oral rim on Meckel’s cartilage and palatoquadrate: absent

(0); present (1). Coates et al. (2017). 96 Scalloped oral margin on Meckel’s cartilage and palatoquadrate: absent (0); present (1). Coates

et al. (2017). Characteristic of some symmoriiform chondrichthyans such as Akmonistion, Ozarcus, and Cladoselache, but also present in Helodus (pers. obs. MIC).

97 Mandibular symphysis fused: absent (0); present (1). Coates et al. (2017).

Neurocranium98 Internasal vacuities: absent (0); present (1). Lu et al. (2016). 99 Precerebral fontanelle: absent (0); present (1). Schaeffer (1981); Lund & Grogan (1997); Coates &

Sequeira (1998, 2001a, b); Maisey (2001a); Brazeau (2009); Pradel et al. (2011) Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).

100 Space for forebrain and (at least) proximal portion of olfactory tracts narrow and elongate, ex-

tending between orbits: absent (0); present (1). Coates et al. (2017).101 Prominent, pre-orbital, rostral expansion of the neurocranium: present (0); absent (1). Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013). 102 Rostral bar: absent (0); present (1). Adapted from Maisey (1985); Coates et al. (2017). 103 Internasal groove absent (0); present (1). Coates et al. (2017); present in Iniopera and Dwykasela-

chus (Pradel 2010).104 Orbitonasal lamina dorsoventrally deep: absent (0); present (1). Patterson (1965); Davis et al.

(2012); Zhu et al. (2013); Coates et al. (2017). 105 Palatobasal (or orbital) articulation posterior to the optic foramen (0); anterior to the optic

foramen, grooved, and overlapped by process or fl ange of palatoquadrate (1); anterior to optic

foramen, smooth, and overlaps or fl anks articular surface on palatoquadrate (2). Adapted by Coates et al. (2018) from Pradel et al. (2011, character 26), Coates et al. (2017, character 71) and Maisey (2005, p.61)

106 Trochlear nerve foramen anterior to optic nerve foramen: absent (0); present (1). Coates & Se-queira (2001).

107 Supraorbital shelf broad with convex lateral margin: absent (0); present (1). Coates & Sequeira (1998); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

108 Orbit directed mostly laterally and free of fl anking endocranial cartilage or bone: absent (0);

present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Coates et al. (2018). 109 Interorbital space broad (0); narrow (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013);

Coates et al. (2017).110 Optic pedicel: absent (0); present (1). Dupret et al. (2014); Zhu et al. (2009, 2013); Coates et al.

(2017).111 Ophthalmic foramen in anterodorsal extremity of orbit communicates with cranial interior:

absent (0); present (1). Coates et al. (2017).112 Extended prehypophysial portion of sphenoid: absent (0); present (1). Brazeau (2009); Davis et

al. (2012); Zhu et al. (2013).113 Canal for efferent pseudobranchial artery within basicranial cartilage: absent (0); present (1).

157

Chapter IV: Functional Morphology of Symmoriid Jaws

Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).114 Entrance of internal carotids: through separate openings fl anking the hypophyseal opening or

recess (0); through a common opening at the central midline of the basicranium (1). Schaeffer (1981); Coates & Sequeira (1998); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

115 Internal carotids: entering single or paired openings in the basicranium from a posterolateral

angle (0); entering basicranial opening(s) head-on from an extreme, lateral angle (1); absent (2). Coates et al. (2017).

116 Ascending basisphenoid pillar pierced by common internal carotid: absent (0); present (1). Miles (1973b); Brazeau (2009); Friedman & Brazeau (2010); Davis et al. (2012); Zhu et al. (2013).

117 Spiracular groove on basicranial surface: absent (0); present (1). Davis et al. (2012); Zhu et al. (2013).

118 Spiracular groove on lateral or transverse wall of jugular canal: absent (0); present (1). Davis et al. (2012); Zhu et al. (2013).

119 Spiracular groove open (0); enclosed by spiracular bar or canal (1). Lu et al. (2016), Coates et al. (2018).

120 Orbit larger than otic capsule: absent (0); present (1). Lund & Grogan (1997); Coates et al. (2017).121 Postorbital process and arcade: absent (0); present (1). Pradel et al. (2011); see also Maisey (2007)

and Coates et al. (2017). 122 Postorbital process and arcade short and deep - width not more than maximum braincase width

(excluding arcade) (0); process and arcade wide - width exceeds maximum width of braincase,

and anteroposteriorly narrow (1); process and arcade massive (2); arcade forms postorbital

pillar (3). Coates et al. (2017). 123 Postorbital process downturned, with anhedral angle relative to basicranium: absent (0); pres-

ent (1). Present in hybodontids, Acronemus (Maisey 2011) and Tristychius (Dick 1978; Coates & Tietjen 2018).

124 Jugular canal diameter small (0); large (1); canal absent (2). Pradel et al. (2011); Coates et al. (2018).

125 Canal, likely for trigeminal nerve (V) mandibular ramus, passes through the postorbital process

from proximal dorsal entry to distal and ventral exit: absent (0); present (1). (Coates et al., 2017)126 Postorbital process expanded anteroposteriorly: absent (0); present (1). (Coates et al. 2018).127 Postorbital process articulates with palatoquadrate: absent (0); present (1). Schaeffer (1981);

Coates & Sequeira (1998); Maisey (2001a); Pradel et al. (2011); Davis et al. (2012); Zhu et al. (2013). 128 Trigemino-facial recess: absent (0); present (1). Goodrich (1930); Gardiner (1984 and references

therein); Pradel (2010); Pradel et al. (2011); Davis et al. (2012). 129 Jugular canal long, extends throughout most of otic capsule wall posterior to the postorbital

process (0); short and/ or groove present on exterior of otic wall (1); absent, path of jugular re-

moved from otic wall (2). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Giles et al. (2015c); Coates et al. (2017).

130 C-bout notch separates postorbital process from supraotic shelf: absent (0); present (1). Charac-teristic feature of Tristychius, present in Acronemus (Maisey 2011).

131 Postorbital fossa: absent (0); present (1). Zhu et al. (2013).132 Hyoid ramus of facial nerve (N. VII) exits through posterior jugular opening: absent (0); pres-

ent (1). Friedman (2007); Brazeau (2009); Friedman & Brazeau (2010); Davis et al. (2012); Zhu et al. (2013).

133 Periotic process: absent (0); present (1). Maisey (2007); Coates et al. (2017).134 Articulation facet for hyomandibula: single-headed (0), double-headed (1). Zhu et al. (2009,

2013).135 Relative position of jugular groove and hyomandibular articulation: hyomandibula dorsal or

same level (i.e. on bridge) (0); jugular vein passing dorsal or lateral to hyomandibula (1). Brazeau & de Winter (2015).

136 Transverse otic process: absent (0); present (1). Lu et al. (2016); Giles et al. (2016) 137 Craniospinal process: absent (0); present (1). Giles et al. (2015); Lu et al. (2016). 138 Lateral otic process: absent (0); present (1). Schaeffer (1981); Coates & Sequeira (1998); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013). 139 Hyomandibula articulates with neurocranium beneath otic shelf: absent (0); present (1).

140 Sub-otic occipital fossa: absent (0); present (1). Coates et al. (2017, 2018).

158

Chapter IV: Functional Morphology of Symmoriid Jaws

141 Postotic process: absent (0); present (1). Pradel et al. (2011); Coates et al. (2017).142 Otic capsule extends posterolaterally relative to occipital arch: absent (0); present (1). Maisey

(1985).143 Otic capsules: widely separated (0); approaching dorsal midline (1). Coates et al. (2017).144 Otic capsules project anteriorly between postorbital processes: absent (0); present (1). Coates et

al. (2018).145 Endocranial roof anterior to otic capsules dome-like, smoothly convex dorsally and anteriorly:

absent (0); present (1). Coates et al. (2017).146 Roof of skeletal cavity for cerebellum and mesencephalon signifi cantly higher than dorsal-most

level of semicircular canals: absent (0); present (1). Coates et al. (2017).147 Roof of the endocranial space for telencephalon and olfactory tracts offset ventrally relative to

level of mesencephalon: absent (0); present (1). Coates et al. (2017).148 Labyrinth cavity separated from the main neurocranial cavity by a cartilaginous or ossifi ed

capsular wall (0); skeletal medial capsular wall absent (1). Pradel et al. (2011); Davis et al. (2012); Zhu et al. (2013).

149 Double octaval nerve foramena in chondrifi ed mesial wall of otic capsule: absent (0); present

(1). Coates et al. (2018). 150 External (horizontal) semicircular canal joins the vestibular region dorsal to posterior ampulla

(0); joins level with posterior ampulla (1). Davis et al. (2012); Zhu et al. (2013).151 Angle of external semicircular canal: in lateral view, straight line projected through canal in-

tersects anterior ampulla, external ampullae, and base of foramen magnum: absent (0); present

(1). Coates et al. (2017).152 Left and right external semicircular canals approach or meet the posterodorsal midine of the

hindbrain roof: absent (0); present (1). Coates et al. (2017).153 Preampullary portion of posterior semicircular canal absent (0); present (1). Coates et al. (2017). 154 Crus commune connecting anterior and posterior semicircular canals present (0); absent (1).

Coates et al. (2017). 155 Sinus superior: absent or indistinguishable from union of anterior and posterior canals with

saccular chamber (0); present, elongate and nearly vertical (1). Davis et al. (2012); Zhu et al. (2013).

156 Lateral cranial canal: absent (0); present (1). Zhu et al. (2009, 2013); Lu et al. (2016). 157 Endolymphatic ducts: posteriodorsally angled tubes (0); tubes oriented vertically through endo-

lymphatic fossa/posterior dorsal fontanelle (1). Schaeffer (1981); Coates & Sequeira (1998, 2001); Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

158 Posterior dorsal fontanelle connected to persistent otico-occipital fi ssure (0); posterior tectum

separates fontanelle from fi ssure (1). Schaeffer (1981); Coates & Sequeira (1998); Pradel et al. (2011).

159 Subcircular endolymphatic foramen: absent (0); present (1). Pradel et al. (2015), Coates et al. 2017.

160 External opening for endolymphatic ducts anterior to crus commune: absent (0); present (1). Coates et al. (2017).

161 Supraotic shelf broad: absent (0); present (1). Coates et al. (2017).162 Dorsal otic ridge: absent (0); present (1). Coates & Sequeira (1998, 2001); Maisey (2001); Davis

(2002); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).163 Dorsal otic ridge forms a crest posteriorly: absent (0); present (1). Coates & Sequeira (1998,

2001); Pradel et al. (2011).164 Endolymphatic fossa: absent (0); present (1). Pradel et al. (2011). 165 Endolymphatic fossa elongate (slot-shaped), dividing dorsal otic ridge along midline: absent (0);

present (1). Coates et al. (2017). 166 Perilymphatic fenestra within the endolymphatic fossa: absent (0); present (1). Pradel et al.

(2011); Coates et al. (2017).167 Ventral cranial fi ssure: absent (0); present (1). Janvier (1996); Coates & Sequeira (2001); Maisey

(2001); Davis (2002); Brazeau (2009); Pradel et al. (2011); Davis et al. (2012); Zhu et al. (2013).168 Endoskeletal intracranial joint: absent (0); present (1). Janvier (1996); Davis et al. (2012); Zhu et

al. (2013).169 Metotic (otic-occipital) fi ssure: absent (0); present (1). Schaeffer (1981); Janvier (1996); Coates

159

Chapter IV: Functional Morphology of Symmoriid Jaws

& Sequeira (1998); Maisey (2001); Davis (2002); Brazeau (2009); Pradel et al. (2011); Davis et al. (2012); Zhu et al. (2013).

170 Vestibular fontanelle: absent (0); present (1). Brazeau (2009); Friedman & Brazeau (2010). Davis et al. (2012); Zhu et al. (2013).

171 Hypotic lamina: absent (0); present (1). Schaeffer (1981); Maisey (1984, 2001); Brazeau (2009); Pradel et al. (2011, 2013); Davis et al. (2012); Zhu et al. (2013); Coates et al. (2017).

172 Glossopharyngeal nerve path: directed laterally, across fl oor of the saccular chamber and exits

via foramen in side wall of the otic capsule (0); directed posteriorly, and exits through metotic

fi ssure or foramen in posteroventral wall of otic capsule (1); exits laterally through a canal con-

tained ventrally (fl oored) by the hypotic lamina (2); exits through a foramen anterior to the pos-

terior ampulla (3). Coates et al. (2017), adapted from Schaeffer (1981); Coates & Sequeira (1998, 2001); Brazeau (2009): Davis et al. (2012); Zhu et al. (2013); Pradel et al. (2011, 2013).

173 Glossopharyngeal and vagus nerves share common exit from neurocranium: absent (0); present

(1). Coates et al. (2017).174 Basicranial morphology: platybasic (0); tropibasic (1). Brazeau (2009); Pradel et al. (2011); Davis

et al. (2012); Zhu et al. (2013). 175 Channel for dorsal aorta and/or lateral dorsal aortae passes through basicranium (0): exter-

nal to basicranium (1). Schaeffer (1981); Coates & Sequeira (1998); Brazeau (2009); Pradel et al. (2011); Brazeau & Friedman (2014); Coates et al. (2017).

176 Dorsal aorta divides into lateral dorsal aortae posterior to occipital level (0); anterior to level of

the occiput (1). Pradel et al. (2011); Giles et al. (2015); Coates et al. (2017).177 Ventral portion of occipital arch wedged between rear of otic capsules: absent (0); present (1).

Schaeffer (1981); Coates & Sequeira (1998); Maisey (2001a); Brazeau (2009); Pradel et al. (2011); Davis et al. (2012); Coates et al. (2017).

178 Dorsal portion of occipital arch wedged between otic capsules: absent (0); present (1). Schaeffer (1981); Coates & Sequeira (1998); Maisey (2001a); Brazeau (2009); Pradel et al. (2011); Davis et al. (2012); Coates et al. (2017).

179 Occipital crest anteroposteriorly elongate, and extends from the roof of the posterior tectum:

absent (0); present (1). Coates et al. (2018).

Axial and appendicular skeleton180 Calcifi ed vertebral centra: absent (0); present (1). Maisey (1985); Coates et al. (2017).181 Chordacentra: absent (0); present (1). Stahl (1999); Coates and Sequeira (2001); Coates et al.

(2017). 182 Chordacentra polyspondylous and consist of narrow closely packed rings: absent (0); present

(1). Derived from Patterson (1965); Coates et al. (2017).183 Synarcual: absent (0); present (1). Stahl (1999); Brazeau (2009); Davis et al. (2012); Zhu et al.

(2013); Coates et al. (2017).184 Macromeric dermal pectoral girdle (0); micromeric or lacking dermal skeleton entirely (1).

Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).185 Macromeric dermal pectoral girdle composition: ventral and dorsal components (0); ventral

components only (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).186 Macromeric pectoral dermal skeleton forms complete ring around the trunk: present (0); ab-

sent (1). Goujet & Young (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).187 Median dorsal plate: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).188 Scapular process (dorsal) of shoulder endoskeleton: absent (0); present (1). Coates & Sequeira

(2001a); Zhu & Schultze (2001); Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).

189 Ventral margin of separate scapular ossifi cation: horizontal (0); deeply angled (1). Hanke & Wilson (2004); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).

190 Cross sectional shape of scapular process: fl attened or strongly ovate (0); subcircular (1). Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).

191 Flange on trailing edge of scapulocoracoid: absent (0); present (1). Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).

192 Scapular process with posterodorsal process: absent (0); present (1). Coates & Sequeira (2001a); Davis et al. (2012); Zhu et al. (2013).

160

Chapter IV: Functional Morphology of Symmoriid Jaws

193 Mineralisation of internal surface of scapular process: mineralised all around (0); un-min-

eralised on internal face forming a hemicylindrical cross-section. Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Burrow et al. (2016).

194 Coracoid process: absent (0); present (1). Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).195 Procoracoid mineralisation: absent (0); present (1). Davis (2002); Hanke & Wilson (2004): Brazeau

(2009).196 Fin base articulation on scapulocoracoid: stenobasal, deeper than wide (0); eurybasal, wider

than deep (1). Lu et al. (2016).197 Pectoral fi n articulation monobasal (0); dibasal (1); three or more basals (2).

198 Metapterygium pectinate subtriangular plate or bar supporting numerous (six or more) radials

along distal edge: absent (0); present (1). Coates et al. (2018).199 Metapterygial whip: absent (0); present (1). Coates et al. (2017).200 Biserial pectoral fi n endoskeleton: absent (0); present (1). Lu et al. (2016).201 Propterygium perforated: absent (0); present (1). Rosen et al. (1981); Patterson (1982); Davis et

al. (2012); Zhu et al. (2013).202 Pelvic girdle with fused puboischiadic bar: absent (0); present (1). Maisey (1984); Coates & Se-

queira (2001a); Coates et al. (2017).203 Mixipterygial/ mixopterygial claspers: absent (0), present (1). Coates & Sequeira (2001a, b);

Brazeau & Friedman (2014). 204 Pre-pelvic clasper or tenaculum: absent (0); present (1). After Patterson (1965); Coates et al.

(2017).205 Number of dorsal fi ns, if present: one (0); two (1); one, extending from pectoral to anal fi n level

(2). Coates & Sequeira (2001a); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013).206 Brush complex of bilaterally distributed calcifi ed tubes fl anking or embedded in calcifi ed carti-

lage core: absent (0); present (1). Coates et al. (2017, 2018)207 Posterior or pelvic-level dorsal fi n with calcifi ed base plate: absent (0); present (1). Coates &

Sequeira (2001a, b). 208 Posterior dorsal fi n with delta-shaped cartilage: absent (0); present (1). Coates & Sequeira (2001a,

b). 209 Posterior or pelvic-level dorsal fi n shape, base approximately as broad as tall and not broader

than other median fi ns (0); base much longer than fi n height, substantially longer than other

median fi ns (1). Brazeau & deWinter (2015); Lu et al. (2017). 210 Anal fi n: absent (0); present (1). Coates & Sequeira (2001); Brazeau (2009); Davis et al. (2012);

Zhu et al. (2013).211 Anal fi n base narrow, posteriormost proximal segments radials broad: absent (0); present (1).

Heidtke (1999). 212 Caudal radials restricted to axial lobe (0); extend beyond level of body wall and deep into hypo-

chordal lobe (1). Davis et al. (2012); Zhu et al. (2013). 213 Caudal neural and/or supraneural spines or radials short (0); long, expanded, and supporting

high aspect-ratio (lunate) tail with notochord extending to posterodorsal extremity (1); noto-

chord terminates pre-caudal extremity, neural and heamal radial lengths near symmetrical and

support epichordal and hypochordal lobes respectively (2). Coates & Sequeira (2001a, b).

Spines: fi ns, cranial and elsewhere214 Dorsal fi n spine or spines: absent (0); present (1). Zhu et al. (2001); Zhu & Yu (2002); Friedman

(2007); Brazeau (2009); Davis et al. (2012); Zhu et al. (2013); Lu et al. (2016). 215 Dorsal fi n spine at anterior (pectoral level) location only: absent (0); present (1). Coates & Sequei-

ra (2001a); Ginter et al. (2010). 216 Dorsal fi n spine cross section: horseshoe shaped (0); fl at sided, with rectangular profi le (1); sub-

circular (2). Hampe (2003); Brazeau & de Winter (2015).217 Anterior dorsal fi n spine leading edge concave in lateral view: absent (0); present (1). Lund

(1985, 1986).218 Anal fi n spine: absent (0); present (1). Maisey (1986); Davis (2002); Brazeau (2009).219 Pectoral fi n spines: absent (0); present (1). Davis (2002); Brazeau (2009); Davis et al. (2012); Zhu

et al. (2013).220 Pectoral fi n spine with denticles along posterior surface: absent (0); present (1). Burrow et al.

161

Chapter IV: Functional Morphology of Symmoriid Jaws

(2016).221 Prepectoral fi n spines: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau

(2009); Davis et al. (2012); Zhu et al. (2013). Present in Doliodus (Maisey et al. 2017).222 Admedian pectoral spines absent (0); present (1). Burrow et al. (2016); see also description of

Doliodus pectoral girdle (Maisey et al. 2017).223 Median fi n spine insertion: shallow, not greatly deeper than dermal bones/ scales (0); deep (1).

Davis (2002); Hanke & Wilson (2004); Brazeau (2009). Davis et al. (2012); Zhu et al. (2013).224 Intermediate (pre-pelvic) fi n spines: absent (0); present (1). Davis (2002); Hanke & Wilson (2004);

Brazeau (2009); Davis et al. (2012); Zhu et al. (2013). 225 Fin spines with ridges: absent (0); present (1). Davis (2002); Brazeau (2009); Davis et al. (2012);

Zhu et al. (2013).226 Fin spines with nodes: absent (0); present (1). Davis (2002); Hanke & Wilson (2004); Brazeau

(2009). Davis et al. (2012); Zhu et al. (2013).227 Fin spines (dorsal) with rows of large denticles: absent (0); on posterior surface (1); on lateral

surface (2). Maisey (1989b); Davis et al. (2012); Zhu et al. (2013); Brazeau & Friedman (2014).228 Cephalic spines: absent (0); present (1). Maisey (1989); Coates et al. (2017)

4. References

Arratia, G. & Cloutier, R. in Devonian Fishes and Plants of Migua-sha, Quebec, Canada (eds. Schultze, H.-P. & Cloutier, R.) 165-197 (Verlag Dr. Friedrich Pfeil, Munich, 1996).

Bendix-Almgreen, S. E. The paired fi ns and shoulder girdle in Cladoselache, their morphology and phyletic signifi cance. Colloques Internationaux du Centre National de la Recherche Scientifi que 218, 111-123 (1975).

Bernacsek, G.M., & Dineley, D.L. New acanthodians from the Delo-rme Formation (Lower Devonian) of N.W.T., Canada. Paleonto-graphica Abt.A 158, 1-25 (1977).

Brazeau, M. D. The braincase and jaws of a Devonian ‘acanthodian’ and modern gnathostome origins. Nature 457, 305-308 (2009).

Brazeau, M. D. A revision of the anatomy of the early Devonian jawed vertebrate Ptomacanthus anglicus Miles. Palaeontology 55, 355-367 (2012).

Brazeau, M. D. & Friedman, M. The characters of Palaeozoic jawed vertebrates. Zoological Journal of the Linnean Society, 170, 779-821 (2014).

Brazeau, M. D. & de Winter, V. The hyoid arch and braincase anato-my of Acanthodes support chondrichthyan affi nity of ‘acantho-dians’. Proc. R. Soc. B 282: 20152210 (2015).

Brazeau, M. D., Friedman, M., Jerve, A., & Atwood, R. C. A three-dimensional placoderm (stem-group gnathostome) pha-ryngeal skeleton and its implications for primitive gnathostome pharyngeal architecture. Journal of Morphology. DOI: 10.1002/jmor.20706 (2017).

Burrow, C. J. A partial articulated acanthodian from the Silurian of New Brunswick, Canada. Canadian Journal of Earth Sciences 48(9), 1329–1341. doi:10.1139/e11-023 (2011).

Burrow, C. J., den Blaauwen, J., Newman, M. & Davidson, R. The diplacanthid fi shes (Acanthodii, Diplacanthiformes, Diplacan-thidae) from the Middle Devonian of Scotland. Palaeontologica Electronica 19, 1-83 (2016).

Burrow, C. J. & Rudkin, D. Oldest near-complete acanthodian: the fi rst vertebrate from the Silurian Bertie formation Konser-vat-Lagerstätte, Ontario. PLoS ONE 9(8), DOI:10.1371/journal.pone.0104171 (2014).

Burrow, C. J., Trinajstic, K. & Long, J. First acanthodian from the Upper Devonian (Frasnian) Gogo Formation, Western Austra-lia. Historical Biology 24, DOI:10.1080/08912963.2012.660150 (2012).

Burrow, C. J. & Turner, S. Scale structure of the putative chondrich-thyan Gladbachus adentatus Heidtke & Krätschmer, 2001 from the Middle Devonian Rheinisches Schiefergebirge, Germany. Historical Biology 25, 385-390 (2013).

Carr, R. K., Johanson, Z. & Ritchie, A. The phyllolepid placoderm Cowralepis mclachlani: insights into the evolution of feed-ing mechanisms in jawed vertebrates. J. Morph. 270, 775-804 (2009).

Chang, M. M. The braincase of Youngolepis, a Lower Devonian

crossopterygian from Yunnan, south-western China. Doctor-al dissertation, Department of Geology, Stockholm University (1982).

Chang, M. M. Head exoskeleton and shoulder girdle of Youngole-pis. In Early vertebrates and related problems of evolutionary biology, M. M. Chang, Y. H. Liu & G. R. Zhang, eds. (Beijing: Science Press), pp. 355-378 (1991).

Chang, M. M. Synapomorphies and scenarios - more characters of Youngolepis betraying its affi nity to the Dipnoi. In Recent Ad-vances in the Origin and Early Radiation of Vertebrates, G. Ar-ratia, M. V. H. Wilson & R. Cloutier, eds. (München: Verlag Dr. Friedrich Pfeil), pp. 665-686 (2004).

Chang, M.-M. & Yu, X.-B. A new crossopterygian, Youngolepis praecursor, gen. et sp. nov., from Lower Devonian of E. Yun-nan, China. Sci. Sin. 24, 89-97 (1981).

Choo, B. Revision of the actinopterygian genus Mimipiscis (= Mimia) from the Upper Devonian Gogo Formation of West-ern Australia and the interrelationships of early Actinopterygii. Earth and Environmental Science Transactions of the Royal So-ciety of Edinburgh, 102, 77-104 (2011)

Coates, M. I. Endocranial preservation of a Carboniferous actinopte-rygian from Lancashire, UK, and the interrelationships of prim-itive actinopterygians. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 354 (1382), 435-462 (1999).

Coates, M.I., Finarelli, J.A., Sansom, I.J., Andreev, P.S., Criswell, K.E., Tietjen, K., Rivers, M.L. & La Riviere, P.J. An early chondrichthyan and the evolutionary assembly of a shark body plan. Proceedings of the Royal Society B 285: 20172418. (2018) http://dx.doi.org/10.1098/rspb.2017.2418

Coates, M.I., & Gess, R.W. A new reconstruction of Onychoselache traquairi, comments on early chondrichthyan pectoral girdles and hybodontiform phylogeny. Palaeontology, 50(6), 1421-1446 (2007).

Coates, M. I., Gess, R. W., Finarelli, J. A., Criswell, K. E. & Tietjen, K. A symmoriiform chondrichthyan braincase and the origin of chimaeroid fi shes. Nature 541, 209-211 (2017).

Coates, M. I., Sansom, I. J. & Smith, M. M. Spines and tissues of ancient sharks. Nature 396, 729-730 (1998).

Coates, M. I. & Sequeira, S. E. K. The braincase of a primitive shark. Trans. R. Soc. Edinb. (Earth Sci.) 89, 63-85 (1998).

Coates, M. I. & Sequeira, S. E. K. A new stethacanthid chondrich-thyan from the Lower Carboniferous of Bearsden, Scotland. J. Vertebr. Paleontol. 21, 754-766 (2001a).

Coates, M. I. & Sequeira, S. E. K. in Major Events in Early Verte-brate Evolution (ed. Ahlberg, P. E.) 241-262 (Taylor and Fran-cis, 2001b).

Coates, M. I. & Tietjen, K. The neurocranium of the Lower Car-boniferous shark Tristychius arcuatus (Agassiz, 1837). Earth and Environmental Science Transactions of the Royal Society of Edinburgh (2018).

Cole, F. J. On the cranial nerves of Chimaera monstrosa (Linn.); with a discussion of the lateral line system and of the morphology of

162

Chapter IV: Functional Morphology of Symmoriid Jaws

the chorda tympani. Trans. R. Soc. Edinb. 38, 631-680 (1896).Davis, S. P. Comparative anatomy and relationships of the acanthodi-

an fi shes. Unpublished PhD thesis, Unv. London, 1-318. (2002).Davis, S. P., Finarelli, J. A., & Coates, M. I. Acanthodes and shark-

like conditions in the last common ancestor of modern gnatho-stomes. Nature 486, 247-250 (2012).

Dean, M. N. & Summers, A. P. Cartilage in the skeleton of cartilagi-nous fi shes. Zoology 109,164-168 (2006).

Dean, M. N., Mull, C. G., Gorb, S. N. & Summers, A. P. Ontogeny of the tessellated skeleton: insight form the skeletal growth of the round stingray Urobatis halleri. J. Anat. DOI:10.1111/j.1469-7580.2009.01116x (2009).

Denison, R. in Handbook of Paleoichthyology Vol. 5 (ed. Schultze, H.-P.) (Gustav Fischer Verlag, Stuttgart, 1979).

Dick, J. R. F. On the Carboniferous shark Tristychius arcuatus Agas-siz from Scotland. Trans. R. Soc. Edinb. 70, 63-109 (1978).

Dick, J. R. F. Diplodoselache woodi gen. et sp. nov., an early Car-boniferous shark from the Midland Valley of Scotland. Trans. R. Soc. Edinb. 72, 99-113 (1981).

Dick, J. R. F. & Maisey, J. G. The Scottish Lower Carboniferous shark Onychoselache traquairi. Palaeontology 23, 363-374 (1980).

Didier, D. A. Phylogenetic systematics of extant chimaeroid fi sh-es (Holocephali, Chimaeroidei). Am. Mus. Novit. 3119, 1-86 (1995).

Didier, D. A., Kemper, J. M. & Ebert, D. A. in Biology of Sharks and Their Relatives (eds Carrier, J. C., Musick, J. & Heithaus, M. R.) 97-122 (CRC Press, 2012).

Didier, D. A., Stahl, B. J. & Zangerl R. Development and growth of compound tooth plates in Callorhinchus milii (Chondrichthyes, Holocephali). Journal of Morphology 222, 73-89 (1994).

Donoghue, P.C.J., & Aldridge, R. J. in Major events in early verte-brate evolution: palaeontology, phylogeny, genetics and devel-opment. (ed Ahlberg, P. E.) 85–105 (Taylor & Francis, 2001).

Donoghue, P. C. J., Forey, P. L., & Aldridge, R. J. Conodont affi nity and chordate phylogeny. Biol. Rev.75, 191-251 (2000).

Dupret, V., Sanchez, S., Goujet, D., Tafforeau, P. & Ahlberg, P. E. A primitive placoderm sheds light on the origin of the jawed vertebrate face. Nature 507, 500-503 (2014).

Eastman, C. R. Tamiobatis vetustus: a new form of fossil skate. American Journal of Science

4(4), 85-90 (1897A). Finarelli, J. A. & Coates, M. I. First tooth-set outside the jaws in a

vertebrate. Proceedings of the Royal Society of London Series B-Biological Sciences 279, 775-779 (2012).

Finarelli, J. A. & Coates, M. I. Chondrenchelys problematica (Tra-quair, 1888) redescribed: a Lower Carboniferous, eel-like ho-locephalan from Scotland. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 105, 1-25 (2014).

Forey, P. L. Latimeria: a paradoxical fi sh. Proc. R. Soc. London, Ser. B 208, 369-384 (1980).

Friedman, M. Styloichthys as the oldest coelacanth: implications for early osteichthyan interrelationships. J. Syst. Palaeontol. 5, 289-343 (2007).

Friedman, M. & Brazeau, M. A reappraisal of the origin and basal radiation of the Osteichthyes. J. Vertebr. Paleontol. 30, 36-56 (2010).

Gans, C. & Parsons, T. S. A Photographic Atlas of Shark Anatomy (Academic Press, New York, 1964).

Gagnier, P. Y. in Devonian Fishes and Plants of Miguasha, Quebec, Canada. (eds Schultze, H. P. & Cloutier, R.) 149-163 (Freidrich Pfeil, 1996).

Gagnier, P. Y., Hanke, G. F. & Wilson, M. V. H. Tetanopsyrus lin-doei gen. et sp. nov., an Early Devonian acanthodian from the Northwest Territories, Canada. Acta Geologica Polonica 49, 81-96 (1999).

Gagnier, P. Y. & Wilson, M. V. H. New evidences on jaw bones and jaw articulations in acanthodians. Geobios 19 (1995).

Gagnier, P. Y. & Wilson, M. V. H. Early Devonian acanthodians from northern Canada. Palaeontology 39, 241-258 (1996a).

Gagnier P. Y. & Wilson M. V. H. An unusual acanthodian from Northern Canada: revision of Brochoadmones milesi. Modern Geology 20, 235-251 (1996b).

Gardiner, B. G. The relationships of the palaeoniscoid fi shes, a re-view based on new specimens of Mimia and Moythomasia from the Upper Devonian of Western Australia. Bull. Br. Mus. Nat.

Hist. (Geol.) 37, 173-428 (1984).Giles, S., Coates, M., Garwood, R. J., Brazeau, M. D., Atwood, R.,

Johanson, Z. & Friedman, M. Enodskeletal structure in Cher-olepis (Osteichthyes, Actinopterygii), an early ray-fi nned fi sh. Palaeontology 2015, DOI:10.1111/pala. 12182 (2015a).

Giles, S., Darras, L., Clément, G., Blieck, A. & Friedman, M. An ex-ceptionally preserved Late Devonian actinopterygian provides a new model for primitive cranial anatomy in ray-fi nned fi shes. Proc. R. Soc. B 282: 20151485 (2015b).

Giles, S., Friedman, M. Virtual reconstruction of endocast anatomy in early ray-fi nned fi shes (Osteichthyes, Actinopterygii). Jour-nal of Paleontology, 88(4), 636-651 (2014).

Giles, S., Friedman, M. & Brazeau, M. D. Osteichthyan-like cranial conditions in an Early Devonian stem gnathostome. Nature 520,

82-85 (2015c).Ginter, M. Late Famennian shark teeth from the Holy Cross Mts,

Central Poland. Acta Geologica Polonica 40, 69-81 (1990). Ginter, M. Late Famennian pelagic shark assemblages. Acta Geolog-

ica Polonica 50(2), 369-386 (2000).Ginter, M., Hairapetian, V. & Klug, C. Famennian chondrichthyans

from the shelves of North Gondwana. Acta Geologica Polonica 52(2), 169-215 (2002).

Ginter, M., Hampe, O. & Duffi n, C. J. Chondrichthyes: Paleozoic Elasmobranchii: teeth, in: Schultze, H. (Ed.), Handbook of Pa-leoichthyology, 3D, 168 p. (2010).

Ginter, M. & Ivanov, A. Devonian phoebodont shark teeth. Acta Pa-laeontologica

Polonica 37(1), 55-75 (1992).Ginter, M. & Ivanov, A. Middle/Late Devonian Phoebodont-based

ichthyolith zonation. [Zonation ichthyologique du Dévonien moyen/supérieur fondée sur les Phoebodontes]. Geobios 19, 351-355 (1995).

Ginter, M. & Sun, Y. Chondrichthyan remains from the Lower Car-boniferous of Muhua, southern China. Acta Palaeontologica Polonica 52(4), 705-727 (2007).

Ginter, M. & Turner, S. The middle Paleozoic Selachian genus Thri-nacodus. Journal of Vertebrate Paleontology 30(6), 1666-1672, (2010), doi:10.1080/02724634.2010.520785.

Goodrich E. S. Studies on the structure and development of verte-brates (Univ. Chicago Press, 1930).

Goujet D, & Young G. C. in Recent Advances in the Origin and Early Radiation of Vertebrates, (eds Arratia, G., Wilson, M. V. H. & Cloutier, R.) 109-26 (Friedrich Pfeil, 2004).

Grogan, E. D. and Lund, R. Debeerius ellefseni (Fam. Nov., Gen. Nov., Sped. Nov.) an Autodiastylic Chondrichthyan From the Mississippian Bear Gulch Limestone of Montana (USA), the Relationships of the Chondrichthyes, and Comments on Gna-thostome Evolution. J. Morphol. 243, 219-245 (2000).

Grogan, E.D. & Lund, R. A basal elasmobranch, Thrinacoselache gracia n. gen & sp., (Thrinacodontidae, new family) from the Bear Gulch Limestone, Serpukhovian of Montana, USA. Jour-nal of Vertebrate Paleontology 28(4), 970-988 (2008).

Grogan, E. D., Lund, R. & Greenfest-Allen, E. in Biology of Sharks and Their Relatives (eds Carrier, J. C., Musick, J. A. & Heithaus, M. R.) 3-29 (CRC Press, 2012).

Gross, W. Das Kopfskelett on Cladodus wildungensis Jaekel; 1. Teil. Endocranium und Palatoquadratum. Senckenbergiana 19, 80-107 (1937).

Gross, W. Das Kopfskelett on Cladodus wildungensis Jaekel; 2. Teil. Der Kieferbogen. Anhang: Protractodus vetusus Jaekel. Senck-enbergiana 20, 123-145 (1938).

Hampe, O. Revision of the Xenacanthida (Chondrichthyes: Elasmo-branchii) from the Carboniferous of the British Isles. Trans. R. Soc. Edinb. (Earth Sci.) 93, 191-237 (2003).

Hanke G. F. Promesacanthus eppleri n. gen., n. sp., a mesacanthid (Acanthodii, Acanthodiformes) from the Lower Devonian of northern Canada. Geodiversitas 30, 287-302 (2008).

Hanke, G. F. & Davis, S. P. Redescription of the acanthodian Gladio-branchus probaton Bernacsek & Dineley, 1977, and comments on diplacanthid relationships. Geodiversitas 30, 303-330 (2008).

Hanke, G. F. & Davis, S. P. A re-examination of Lupopsyrus pygmae-us Bernacsek & Dineley, 1977 (Pisces, Acanthodii). Geodiversi-tas 34, 469-487 (2012).

Hanke, G. F., Davis, S. P. & Wilson, M. V. H. A new species of the acanthodian genus Tetanopsyrus from Northern Canada, with comments on related taxa. J. Vert. Paleontol. 21, 740-753 (2001).

163

Chapter IV: Functional Morphology of Symmoriid Jaws

Hanke, G. F., & Wilson, M. V. H. in Recent Advances in the Origin and Early Radiation of Vertebrates. (eds Arratia, G., Wilson, M. V. H., & Cloutier, R.) 189–216 (Freidrich Pfeil, 2004).

Hanke, G. F. & Wilson, M. V. H. Anatomy of the Early Devonian Acanthodian Brochoadmones milesi based on nearly complete body fossils, with comments on the evolution and development of paired fi ns. J. Vert. Paleontol. 26, 526-537 (2006).

Hanke, G. F., & Wilson, M. V. H. in Morphology, Phylogeny and Paleobiogeography of Fossil Fishes. (eds Elliot, D.K., Maisey, J.G., Yu, X. & Miao, D.) 159-182 (Freidrich Pfeil, 2010).

Harris, J. E. The dorsal fi n spine of Cladoselache. Scientifi c Pub-lications of the Cleveland Museum of Natural History 8, 1-6 (1938a).

Harris, J. E. The neurocranium and jaws of Cladoselache. Scientif-ic Publications of the Cleveland Museum of Natural History 8, 7-12 (1938b).

Heidtke, U. H. J. Der Xenacanthide Orthacanthus senckenbergianus aus dem pfälzischen Rotliegenden (Unter-Perm). Pollichia 70, 65-86 (1982).

Heidtke, U. Studien über Acanthodes. 4. Acanthodes boyi n. sp., die dritte Art der Acanthodier (Acanthodii: Pisces) aus dem Rotlie-gend (Unterperm) des Saar-Nahe-Beckens (S-W-Deutschland. Paläont. Z. 67, 331-341 (1993).

Heidtke, U. H. J. Orthacanthus (Lebachacanthus) senckenbergianus Fritsch 1889 (Xenacanthida: Chondrichthyes): revision, organi-sation und phylogenie. Freiberger Forschungsheft 481, 63-106 (1999).

Heidtke, U. H. J. Gladbachus adentatus, die Geschichte des weltweit ältesten Hais – untersucht und beschriebenaus dem AK Geowis-senschaften. Pollichia Kurrier 25, 24-26 (2009).

Heidtke, U. H. J. Neue Erkenntnisse über Acanthodes bronni Agassiz 1833. Mitt. Pollichia 95, 1-14 (2011a).

Heidtke, U. H. J. Revision der unterpermischen Acanthodier (Acan-thodii: Pisces) des südwestdeutschen Saar-Nahe-Beckens. Mitt. Pollichia 95, 15-41 (2011b).

Heidtke, U. H. J. & Krätschmer K. Gladbachus adentatus nov. gen. et sp., ein primitiver Hai aus dem Oberen Givetium (Oberes Mit-teldevon) der Bergisch Gladbach – Paffrath-Mulde (Rheinisches Schiefergebirge). Mainzer geowiss. Mitt. 30, 105-122 (2001).

Heidtke, U. H. J., Schwind, C. & Krätschmer K. Über die Organisa-tion des Skelettes und die verwandschaftlichen Beziehungen der Gattung Triodus Jordan 1849 (Elasmobranchii: Xenacanthida). Mainzer geowiss. Mitt. 32, 9-54 (2004).

Hotton, N. Jaws and teeth of American xenacanth sharks. Journal of Paleontology 26, 489-500 (1952).

Howard, L. E., Holmes, W. M., Ferrando, S., Maclaine, J. S., Kelsh, R. N., Ramsey, A., Abel R. L. & Cox P. L. J. Functional nasal morphology of chimaeroid fi shes. Journal of Morphology 274: 987-1009 (2013).

Janvier, P. Early Vertebrates (Oxford Univ. Press, 1996).Janvier, P. & Maisey, J. G. (2010) in Morphology, Phylogeny and

Paleobiogeography of Fossil Fishes. (eds Elliot, D.K., Maisey, J.G., Yu, X. & Miao, D.) 431-459 (Freidrich Pfeil, 2010).

Jarvik, E. in Problems in Vertebrate Evolution. (eds Andrews, S. M., Miles, R. S., Walker & A. D.) 199-225 (Linnean Symposium Series, London, 1977).

Jarvik, E. Basic Structure and Evolution of Vertebrates (Academic, 1980).

Kesteven, H. L. The anatomy of the head of Callorhynchus antarcti-cus. Journal of Anatomy 67, 443-474 (1937).

Lane, J. A. Morphology of the braincase in the Cretaceous hybodont shark Tribodus linnae (Chondrichthyes: Elasmobranchii), based on CT scanning. Amer. Mus. Novitates 2758, 1-70 (2010).

Lane, J. A. & Maisey, J. G. Pectoral anatomy of Tribodus limae (Elasmobranchii: Hybodontiformes) from the Lower Cretaceous of Northeastern Brazil. Journal of Vertebrate Paleontology 29, 25-38 (2009).

Lane, J. A. & Maisey, J. G. The visceral skeleton and jaw suspension in the durophagous hybodontid shark Tribodus limae from the Lower Cretaceous of Brazil. Journal of Paleontology 86, 886-905 (2012).

Long, J. A. A new diplacanthoid acanthodian from the Late Devoni-an of Victoria. Memoirs of the Association of Australasian Pa-laeontologists 1, 51-65 (1983).

Long, J. A., Burrow, C. J., Ginter, M., Maisey, J., Trinajstic, K. M., Coates, M. I., Young, G. C. & Senden, T. J. First shark from the Late Devonian (Frasnian) Gogo Formation, Western Aus-

tralia sheds new light on the development of tessellated calci-fi ed cartilage. PLoS ONE 10: e0126066 DOI:10.1371/journal.pone.0126066 (2015).

Lund, R. Harpagofututor volsellorhinus new genus and species (Chondrichthyes, Chondrenchelyiformes) from the Namurian Bear Gulch Limestone, Chondrenchelys problematica Traquair (Visean), and their sexual dimorphism. Journal of Paleontology 56, 938-958 (1982).

Lund, R.. Stethacanthid elasmobranch remains from the Bear Gulch Limestone (Namurian E2b) of Montana. American Museum No-vitates 2828, 1-24 (1985a).

Lund, R. The morphology of Falcatus falcatus (St. John and Worth-en), a Mississippian stethacanthid chndrichthyan from the Bear Gulch Limestone of Montana. Journal of Vertebrate Paleontol-ogy 5, 1-19 (1985b).

Lund, R. On Damocles serratus nov. gen. et sp., (Elasmobranchii: Cladodontida) from the Upper Mississippian Bear Gulch Lime-stone of Montana. Journal of Vertebrate Paleontology 6, 12-19 (1986).

Lund, R. & Grogan, E. D. Relationships of the Chimaeriformes and the basal radiation of the Chondrichthyes. Reviews in Fish Biol-ogy and Fisheries 7, 65-123 (1997).

Lund, R. & Grogan, E. D. in Recent Advances in the Origin and Ear-ly Radiation of Vertebrates (eds Arratia, G., Wilson, M. V. H. & Cloutier, R.) 171-187 (Friedrich Pfi el, 2004a).

Lund, R. & Grogan, E. D. in Recent Advances in the Origin and Ear-ly Radiation of Vertebrates (eds Arratia, G., Wilson, M. V. H. & Cloutier, R.) 505-531 (Friedrich Pfi el, 2004b).

Maisey, J. G. The anatomy and interrelationships of Mesozoic hy-bodont sharks. Am. Mus. Novit. 2724, 1-48 (1982).

Maisey, J. G. Cranial anatomy of Hybodus basanus Egerton from the Lower Cretaceous of England. Am. Mus. Novit. 2758, 1-64 (1983).

Maisey, J. G. Cranial Morphology of the Fossil Elasmobranch Syn-echodus dubrisiensis. Am. Mus. Novit. 2804, 1-28 (1985).

Maisey, J. G. Visceral skeleton and musculature of a Late Devonian shark. J. Vertebr. Paleontol. 9, 174-190 (1989a).

Maisey, J. G. Hamiltonichthys mapesi g. & sp. nov. (Chondrichthy-es; Elasmobranchii), from the Upper Pennsylvanian of Kansas. American Museum Novitates 2931, 1-42 (1989b).

Maisey, J. G. in Major Events in Early Vertebrate Evolution (ed. Ahl-berg, P. E.) 263-288 (Taylor and Francis, 2001a).

Maisey, J. G. Remarks on the inner ear of elasmobranchs and its in-terpretation from skeletal labyrinth morphology. J. Morph. 250, 236-264. (2001b).

Maisey, J. G. Braincase of the Upper Devonian shark Cladodoides wildungensis (Chondrichthyes, Elasmobranchii), with observa-tions on the braincase in early chondrichthyans. Bull. Am. Mus. Nat. Hist. 288, 1-103 (2005).

Maisey, J. G. The braincase in Paleozoic symmoriiform and cladose-lachian sharks. Bull. Am. Mus. Nat. Hist. 307, 1-122 (2007).

Maisey, J. G. The braincase of the Middle Triassic shark Acronemus tuberculatus (Bassani, 1886). Palaeontology 54, 417-428 (2011).

Maisey, J. G. The diversity of tessellated calcifi cation in modern and extinct chondrichthyans. Revue de Paléobiologie, Geneve 32, 355-371 (2013).

Maisey, J. G. & Anderson, M. E. A primitive chondrichthyan brain-case from the Early Devonian of South Africa. Journal of Verte-brate Paleontology 21, 702-713 (2001).

Maisey, J. G. & de Carvalho, M. R. A new look at old sharks. Nature 385, 779-780 (1997).

Maisey, J. G. & Lane, J. A. Labyrinth morphology and the evolution of low-frequency phonoreception in elasmobranchs. C. R. Pa-levol 9, 289-309. (2010)

Maisey, J. G., Miller, R. & Turner, S. The braincase of the chon-drichthyan Doliodus from the Lower Devonian Campbellton Formation of New Brunswick, Canada. Acta Zoologica 90 (sup-plement 1), 109-122 (2009).

Maisey, J. G., Miller, R., Pradel, A., Denton, J. S. S., Bronson, A. & Janvier, P. Pectoral morphology in Doliodus: bridging the ‘ac-anthodian’-chondrichthyan divide. American Museum Novitates 3875, 1-15. (2017).

Maisey, J. G., Turner, S., Naylor, G. J. P. & Miller, R. F. Dental pat-terning in the earliest sharks: implications for tooth evolution. Journal of Morphology. DOI:10.1002/jmor.20242 (2013)

Marinelli, W. & Strenger, A. Vergleichende Anatomie und Morpholo-

164

Chapter IV: Functional Morphology of Symmoriid Jaws

gie der Wirbeltiere. III. 174-308 (Franz Deuticke, Wien, 1959).Miles, R. S. Articulated acanthodian fi shes from the Old Red Sand-

stone of England, with a review of the structure and evolution of the acanthodian shoulder- girdle. Bull. Br. Mus. Nat. Hist. (Geol.) 24, 111-213 (1973a).

Miles, R. S. in Interrelationships of Fishes (eds Greenwood, P. H., Miles, R. S. & Patterson, C.) 63-103 (Academic, 1973b).

Miller, R. F., Cloutier, R. & Turner, S. The oldest articulated chon-drichthyan from the Early Devonian period. Nature 425, 501-504 (2003).

Moy-Thomas, J. A. The structure and affi nities of Chondrenchelys problematica Tr. Proceedings of the Zoological Society, Lon-don1935, 391-403 (1935).

Mutter, R. J., de Blanger, K., & Neuman, A. G. Elasmobranchs from the Lower Triassic Sulphur Mountain Formation near Wapiti Lake (BC, Canada). Zoological Journal of the Linnean Society 149, 309-37 (2007).

Mutter, R. J., Neuman, A. G. & de Blanger, K. Homalodontus nom. nov. a replacement for Wapitiodus Mutter, de Blanger and Neu-man 2007 (Homalodontidae nom. nov., ?Hybodontoidea), pre-occupied by Wapitiodus Orchard, 2005. Zoological Journal of the Linnean Society 154, 419-420 (2008).

Nelson, G. J. in Current problems of lower vertebrate phylogeny. (ed. T. Ørvig) 129-143 (Almqvist & Wiksell, Stockholm, 1968).

Newberry, J. S. The Paleozoic fi shes of North America, Monograph of the U.S. Geological Survey 16, 1–340 (1889).

Newman, M. J., Davidson, R. G., den Blaauwen, J. L. & Burrow, C. J. The Early Devonian acanthodian Uraniacanthus curtus (Powrie, 1870) n. comb., from the Midland Valley of Scotland. Geodiversitas 34, 739-759 (2012).

Oelofsen, B. W. A fossil shark neurocranium from the Permo-Car-boniferous (lowermost Ecca Formation) of South Africa. In In-do-Pacifi c fi sh biology. Proceedings of the Second International Conference on Indo-Pacifi c Fishes. Ichthyological Society of Japan, Tokyo, pp. 107-124 (1986).

Patterson, C. The phylogeny of the chimaeroids. Philosophical Transactions of the Royal Society of London, Series B 249, 101-219 (1965).

Patterson, C. Morphology and interrelationships of primitive acti-nopterygian fi shes. American Zoologist 22, 241-259 (1982).

Patterson, C. Interpretation of the toothplates of chimaeroid fi shes. Zool. J. Linn. Soc. 106, 33-61 (1992).

Pearson, D. M. & Westoll, T. S. The Devonian actinopterygian Chei-rolepis Agassiz. Trans. R. Soc. Edinb. 70, 337-399 (1979).

Pradel, A. Skull and brain anatomy of Late Carboniferous Siby-rhynchidae (Chondrichthyes, Iniopterygia) from Kansas and Oklahoma (USA). Geodiversitas 32, 595-661 (2010).

Pradel A., Didier, D., Casane, D., Tafforeau, P. & Maisey J. G. Ho-locephalan embryo provides new information on the evolution of the glossopharyngeal nerve, metotic fi ssure and parachordal plate in gnathostomes. PLoS ONE 8: e66988 DOI:10.1371/jour-nal.pone.0066988 (2013).

Pradel A., Langer M., Maisey J. G., Geffard-Kuriyama D., Cloetens P., Janvier P., & Tafforeau P. Skull and brain of a 300 million-year-old chimaeroid fi sh revealed by synchrotron holotomog-raphy. Proceedings of the National Academy of Sciences 106, 5224-5228 (2009).

Pradel, A., Maisey, J. G., Tafforeau, P., Mapes, R. H. & Mallatt, J. A Palaeozoic shark with osteichthyan-like branchial arches. Na-ture 509, 608-611 (2014).

Pradel, A., Tafforeau, P. & Janvier P. Study of the pectoral girdle and fi ns of the Late Carboniferous sibyrhynchid iniopterygians (Ver-tebrata, Chondrichthyes, Iniopterygia) from Kansas and Okla-homa (USA) by means of microtomography, with comments on iniopterygian relationships. Comptes Rendus Palevol 9, 377-387 (2010).

Pradel A., Tafforeau P., Maisey J. G. & Janvier P. A new Paleo-zoic Symmoriiformes (Chondrichthyes) from the Late Car-boniferous of Kansas (USA) and Cladistic Analysis of Early Chondrichthyans. PLoS ONE 6: e24938 DOI:10.1371/journal.pone.0024938 (2011).

Qu, Q., M., Zhu, M. & Wang, W. Scales and dermal skeletal histolo-gy of an early bony fi sh Psarolepis romeri and their bearing on the evolution of rhombic scales and hard tissues. PLoS One 8,

e61485 (2013).Qiao, T., King B., Long J. A., Ahlberg P. E., & Zhu M. Early gnatho-

stome phylogeny revisited: multiple method consensus. PLoS

ONE 11, DOI:10.1371/journal.pone.0163157 (2016).Reif, W. E. Types of morphogenesis of the dermal skeleton in fossil

sharks. Paläont. Z. 52, 110-128 (1978).Reif, W. E. Squamation and ecology of sharks. Cour. Forsch.-Inst.

Senckenberg 78, 1-255 (1985).Rieppel, O. A new genus of shark from the Middle Triassic of Monte

San Giorgio, Switzerland. Palaeontology 25, 399-412 (1982).Schaeffer, B. The xenacanth shark neurocranium, with comments on

elasmobranch monophyly. Bull. Am. Mus. Nat. Hist. 169, 1-66 (1981).

Schultze, H.NP. & Zidek, J. Ein primitiver acanthodier (Pisces) aus dem Unterdevon Lettlands. Paläontologische Zeitschrift 56, 95-105 (1982).

Seidel, R., Lyons, K., Blumer, M., Zalansky, P., Fratzl, P., Weaver, J. C. & Dean, M. N. Ultrastructural and developmental features of the tessellated endoskeleton of elasmobranchs (sharks and rays). J. Anat. DOI:10.1111/joa.12508 (2016).

Solér-Gijon, R. & Hampe, O. Evidence of Triodus Jordan 1849 (Elasmobranchii: Xenacanthidae) in the Lower Permian of the Autun basin (Muse, France). N. Jb. Geol. Paläont. Mh. 1998, 335-348 (1998).

Stahl, B. J. in Handbook of Paleoichthyology Vol. 4 (ed. Schultze, H.-P.) (Friedrich Pfeil, München. 1999).

Turner, S. Middle Palaeozoic elasmobranch remains from Australia. Journal of Vertebrate Paleontology 2, 117-131 (1982).

Turner, S., Burrow, C. J. & Warren, A. Gyracanthides hawkinsi sp. nov. (Acanthodii, Gyracanthidae) from the Lower Carbonifer-ous of Queensland, Australia, with a review of gyracanthid taxa. Palaeontology 48, 963-1006 (2005).

Valiukevicius, J. in Fossil Fishes as Living Animals (ed. Mark-Kurik, E.) 193-213 (Academy of Sciences of Estonia, Tallinn, (1992).

Warren, A., Currie, B. P., Burrow, C. & Turner, S. A redescription and reinterpretation of Gyracanthides murrayi Woodward 1906 (Acanthodii, Gyracanthidae) from the Lower Carboniferous of the Mansfi eld Basin, Victoria, Australia. Journal of Vertebrate Paleontology 20, 225-242 (2000).

Watson, D. M. S. The acanthodian fi shes. Philosophical Transac-tions of the Royal Society of London B 228, 49-146 (1937).

Williams, M. E. A new specimen of Tamiobatis vetustus (Chondrich-thyes, Ctenacanthoidea) from the Late Devonian Cleveland Shale of Ohio. Journal of Vertebrate Paleontology 18(2), 251-260 (1998).

Williams, M. E. Tooth retention in cladodont sharks: with a compar-ison between primitive grasping and swallowing, and modern cutting and gouging feeding mechanisms. Journal of Vertebrate Paleontology 21, 214-226 (2001).

Woodward, A. S. & White, E. I. The dermal tubercles of the Upper Devonian shark, Cladoselache. Annals and Magazine of Natural History 11, 367-368 (1938).

Yu, X. A new porolepiform-like fi sh, Psarolepis romeri, gen. et sp. nov. (Sarcopterygii, Osteichthyes) from the Lower Devonian of Yunnan, China. J. Vertebr. Paleontol. 18, 261-264 (1998).

Zangerl, R. in Handbook of Paleoichthyology Vol. 3A (ed. Schultze, H.-P.) (Gustav Fischer Verlag, Stuttgart,1981).

Zangerl, R. & Case, G. R. Iniopterygia, a new order of chondrich-thyan fi shes from the Pennsylvanian of North America. Fieldi-ana: Geology 6, 1-67 (1973).

Zangerl, R. & Case, G. R. Cobelodus aculeatus (Cope), ananacan-thous shark from Pennsylvanian black shales of North America. Palaeontographica, A, 154, 107-157 (1976).

Zhu, M., Ahlberg, P., Pan, Z., Zhu, Y., Qiao, T., Zhao, W., Jia, L. & Lu, J. A Silurian maxillate placoderm illuminates jaw evolution. Science 354, 334-336 (2016).

Zhu, M. & Schultze, H. P. The oldest sarcopterygian fi sh. Lethaia 30, 293-304 (1997).

Zhu, M. & Schultze, H. P. in Major Events in Early Vertebrate Evo-lution (Palaeontology, phylogeny, genetics, and development). (ed. Ahlberg, P. E.) 289-314 (Taylor and Francis, 2001).

Zhu, M & Yu, X. A primitive fi sh close to the common ancestor of tetrapods and lungfi sh. Nature 418, 767-770 (2002).

Zhu, M., Yu, X, & Ahlberg, P. E. A primitive sarcopterygian fi sh with an eyestalk. Nature 410, 81-84 (2001).

Zhu, M., Yu, X., Ahlberg, P. E., Choo, B., Lu, J., Qiao, Q., Zhao, L. J., Blom, H., & Zhu, Y. A Silurian placoderm with osteich-thyan-like marginal jaw bones. Nature 52, 188-193 (2013).

Zhu, M., Yu, X. & Janvier, P. A primitive fossil fi sh sheds light on the origin of bony fi shes. Nature 397, 607-610 (1999).

165

Chapter IV: Functional Morphology of Symmoriid Jaws

Zhu, M., Zhao, W., Jia, L., Lu, J., Qiao, T. & Qu, Q. The oldest artic-ulated osteichthyan reveals a mosaic of gnathostome characters. Nature 458, 469-474 (2009).

Zidek, J. Late Pennsylvanian Chondrichthyes, Acanthodii, and deep-bodied Actinopterygii from the Kinney Quarry, Manzani-

ta Moutains, New Mexico. In Geology and paleontology of the Kinney Brick Quarry, Late Pennsylvanian, central New Mexi-co. J. Zidek ed. Bulletin 138, New Mexico Bureau of Mines & Mineral Resources (Socorro: New Mexico Bureau of Mines & Mineral Resources), pp. 199-214. (1992).

CONCLUSIONS

169

Conclusions

Alpha diversity and palaeoecology of

the Maïder region of Morocco

Fammenian Fossillagerstätten of the Maïder re-gion contain numerous gnathostome remains of at least one sarcopterygian species, one actinoptery-gian species, four species of placoderms and fi ve species of chondrichthyans. Most of these gnatho-stome remains were excavated from the Thylaco-cephalan Layer, an argillaceous interval of about two meter thickness with numerous small nodules containing mostly carapaces of thylacocephalan arthropods. This layer represents a Konservat-La-gerstätte (conservation deposit; see Chapter II). In this chapter I, I analysed the faunal composition, trophic nucleus, alpha diversity and ecospace oc-cupation of 21 invertebrate associations of early Famennian (17 from Madene el Mrakbib) to mid-dle Tournaisian age (4 from Aguelmous). The spe-cies richness fl uctuated mostly between three and 14 taxa (rarely it comprised up to 24 taxa) and the ecospace occupation fl uctuated between one and 12 three-dimensional modes of life. Within the ecospace, the ratio between pelagic and benthic modes of life varied signifi cantly. In the trophic nucleus, there were mostly pelagic but also some benthic taxa.

The mostly relatively low taxonomic di-versity and the dominance of pelagic or benthic taxa tolerating dysoxic conditions show that the environment of the Famennian and Tournaisian was characterised by often oxygen-depleted bot-tom-waters in the Maïder Basin (at least in the studied localities). Some of the fl uctuations in ecospace occupation and species richness cor-relate with Famennian and Tournaisian bio-events of varying importance and changes in regional or global sea level including the consequences for oxygen supply to bottom waters. Since the fl ucta-tions in the associations in combination with the changes in the sediment (varying content of clay and carbonate), fi t reasonably well with the glob-al sea level curves, the regional sea level curve of the Maïder was probably more fl uctuant than reported by previous studies. The Famennian eco-space was also more depleted after the Kellwass-er Event (late Frasnian) and during the Annulata Event (middle Famennian). In general, the envi-ronment in which the gnathostomes of the Maïder lived was not suitable for a highly diverse ecosys-tem (common hypoxic to dysoxic conditions, low taxonomic richness, scarcity of benthos, several bio-events), which is also shown by the relatively low diversity of jawed fi sh (around 8, possibly 10 species) and the complete lack of benthic gnatho-

stomes (in the neighbouring Tafi lalt region, teeth of 17 chondrichthyan taxa including pelagic and benthic taxa occur). The chondrichthyans of the Maïder are most abundant in the Thylacocephalan Layer with thylacocephalans as an important food source.

Taphonomy of the Moroccan Fossillag-

erstätte

The mineral composition of fossils of some De-vonian Fossillagerstätten of the eastern Anti-At-las was analysed. Cephalopods, thylacoephalan and vertebrate skeletal remains contain calcite, goethite and sometimes haematite. Bones of plac-oderms and the cartilage of chondrichthyans are preserved in hydroxyapatite and, muscle fi bres of the chondrichthyans contain goethite and hae-matite among other iron minerals; these fossils were likely primarily preserved in pyrite that later weathered into iron oxides and hydroxides.

The occurrence of iron oxides and hydrox-ides (and possibly primary pyrite), the clayey fa-cies and the few benthic invertebrate taxa (ben-thic chondrichthyans are completely absent) in the gnathostome bearing Thylacopehalan Layer suggests that the fossils were embedded under ox-ygen-depleted conditions. These low oxygen-con-ditions might have been caused by the limited water exchange due to the restricted palaeogeog-raphy of the Maïder Basin, which was bordered by land and two pelagic submarine ridges.

Because of the often exceptional fossil pres-ervation (including soft-tissue in, e.g., chondrich-thyans), the faunal composition (few benthos), the abundance of primary pyrite and phosphates and the palaeogeography of the Maïder region, the Famennian Thylacocephala Layer represents the fi rst Devonian Konservat-Lagerstätte of North Africa.

Famennian chondrichthyans of the

Famennian Konservat-Lagerstätte of

the Maïder

Two of the at least fi ve chondrichthyan species discovered in the Famennian Konservat-Lager-stätte were described in the framework of this the-sis. The Famennian Phoebodus saidselachus sp. nov. is the fi rst Phoebodus specimen preserving body remains (Chapter III). Before this discovery,

170

Conclusions

this well-known geographically widely distribut-ed Devonian taxon was exclusively based on teeth and tentatively assigned isolated fi n spines. The anatomy of Phoebodus saidselachus sp. nov. and of the stratigraphically younger phoebodont Thr-inacodus gracia (Carboniferous of Bear Gulch) show that phoebodontids are a chondrichthyan clade characterised by slender and elongate eel-shaped bodies. In the more derived genus Thrina-codus, the degree of elongation is more extreme than in Phoebodus, which corroborates earlier assumptions on the phylogenetic relationships between the two genera based on teeth. Addition-ally, the phylogenetic analyses confi rmed that the Phoebodontidae are stem elasmobranchs, which encompasses both genera. Since phoebodontid teeth are known from the Givetian (Middle Devo-nian), the phoebodontids and in particular Phoe-bodus represent the earliest stem elasmobranchs and also the oldest anguilliform chondrichthyans.

The second chondrichthyan described from the Fossillagerstätte of the Maïder is the sym-moriiform Ferromirum oukherbouchi gen. et sp. nov (Chapter IV). It is a single specimen with preserved body outline and visceral skeleton, shoulder girdles and fi n spine in three-dimension-al preservation. The virtual 3D-reconstruction of the specimen revealed that this specimen has the best preserved jaws of symmoriiform chondrich-thyans currently known. Based on mechanical

experiments with 3D-prints, the jaw function of a symmoriid could be reconstructed for the fi rst time. Due to the confi guration of the articulation, the lower jaw rotated laterally outward when the mouth opened. As a result of this lateral rotation, more teeth became exposed and thus functional than originally thought. In contrast to the apheto-hyoidean hypothesis (no suspensory function of the hyoid) where a gap exists between the jaws and branchial arches, the hyoid and ceratohyal are tightly articulated with the jaws in Ferromirum. Therefore, the hyoid functioned as a suspension between the jaws and the neurocranium. The jaw function mentioned above and the suspensory function of the hyoid might have been common in symmoriiforms as their jaw-to-skull articulation is a conservative feature in these chondrichthyans (as has been shown by the perfect fi t of the up-per jaws of Ferromirum to the neurocranium of Dwykaselachus).

To conclude, the chondrichthyans preserved in nodules of the Famennian Konservat-Lager-stätte of the Maïder Basin provided new insights into the morphological disparity of Devonian chondrichthyans (in the case of Phoebodus said-selachus sp. nov) and they also allow us to recon-struct the function of certain skeletal elements (suc h as in Ferromirum oukherbouchi gen. et sp. nov.).

APPENDIX A

Collaborations with other projects

(abstracts)

173

Appendix A

THE OLDEST GONDWANAN CEPHALOPOD

MANDIBLES (HANGENBERG BLACK SHALE, LATE

DEVONIAN) AND THE MID-PALAEOZOIC RISE OF

JAWS

by CHRISTIAN KLUG1 , LINDA FREY1 , DIETER KORN2 , ROMAIN JATTIOT1 and

MARTIN R €UCKLIN3

1Pal€aontologisches Institut und Museum, Universit€at Z€urich, Karl Schmid-Strasse 4, CH-8006, Z€urich, Switzerland; chklug@pim.uzh.ch, linda.frey@pim.uzh.ch,

romain.jattiot@pim.uzh.ch2Museum f€ur Naturkunde Berlin, Leibniz-Institut f€ur Evolutions- und Biodiversit€atsforschung, Invalidenstraße 43, D-10115, Berlin, Germany;

dieter.korn@mfn-berlin.de3Naturalis Biodiversity Center, Postbus 9517, 2300 RA, Leiden, The Netherlands; martin.rucklin@naturalis.nl

Typescript received 4 April 2016; accepted in revised form 3 June 2016

Abstract: It is widely accepted that the effects of global

sea-level changes at the transition from the Devonian to the

Carboniferous are recorded in deposits on the shelf of north-

ern Gondwana. These latest Devonian strata had been

thought to be poor in fossils due to the Hangenberg mass

extinction. In the Ma’der (eastern Anti-Atlas), however, the

Hangenberg Black Shale claystones (latest Famennian) are

rich in exceptionally preserved fossils displaying the remains

of non-mineralized structures. The diversity in animal

species of these strata is, however, low. Remarkably, the

organic-rich claystones have yielded abundant remains of

Ammonoidea preserved with their jaws, both in situ and iso-

lated. This is important because previously, the jaws of only

one of the main Devonian ammonoid clades had been found

(Frasnian Gephuroceratina). Here, we describe four types of

jaws of which two could be assigned confidently to the

Order Clymeniida and to the Suborder Tornoceratina. These

findings imply that chitinous normal-type jaws were likely to

have already been present at the origin of the whole clade

Ammonoidea, i.e. in the early Emsian (or earlier). Vertebrate

jaws probably evolved prior to the origin of ammonoids, in

the Early Devonian. The temporal succession of evolutionary

events suggests that it could have been the indirect positive

selection pressure towards strong (and thus preservable) jaws

since defensive structures of potential prey animals would

otherwise have made them inaccessible to jawless predators

in the course of the mid-Palaeozoic marine revolution. In

this respect, our findings reflect the macroecological changes

that occurred in the Devonian.

Key words: Cephalopoda, Ammonoidea, mass extinctions,

macroecology, Devonian, Morocco.

[Palaeontology, 2016, pp. 1–19]

174

Appendix A

�������������� �������������� ���� �

�������� �� ������ �������������� ����������� �� ������� ������ ��

During the Palaeozoic, a diversification in modes of life occurred that included a wide range of predators. Major

macroecological events include the Cambrian Explosion (including the Agronomic Substrate Revolution and the here

introduced ‘Ediacaran-Cambrian Mouthpart Armament’), the Great Ordovician Biodiversification Event, the

Palaeozoic Plankton Revolution, the Siluro-Devonian Jaw Armament (newly introduced herein) and the Devonian

Nekton Revolution. Here, we discuss the evolutionary advancement in oral equipment, i.e. the Palaeozoic evolution of

mouthparts and jaws in a macroecological context. It appears that particularly the latest Neoproterozoic to Cambrian and

the Silurian to Devonian were phases when important innovations in the evolution of oral structures occurred. • Key

words: Gnathostomata, Cephalopoda, evolution, convergence, diversity, nekton, jaws.

CHRISTIAN KLUG, LINDA FREY, ALEXANDER POHLE, KENNETH DE BAETS & DIETER KORN 2017. Palaeozoic evolu-

tion of animal mouthparts. Bulletin of Geosciences 92(4), 511–524 (4 figures, 1 table). Czech Geological Survey,

Prague. ISSN 1214-1119. Manuscript received November 10, 2016; accepted in revised form September 22, 2017; pub-

lished online December 6, 2017; issued December 31, 2017.

Christian Klug, Linda Frey & Alexander Pohle, Paläontologisches Institut und Museum, Universität Zürich, Karl

Schmid-Strasse 4, 8006 Zürich, Switzerland; chklug@pim.uzh.ch, linda.frey@pim.uzh.ch, alexander.pohle@pim.uzh.ch

• Kenneth De Baets, GeoZentrum Nordbayern, Fachgruppe PaläoUmwelt, Universität Erlangen, Loewenichstr. 28,

91054 Erlangen, Germany; kenneth.debaets@fau.de • Dieter Korn, Museum für Naturkunde, Leibniz-Institut für Evolu-

tions- und Biodiversitätsforschung, Invalidenstraße 43, 10115 Berlin, Germany; dieter.korn@mfn-berlin.de

APPENDIX B

Additional article published during doctoral studies

Intraspecifi c variation in fossil vertebrate populations: Fos-

sil killifi shes (Actinopterygii: Cyprinodontiformes) from the

Oligocene of the Central Europe

Linda Frey, Erin E. Maxwell and Marcelo R. Sánchez-Villagra

Published in: Palaeontologia Electronica, 19.2.14A: 1-27

palaeo-electronica.org/content/2016/1464-fossil-killifi shes-from-europe

177

Appendix B

Palaeontologia Electronica

Palaeontologia Electronica

Prolebias rhenanus

Pr. stenoura

Paralebias cephalotes

Prolebias

Paralebias Prolebias

Paralebias cephalotes.

Prolebias Prolebias

Paralebias

178

Appendix B

Prolebias rhenanus

Pr. stenoura

Paralebias cephalotes

Pa. cephalotes

179

Appendix B

Kenyaichthys

kipkechi Kenyaichthy;

Thaumaturus

intermedius,

Atractosteus

messelensis

Lepisosteus

bemisi,

Atractosteus

simplex, A.

messelensis, A.

atrox, Cuneatus

cuneatus,

Cuneatus wileyi

Amyzon

aggregatum

Scaumenacia

curta

Semionotus

Semionotus

Gasterosteus

doryssus

Kerocottus

divaricatus

K. pontifex,

K. hypoceras,

Kerocottus

Myoxocephalus

idahoensis

180

Appendix B

Prolebias

rhenanus Pr. stenoura

Paralebias cephalotes

Paralebias cephalotes

181

Appendix B

Prolebias rhenanus

Pr. stenoura Paralebias cephalotes

182

Appendix B

Prolebias rhenanus

Prolebias

rhenanus

Prolebias

stenoura

Prolebias stenoura

Para-

lebias cephalotes

Paralebias cephalotes

Pa. cephalotes

Prolebias rhenanus Pr stenoura Paralebias cephalotes

Prolebias rhenanus Prolebias stenoura

(n = 40)

Paralebias cephalotes

183

Appendix B

Prolebias sten-

oura

Problebias rhenanus

Paralebias cephalotes

Pro-

lebias rhenanus Pr. stenoura Paralebias cephalotes

184

Appendix B

Prolebias rhenanus Pr. stenoura Paralebias cephalotes

185

Appendix B

Prolebias rhenanus

P

P

Prolebias stenoura

P

P

Paralebias cephalotes

P

P

Prolebias rhenanus

S

P

Prolebias rhenanus Prolebias stenoura Paralebias cephalotes

186

Appendix B

S P

S P S P S

P

S

P

Prolebias stenoura

S P

S P

Paralebias cephalotes

S P

S P

S

Prolebias rhenanus.

Prolebias stenoura.

187

Appendix B

S P

Prolebias

Pr. stenoura

Pr. stenoura

Pr. rhenanus

Para-

lebias cephalotes Prolebias

Paralebias

Prolebias

Pa. cephalotes

Pa. cephalotes

P Pr. stenoura

P

Paralebias cephalotes

Prolebias

Pr. rhenanus Pr. sten-

oura

Paralebias cephalotes.

188

Appendix B

Prolebias rhenanus Paralebias cepha-

lotes

Pr. stenoura

Problebias

Prolebias Prolebias

rhenanus P Pr.

stenoura P

Paralebias cephalotes P

Pro-

lebias

Prolebias rhenanus

Pr. stenoura

Gambusia quadruncus

Xenoophorus

Gambusia,

189

Appendix B

Paralebias

Prolebias

Recherches sur les poissons

fossiles.

Biological Journal of the Linnean Society,

Galaxias platei. Journal of Fish Biology,

Canadian Journal of Earth Science,

Copeia,

Paleobiology,

Paleobiol-

ogy,

Gasterosteus

doryssus Paleobiology,

Systematic Zoology,

Alioramus altai

PLoS ONE

, Danio

rerio Developmental

Dynamics,

Paleobiology,

Copeia,

Paleobiology,

Lucania parva

190

Appendix B

The Southwestern Naturalist

Scaumenacia curta

Geodiversitas,

Salvelinus alpinus

International Journal of

Zoology,

Journal of Biogeography

Zoological Journal of

the Linnean Society

Vertebrate Zoology,

Paleobiology,

Aphanius

Folia Zoologica

Lebias fasciata

Italian Journal of Zoology

Aphanius fasciatus

Journal of Fish Biology

Evolution and Development,

Xenoophorus

Occasional Papers of the

Museum of Zoology,

PLoS ONE

Nature,

Evolution,

Aus-

trolebias

Biological Journal of the

Linnean Society

Géobios,

Prolebias

rhenanus Sciences géologique Bulletin,

Comptes rendus de

l`Académie des Sciences Paris

Aphanius

Prolebias egeranus Journal of the

National Museum (Prague), Natural History Series

Prolebias stenoura

Pro-

lebias

Geodiversitas,

Paralebias Neues

Jahrbuch für Geologie und Paläontologie Abhand-

lung,

Bulletin du Service de la Carte

géologique de France,

Bulletin du Bureau de Recherche

géologique minière,

Philosophical Transactions of the Royal Society B,

Copeia

191

Appendix B

Society

of Vertebrate Paleontology Memoir,

Developmental

Dynamics,

Variation: A Cen-

tral Concept in Biology

Palaeontologia Electronica

Ecology Letters,

Journal of Paleontology,

Evolution,

Fishes of the Great

Lakes region

Lucania parva

Miscellaneous Publications, Museum

of Zoology, University of Michigan

Paleobiology,

Pale-

obiology,

Paleobiology,

Science,

Bulletin of the Japanese Society of Scientific Fisher-

ies,

Manticoceras

Cephalopods Present and Past: New Insights and

Fresh Perspectives.

Dikelocephalus

Journal

of Paleontology,

Journal of Paleontol-

ogy,

Gambusia quadruncus

Journal of Fish Biology

Progonomys

Paleobiology,

Journal of the Fisheries Research Board of Canada,

Fish Physiology Volume XI-B

Neues Jahrbuch

der Geologie und Paläontologie Abhandlungen,

The Evolution of Perisso-

dactyls.

Onohippidium

Journal of Vertebrate Paleon-

tology,

Salmo gaird-

neri Environmental Biology of Fishes,

Aphanius fasciatus

Oceanologica Acta,

Journal of Experimental Zoology

(Molecular and Developmental Evolution),

Paleobi-

ology,

192

Appendix B

BMC Evolutionary

Biology,

Animal Species and Evolution.

Oecologia,

Semionotus

Evolution,

Paleobiology,

Environmental Biology of

Fishes,

Integrative

and Comparative Biology,

Agaricocrinus

Journal of Paleontology,

Mesozoic Fishes 3 - Systematics,

Paleoenvironments and Biodiversity.

Feuille des Jeunes Naturalists, 23e année

(1892-1893)

Acrochordiceras

Palae-

ontology,

Coregonus lavaretus Acta

Biologica Cracoviensia Series Zoologia,

Fishes of the World

Aphanius fasciatus

Copeia

Revue des Sciences naturelles

d`Auvergne,

Paleo-

biology,

Syntarsus rhodesiensis

Dinosaur Systematics:

Approaches and Perspectives.

Aphanius Prolebias

Journal of Morphology

Notho-

branchius PLoS

ONE

Evolution,

Bulletin de la Société d`Histoire

naturelle de Toulouse,

Evolutionary Biology,

Pun-

gitius pungitius Biological Journal of the Linnean

Society,

The Major Features of Evolution.

Palaios,

Journal of the Fisheries Research Board of

Canada

Aphanius fasciatus

Nova Thalassia

Aphanius fasciatus

Animalia

Aphanius fasciatus

Italian Journal of Zoology

Aphanius fasciatus

Journal of Morphology

Integrative and Comparative Biology,

193

Appendix B

Zoology,

American Zoologist,

Science

Olenellus gilberti

Journal of

Systematic Palaeontology

Acta Zoologica,

Evolutionary Ecology

Menidia

Copeia,

Bio-

logical Journal of the Linnean Society,

194

Appendix B

Prolebias rhenanus

195

Appendix B

196

Appendix B

Prolebias stenoura

197

Appendix B

Paralebias

cephalotes

198

Appendix B

199

Appendix B

200

Appendix B

201

Appendix B

203

ACKNOWLEDGMENTS

205

Acknowledgments

I would like to show my greatest appreciation to my supervisor Prof. Dr. Christian Klug (University of Zurich) for his support, patience and encouragements and for sharing his knowledge about the palaeon-tology of Morocco during the work on my dissertation. Without his guidance, this dissertation would not have been possible.

I greatly thank Prof. Dr. Michael Coates (University of Chicago) and Dr. Martin Rücklin (Naturalis Bio-diversity Center, Leiden) for accepting to be committee members and for the illuminating discussions, inputs and feedbacks. Many thanks go to Prof. Dr. Marcelo Sánchez and to Prof. Dr. Hugo Bucher for providing me work space and constructive feedbacks during committee meetings.

During this dissertation, I received generous support from many colleagues and therefore, I would like to thank:

The colleagues of the Ministère de l’Energie, des Mines, de l’Eau et de l’Environnement (Direction du Développement Minier, Division du Patrimoine, Rabat, Morocco) for providing working and sample export permits,

Said Oukherbouch (Tafraoute, Morocco) for his enormously important help and support during fi eld work,

Michał Ginter (University of Warsaw) and Vachik Hairapetian (Islamic Azad University of Isfahan) for sharing their knowledge o n early chondrichtyan teeth,

René Kindlimann (Aathal) and Jorge Carrillo-Briceño (University of Zurich) for sharing their exper-tise on fossil and recent cartilagenous fi sh,

Dieter Korn (Museum für Naturkunde, Berlin) for sharing his knowledge on the diversity of Devo-nian ammonoids, for providing data for palaeoecological analyses and for giving constructive feed-backs,

Michael R. W. Amler (University of Cologne) for helping in the determination of Devonian bivalves, Per Ahlberg (University of Uppsala) for advice about 3D-reconstruction software, Christina Brühwiler (Winterthur), Ben Pabst (Zurich), Claudine Misérez (Neuchâtel) and the Tahiri

Museum (Erfoud) for their excellent fossil preparation, Rosi Roth (University of Zurich) for preparing fossil material and for helping in the photo lab. Markus Hebeisen (University of Zurich) for providing working space in his preparation lab and for

introducing me into preparation with airscribes, Alexander Pohle (University of Zurich) for conducting XRD-analyses, Lydia Zehnder and Sebastian Cionoiu (both ETH Zurich) for their generous help with the XRD- and

Raman-analyses, Iwan Jerjen (ETH Zurich), Tom Davis (University of Bristol), Alexandra Wegemann (University of

Zurich) and Anita Schweitzer (Zurich) for acquiring computer tomography scans of the specimens, Thodoris Argyriou (Paris) for sharing his knowledge about fi shes, for CT-scanning and assisting

during virtual 3D-reconstruction, Amane Tajika (NHM, New York) and Tobias Reich (University of Zurich) for kindly providing help

during segmentation of CT-scans, Gabriel Aguirre-Fernández (University of Zurich) for introducing me into software used for phyloge-

netic analysis, Morgane Brosse (Zurich) for generously helping me to solve any problem concerning the layout of

this disseration, and Heike Götzmann as well as Heinrich Walter (both University of Zurich) for their administrative and

technical support.

I would also like to thank all the colleagues of the Palaeontological Institute and Museum of the Univer-sity of Zurich not only for their scientifi c advices and support but also for their friendship. Moreover, I would like to show my appreciation to the people I met in Morocco for their hospitality, which made our fi eld trips very pleasant.

A big thank you goes to my family, especially to my parents Edith and Peter and to my grandmother Ma-rie Anne who always supported me during my studies.

206

Acknowledgments

Funding

I greatly appreciate the fi nancial support of this dissertation by the Swiss National Science Founda-tion (No. 200021_156105)

The Swiss Geological Society supported the participation at 14th International Symposium on Early and Lower Vertebrates in Poland in 2017.

207

CURRICULUM VITAE

208

Curriculum Vitae

Name: FreyFirst name: LindaDate of birth: 10.07.1987Nationality: SwissHeimatort: St. Ursen (FR)

Education

2003 –2007 Kantonsschule Wettingen

2007 –2011 University of Zurich, Bachelor of Science Main subject: Biology

2012 –2013 University of Zurich, Master of ScienceMaster thesis in Palaeontology:Alpha diversity and palaeoecology of invertebrate associations of the Early Devonian in the Moroccan Anti-Atlas (Grade: 5.7) Supervisor: Prof. Dr. Christian Klug

Since 2014 PhD student in Palaeontology Palaeontological Institute and Museum, University of Zurich Supervisor: Prof. Dr. Christian Klug

Publications during doctoral studies

Articles

Frey, L., Rücklin, M., Korn, D. and Klug, C. (2018): Late Devonian and Early Carboniferous alpha diversity, ecospace occupation, vertebrate assemblages and bio-events of southeastern Morocco. Palaeogeography, Palaeoclimatology, Palaeoecology, 496 (1): 1-17;

Klug, C., Frey, L., Pohle, A., De Baets, K. and Korn, D. (2017): Palaeozoic evolution of animal mouthparts. Bulletin of Geosciences, 92(4): 13 pp.

Klug, C., Frey, L. Korn, D., Jattiot, R. and Rücklin, M. (2016). The oldest Gondwanan cephalopod mandibles (Hangenberg black shale, Late Devonian) and the mid-Palaeozoic rise of jaws. Palaeontology: 1-19 pp., doi: 10.1111/pala.12248

Frey, L., Maxwell, E., and Sánchez-Villagra, M. R. (2016): Intraspecifi c variation in fossil vertebrate populations: Fossil killifi shes (Actinopterygii: Cyprinodontiformes) from the Oligocene of Central Europe. Palaeontologia Electronica 19.2.14A: 1-27; palaeo-electronica.org/content/2016/1464-fossil-killifi shes-from-europe

Abstracts

Klug, C., Frey, L., Pohle, A., De Beats, K. & Korn, D. (2018b): Palaeozoic evolution of cephalopod mouthparts. 10th International Symposium on Cephalopods - Present and Past: p. 2, Fez.

Frey, L., Coates, M., Ginter, M., Klug, C. (2017): Skeletal Remains of Phoebodus politus Newberry 1889 (Chondrichthyes: Elasmobranchii) from a Famennian Konservatlagerstätte in the Eastern Anti-Atlas (Morocco) and its Ecology. 15th Annual Meeting of the European Association of Vertebrate Palaeontologists; p. 37, Munich.

209

Curriculum Vitae

Frey, L., Coates, M., Ginter, M., Klug, C. (2017): Skeletal remains of Phoebodus politus Newberry 1889 (Chondrichthyes: Elasmobranchii) from a Famennian Konservatlagerstätte in the eastern Anti-Atlas (Morocco) and its ecology. 14th International Symposium on Early and Lower Vertebrates : p. 36, Checiny, Poland.

Klug, C., Frey, L., Pohle, A., Rücklin, M., (2017): Origin of the Konservatlagerstätten of the southern Maider (Morocco) and gnathostome preservation. 14th International Symposium on Early and Lower Vertebrates: p. 52, Checiny, Poland.

Frey, L., Coates, M., Ginter, M., Klug, C. (2016): The fi rst skeletal remains of Phoebodus politus Newberry 1889 (Chondrichthyes: Elasmobranchii) and its ecology. 14th Swiss Geoscience Meeting, 4. Palaeontology: p. 147, Geneva.

Klug, C., Frey, L., Korn, D., Jattiot, R., Rücklin, M. (2016): No fossil record? Yes fossil record! Konservat-Lagerstätten of the End-Devonian Hangenberg Black Shale in the eastern Anti-Atlas (Morocco). 14th Swiss Geoscience Meeting, 4. Palaeontology: p. 149, Geneva.

Klug, C., Frey, L., De Baets, K., and Korn, D. (2016): Paleozoic Marine macroecology. 1st Meeting of Early Stage Researchers in Palaeontology: p. 1, Alpuente (Valencia).

Frey, L., Rücklin, M., Kindlimann, R., and Klug, C. (2015): Alpha diversity and palaeoecology of a Late Devonian Fossillagerstätte from Morocco and its exceptionally preserved fi sh fauna. 13th Swiss Geoscience Meeting: p. 142, Basel,

Klug, C., Frey, L. and Rücklin, M. (2015): Preservation and taphonomy of Famennian Fossillagerstätten in the eastern Anti-Atlas of Morocco. 13th Swiss Geoscience Meeting: p. 144, Basel.

Frey, L., Rücklin, M., Kindlimann, R., and Klug, C. (2015): Alpha diversity and palaeoecology of a Late Devonian Fossillagerstätte from Morocco and its exceptionally preserved fi sh fauna. 13th International symposium on Early and Lower Vertebrates: p. 15, Melbourne

Klug, C., Frey, L. and Rücklin, M. (2015): Preservation and taphonomy of Famennian Fossillagerstätten in the eastern Anti-Atlas of Morocco. 13th international Symposium on Early and Lower Vertebrates: p. 21, Melbourne.