Records of the Western Australian Museum Supplement No. 57: 157-168 (1999).

Biogeographic affinities of Middle and Late Devonian fishesof South Africa

M. Eric Andersonl, John A. Long2, Fiona J. Evans3

, John E. Almond4, Johannes N. Theron4

and Patrick A. BenderS

1 J.L.B. Smith Institute of Ichthyology, Private Bag 1015, Grahamstown 6140, South Africa; email: IHMA@giraffe.ru.ac.za2 Western Australian Museum, Francis St, Perth, WA 6000, Australia

3 Department of Zoology, University of Stellenbosch, Private Bag Xl, Matieland 7602, South Africa4 Council for Geoscience, PO Box 572, Bellville 7535, South Africa

5 Museum of the Council for Geoscience, Private Bag X112, Pretoria 0001, South Africa

Abstract - South African fossil fish remains spanning much of the DevonianPeriod have now been reported from the Bokkeveld and Witteberg Groups(West Gondwana). Emsian and Eifelian material is scarce, consisting offragments of an antiarch, elasmobranchs, the acanthodian Machaeracanthllsand a possible dipnoan, represented by a single scale. Recent explorationshave focused on Middle Devonian (Givetian) and Late Devonian (Famennian)sites in the south and west of the country. The Givetian ichthyofauna ischaracterized by a high proportion of sharks to placoderrns and an absence ofagnathans, actinopterygians and dipnoans, with only a single crossopterygian(Onychodlls sp.).

The better-explored Famennian has a high diversity of endemic forms, andat higher taxonomic levels is comparable to ichthyofaunas from slightlyearlier sites in Iran and at Mount Howitt, Australia, reflecting the pan­Gondwanan nature of non-marine fish distributions in the Late Devonian.The Givetian, however, in its diversity of sharks, comparable to that ofAntarctica, and absence of thelodonts, antiarchs and major sarcopterygiangroups, is interpreted as a depauperate assemblage unaffected bycosmopolitan distributional trends occurring at the time. Three possibleexplanations are a high-latitude effect, palaeoecological restriction in brackishmarginal habitats, or inadequate sampling of the fauna.

INTRODUCTIONDevonian fish faunas of West Gondwana were

reviewed by Lelievre et al. (1993), althoughgenerally few remains were known at the time. Forthe South African region, these authors cited aMiddle Devonian assemblage of only five taxa, firstreported by Chaloner et al. (1980). Many moreDevonian fish remains spanning the Emsianthrough Famennian epochs have been reportedfrom South Africa (Oosthuizen 1984; Anderson etal. 1994; Gess and Hiller 1995; Long et al. 1997; Longet al. in press), yet scant or no reference to thematerial has been cited by authors. The newlydiscovered material comes from one site nearGrahamstown, Eastern Cape, and several in theWestern Cape (Figure 1).

Anderson et al. (1994) first reported on the EasternCape fossil fishes. The site is a Famennian-ageestuarine lagoon in a barrier island complex, part ofthe 1200 km-long outcrop of the WitpoortFormation (Witteberg Group, Cape Supergroup).Hiller (1990) and Taylor and Hiller (1992) discussedthe stratigraphy of the Late Devonian Weltevredeand Witpoort Formations and the local

palaeoecology. Plant and invertebrate remains havebeen found in both formations, but fishes areknown only in the Witpoort (Figures 2, 3; Gess andHiller 1995). Here we emend a few identificationsmade by Anderson et al. (1994; Figure 3 herein; seealso Long et al. 1997).

In 1994 and 1996 J.A. Long visited South Africa toaid in describing the new material. The authors ofthe present paper embarked on a two-weekcollecting expedition to sites in the youngerBokkeveld Group (Cape Supergroup) of theWestern Cape Province in September 1996. Thisresulted in the most comprehensive collection ofMiddle Devonian fishes ever made in South Africa,producing a preliminary list of nine taxa (Table 1;Long et al. in press). Several sites were visited, butcollections centred around Warmwaterberg nearLadismith (Figure 4) and in the Cederberg Rangenear Grootrivier (Figure 5). These are characterizedby mudstones, silts tones and lag conglomerates ofdeltaic environments (Theron and Loock 1988). Themixed fish fauna (Figure 6) and associated biotareflect habitats of fluctuating salinities.

Long et al. (in press) reviewed the presently

158 M.E. Anderson, J.A. Long, F.J. Evans, J.E. Almond, J.N. Theron, P.A. Bender

IWITTEBERG GROUP

BOKKEVELD GROUP

:::::::.:::::::::: TABLE MOUNTAIN GROUP." ....

o 100 200km

Figure 1 Map showing the distribution of the Bokkeveld and Witteberg Groups (Cape Supergroup) in South Africa.Abbreviations for fossil fish localities: BH = Baviaanshoek; GR = Grootrivier; GT = Grahamstown; HS =Hondewater Stasie; LF = Leeubosfontein; LH = Leeuwenhoek; PH = Plathuis; SV = Swartzvlei; TB = DeDooms Tafelberg; VK = Vaalbokskloof; WB = Warrnwaterberg.

known South African Devonian ichthyofauna.However, as they only briefly touched uponbiogeographic issues, we expand upon this subjecthere. As only the Givetian and Farnennian epochsare represented by repeatedly collected taxa, wewill restrict the discussion to the fish fauna of the

Figure 2 Excavating the Witpoort shale horizon atGrahamstown.

Klipbokkop and Adolphspoort Formations(Givetian; Western Cape) and the WitpoortFormation (Farnennian; Eastern Cape).

THE ICHTHYOFAUNA

Chondrichthyes

GivetianOelofsen (1981) first reported Devonian shark

material from South Africa as tooth impressionsfrom the Bokkeveld Group in the collection ofAbraham H. De Vries from his farm nearWarmwaterberg. Oelofsen mistakenly referred tothe fossil horizon as the "third shale" of theBokkeveld succession. This, however, is theEifelian-age Tra Tra Formation of the WesternCape. The fossiliferous horizon at the De Vries farmlies within the younger Adolphspoort Formation(above). These "pleuracanth (ctenacanth)-type"teeth in fact represent Antarctilamna, referred to as a"stem-group xenacanth" by Long and Young (1995),but which may actually be a phoebodont (0.Hampe personal communication 1997).Antarctilamna teeth were collected in theAdolphspoort and Klipbokkop Formations by us aswell, and Long et al. (in press) noted differencesfrom the type species, A. prisca, from Antarctica.Other Antarctilamna teeth are known from SouthAmerica, Iran, Saudi Arabia and Australia,spanning the Emsian/Eifelian to the Givetian(Lelievre et al. 1993; J.A. Long unpublishedobservations). Teeth of the sharks Aztecodus andPortalodus were also found by us in the KlipbokkopFormation. These and Antarctilamna are known to

Biogeography of South African Devonian fish 159

6

Figure 3 Reconstruction of the Famennian ichthyofauna of Grahamstown, Eastern Cape. Numerically dominant wereplacoderms and acanthodians. Placoderms include the antiarch Bothrio/epis africana (1), the groenlandaspididarthrodires Groenlandaspis riniensis (2) and Africanaspis doryssa (3), and an unidentified ptyctodont (4). Anundetermined species of gyracanthid acanthodian was also common (5). Less abundant were coelacanthsclose to Dip/ocercides (6), a stem-group chondrichthyan (7; see Anderson et al. this volume), a large, perhaps 2m long, tristichopterid sarcopterygian close to Ellsthenodon (8), a lungfish close to Andreyevichthys, if not ofthat genus (9), and unidentified palaeoniscoid actinopterygians (10).

co-occur elsewhere only in the Aztec Siltstone,Antarctica (latest Givetian).

FamermianAnderson et al. (1994) first reported on the single

known chondrichthyan from the WitpoortFormation, an entire specimen plus an isolatedspine of another (see Anderson et al. this volume).At first regarded as a possible holocephalan(Anderson et al. 1994), it is now thought to be a very

primitive basal chondrichthyan relict with noknown close affinities (Anderson et al. this volume).

Placodermi

GivetianThree phlyctaenioid arthrodires, all from different

families, are known in the fauna: Graenlandaspistherani (Groenlandaspididae), an unidentifiedphlyctaeniid, and an unidentified holonematid.

160 M.E. Anderson, J.A. Long, F.J. Evans, J.E. Almond, J.N. Theron, P.A. Bender

Figure 4 The Adolphspoort Formation at Hondewater Stasie near Ladisrnith.

Several distorted skulls of a Groenlandaspis werecollected by us in the Adolphspoort Formation, butit is presently unknown if these or the trunk armourof Chaloner et al. (1980, figure 8A) represent G.theroni or another species. Long et al. (in press)discussed identification problems owing to angularshear on the mudstone, which led to G. theroni beingplaced in a monotypic genus, Barrydalaspis by

Chaloner et al. (1980). Groenlandaspis occurs fromthe late Emsian in Iran and Australia to the lateFamennian in Greenland, Australia and SouthAfrica. Perhaps the most speciose arthrodire genus,its members occur in both marine and freshwaterdeposits, making it a poor indicator of habitat type.

Long et al. (in press) also reported additionalarmour of a long-shielded phlyctaeniid first noted

Figure 5 The Klipbokkop Formation (arrow) at Grootrivier, Cederberg Range.

Biogeography of South African Devonian fish 161

Figure 6 Reconstruction of the Givetian ichthyofauna of the Western Cape. Relatively low in diversity at highertaxonomic levels, it was dominated by sharks such as Antarctilamna (1) and other early xenacanthimorphs, aswell as c1imatiiform acanthodians such as Gyracanthides (2) and an unidentified c1imatiiform (3). Lessabundant were arthrodires such as Groenlandaspis theroni (4), an unidentified holonematid (5) and anunidentified phlyctaeniid (6). A single sarcopterygian, Onychodlls sp. (7) is also known.

by Chaloner et al. (1980, figure 5), hinting that thisform may prove to be an undescribed genus oncemore material was studied. The Phlyctaeniidae, asreclassified by Goujet (1984), ranged throughout theOevonian from the Siegenian to the Frasnian inEuramerica, northern (Saudi Arabia, Iran) andeastern (Aztec Siltstone) Gondwana (Blieck et al.1980; Young 1989; Lelievre et al. 1993). Thus, this isthe first of the family recorded fromsouthwestern Gondwana. In overall appearance themorphology of the trunk shield approaches that ofthe Frasnian (Oenison 1978, figure390).

The third placoderm in the fauna is representedby a complete jaw set and suborbital plate of apossible new holonematid collected by I.A. Long atGrootrivier. This tantalizingly incomplete specimen

was regarded as intermediate between typicalholonematids, which possess separate anteriordorsolateral (AOL) and posterior dorsolateral (POL)trunk plates and unfused anterior supragnathals("superognathals"), and groenlandaspidids, whichhave AOL and POL plates meeting and with fusedanterior supragnathals (based on Mount Howittspecimens, J.A. Long unpublished observations).The Holonematidae was a marine family accordingto Schultze and Cloutier (1996) which occurred inEuramerica and northern Gondwana, spanningEifelian to Frasnian times.

Famenl1ianTwo groenlandaspidid arthrodires and the first

species of the antiarch genus Bothriolepis fromAfrica, all from the Witpoort Formation, first noted

M.E. Anderson, J.A. Long, F.J. Evans, J.E. Almond, J.N. Theron, P.A. Bender162

Figure 7 Ptyctodontidae gen. et sp. indeterminate,Grahamstown fauna (Famennian WitpoortFormation). Anterior median ventral plate inventral view. Camera lucida sketch. Scale bar=5mm.

by Anderson et al. (1994), were described by Long etal. (1997). Groenlandaspis riniensis bears aresemblance to the Givetian G. antarctica from thefluviatile Aztec Siltstone. The high-crested (mediandorsal plate much higher than long) Africanaspisdoryssa was thought not to be close to other high­crested forms, such as the Emsian EuramericanTiaraspis. However, another high-crested form fromBelgium (Gross 1965) was thought to be congenericwith A. doryssa and Late Devonian in age, althoughDenison (1978) had declared such a late date for thestrata to be "erroneous". The third placoderm,Bothriolepis africana, has a similar preorbital recessmorphology (having a slightly prolongedsemilunate shape) to that of B. barretti from theAztec Siltstone, suggesting the later-occurring B.africana may be derived from some East GondwanaBothriolepis population. A fourth placoderm taxon,the Ptyctodontidae, is represented by just twoanterior median ventral plates (Figure 7). These area highly diagnostic feature for this family (Long1997), and are currently under study by J.A. Long.A putative phyllolepid placoderm, reported to bepresent by Anderson et al. (1994), was later foundon preparation to be Groenlandaspis riniensis. Todate, no definite phyllolepids have been identifiedfrom Africa.

Acanthodii

GivetianTwo species of climatiiform acanthodians are

known from the Adolphspoort and Klipbokkopformations. A single spine of Gyracanthides sp. wasreported by Chaloner et al. (1980), and we havefound additional spines as well as scale impressionsassociated with pectoral fin spines (Long et al. inpress). These remains have close affinity to G.warreni from the Aztec Siltstone, Antarctica, butLong et al. (in press) reserved a specificidentification. Gyracanthides, first described from

fluviatile and lacustrine environments of Victoria,Australia (Woodward 1906), ranged from theGivetian to the Tournaisian (Carboniferous)(Denison 1979). On the De Vries farm(Adolphspoort Formation) near Warmwaterberg,we found a partially articulated acanthodian,possibly representing a climatiiform, without theusual pectoral girdle dermal armour, as occurs inthe genera Kathemacanthus and Cassidiceps fromEuramerica (Gagnier and Wilson 1996). Long et al.(in press) conjectured that our form may representone of these atypical climatiiforms, or may be anischnacanthiform, but more evidence is needed todecide this.

FamennianLarge gyracanthid spines have been collected in

the Witpoort Formation. The longest whole spine is13 cm, but reconstructed lengths of incompletespecimens reach about 20 cm. One scale patchshowing poor detail has recently been collected ­no other material is known. On the basis of the fineribbing and poor tubercle definition, Anderson et al.(1994) were uncertain about the generic identity ofthis form. The presence of gyracanthid remains asbasically isolated spines in an estuarine setting mayreflect washdown from river flooding. Afragmentary, finely-ribbed gyracanthid spine is alsorecorded from a thin channel-Iag conglomeratewithin probable fluvial sandstones of the WitpoortFormation at Soetendals Vlei near Willowmore,Eastern Cape Province. Its stratigraphic positionrelative to the Grahamstown site is unknown.

Sarcopterygii

GivetianA single dentary symphysial tooth whorl of the

basal sarcopterygian Onychodus sp. was collected byus at Grootrivier (Klipbokkop Formation). Asupposed indicator-taxon of marine deposits(Schultze and Cloutier 1996), the familyOnychodontidae is present in Australia in the EarlyDevonian Fairy Beds near Buchan, Victoria, inlimestones at Burrinjuck Dam, New South Wales,and in the Late Devonian at Gogo, WesternAustralia. Also present in Iran in the Middle-LateDevonian, it is absent from both Middle Devoniannon-marine faunas in the Aztec Siltstone,Antarctica, and Mount Howitt, Australia (alongwith other southeastern non-marine Australian fishsites). Another sarcopterygian is possiblyrepresented in the Adolphspoort Formation bysome unidentified head dermal plates in thecollection of J.c. Loock, University of the OrangeFree State, Bloemfontein.

FamennianFragments and whole specimens of small

Biogeography of South African Devonian fish 163

Taxa Localities

Table 1 Localities of Givetian-age fishes in SouthAfrica. Chondrichthyan higher taxa uncertain.Abbreviations for fossil fish localities: BH =Baviaanshoek; GR = Grootrivier; HS =Hondewater Stasie; LF = Leeubosfontein; LH

Leeuwenhoek; PH = Plathuis; TB DeDooms Tafelberg; VK = Vaalbokskloof; WBWarmwaterberg.

coelacanths thought to be juveniles (up to 47 mmlong) of a form close to the Frasnian to Visean genusDiplocercides are known from the WitpoortFormation (Anderson et al. 1994, figure 15; Gess andHiller 1995, figures 59-60). Five species were placedin Diplocercides by Cloutier and Forey (1991), onlyone of which is known from Gondwana (Iran) inFrasnian marine strata Oanvier 1974).

A second sarcopterygian from the WitpoortFormation is a large (ca. 2 m), incompletetristichopterid (Gess and Hiller 1995, figures 61-(3).With characteristic ulnare, subopercle, lower jawand cleithrum, this form is close to the cosmopolitangenus Ellsthenodon, members of which occur in bothmarine and freshwater deposits (P.E. Ahlbergpersonal communication).

A third sarcopterygian is represented in theWitpoort Formation by a single parasphenoid(Anderson et al. 1994, figure 14). It is possiblycongeneric with the lungfish Andreyevichthysoriginally described from the FamennianAndreyevka site, Tula Region, Russia (Krupina1987; Lebedev 1992). A Famennian site insoutheastern Turkey, with ostracods, anonychodont and the lungfish Chirodipterus, has alsoproduced remains of an Andreyevichthys-like form(Lelievre et al. 1993).

CHONDRICHTHYESAntarctilamna sp.Aztecodlls sp.Portalod!ls sp.

PLACODERMIPhlyctaenioidei

Groenlandaspis theroniGroenlandaspis sp. indet.

Phlyctaeniidae, gen. indet.Holonema-like arthrodire

Indeterminate arthrodires

ACANTHODIIClimatiiformes

Gyracanthides sp. cf. G. warreniIndeterminate acanthodian

OSTEICHTHYESOnychodontiformes

Onychodlls sp.

BH, GR, TB, WBGRGR

WB,HSGR, LH, TB, VK, WBWBGRGR, LF, LH, TB

GR, HS, PH, TB, WBHS, LH, WB

WB

Other GroupsA few, isolated, rhomboidal scale impressions

with poor mineralization and ornament detail, andisolated fin rays of an unknown palaeoniscoid arepresent on some of the large shale slabs from theWitpoort Formation. No ray-finned fish remains arecurrently known from the Middle Devonian sites.

SOUTH AFRICAN DEVONIANENVIRONMENTS

The Grahamstown Witpoort Formation exhibitsits estuarine character in a particular assemblage ofmarine, freshwater and terrestrial organisms (Gessand Hiller 1995; Long et al. 1997). A marineinfluence at the site is indicated by the presence ofthe ptyctodont placoderm, the Diplocercides-likecoelacanth, brown algae, eurypterids and brackish­water charophytes. No information can be gleanedfrom the presence of Groenlandaspis, Bothriolepis, thetristichopterid crossopterygian or ostracods, anyone of which may have been marine or freshwater.However, large arthrodires and lungfishes (one inthe Witpoort fauna) together are far more abundantin Gondwanan marine facies than in marginalhabitats (Lelievre et al. 1993). The riverine input tothe system is indicated by the presence of thegyracanthid, conchostracans (clam shrimps) andpalaeoniscoid fishes. Various debris from largelycopsids (Leptophloem australe) and theprogymnosperm ArcJzaeopteris sp. are found in the

shale and lag conglomerates of the site, possibly aswash-in material from flooding events.

Similarly, areas where fishes have been collectedin the lower KIipbokkop Formation may represent aformer brackish bay or delta platform system (Longet al. in press). Areas of possible marine influenceon brackish systems may be reflected where theholonematid and the Onychodlls were found (Table1). No definitive marine character exists for theAdolphspoort Formation, whereas thin trace fossilsoccur in the lower KIipbokkop Formation.

A non-marine, brackish to freshwater depositionalsetting is indicated for the upper Bokkeveld Groupfish-bearing horizons by the absence of stenohalinemarine fauna, the presence of thin-shelled unionidbivalves and pockets of terrigenous vascular plants,and the low-diversity trace fossil assemblages (Longet al. in press). These authors discussed how theprevalence of the burrow taxon Spirophyton and thegeology of the Klipbokkop Formation favoured adelta-top environment with restricted, brackish tofluctuating salinities. Disarticulated fish remainsoccur scattered within dark grey to reddishbioturbated mud rocks or concentrated in thinconglomerates of strongly ferruginized mudflakes.The latter may be lags deposited within shallowdistributary channels on the delta platform.

In contrast to contemporary fish-bearing alluvialredbeds of the Aztec Siltstone, Antarctica, there isno evidence for subaerial exposure of the upper

164 M.E. Anderson, J.A. Long, F.J. Evans, J.E. Almond, J.N. Theron, P.A. Bender

Bokkeveld succession in the form of mudcracks orpedogenic calcretes. Although the palaeo­geographical position and age of the upperBokkeveld and Aztec Siltstone are similar, theycontrast strongly in their sedimentological facies.The Aztec Siltstone is characterized by fluvial andlacustrine sediments, with pedogenic calcretes andred beds (McPherson 1978; McLoughlin and Long1994), whereas the fish-bearing upper Bokkeveld isinterpreted as a brackish delta platform successionwith no evidence for subaerial exposure or seasonalaridity (Long et al. in press).

BIOGEOGRAPHIC AFFINITIES

Recent reconstructions of the Devonian worldhave produced two competing hypotheses oncontinental palaeogeography and the ocean basins,summarized in Young (1993a). Maps based onpalaeomagnetic data show the northern landmasses in close contact with Gondwana in the EarlyDevonian, and separated by a wide equatorialocean by Late Devonian times (Scotese 1986; Li et al.1993). In contrast, a palaeoclimatic and oceaniccirculation model, and most vertebratebiogeography, suggests the opposite: a LateDevonian ocean closure coupled with globalcooling. This palaeogeographic change also bestexplains the major Frasnian-Famennian extinctions(Copper 1986; Young 1990, 1993a). These authorsalso summarized the well-documentedbiogeographic trend in continental faunas that ledfrom provincialism in the Early Devonian to

cosmopolitanism by the Late Devonian ­qualitative evidence that supports the LateDevonian sea-closure hypothesis, as dopalaeoclimatic data (Scotese and McKerrow 1990;Scotese and Barrett 1990) and some otherpalaeomagnetic data (Bachtadse and Briden 1990).

Although both schools of thought have criticizedeach other (Li et al. 1993; Young 1989, 1993a), mostof the palaeogeographic reconstructions place whatwould become southern Africa in Gondwana athigh palaeolatitudes in the Middle/Late Devonian,with the southern margin lying at about 75°S.(Figure 8; Li et al. 1993; Scotese and Barrett 1990;Scotese and McKerrow 1990; Young 1989).Although Scotese and coauthors described thegeneral climate of West Gondwana then as "warm",a relatively cooler climate can be assumed for life at75°S. This would be especially true if Copper's(1986) global cooling model is considered, and isreinforced by good evidence for Late Devonianglaciation in the southern hemisphere (Caputo andCrowell1985; Veevers and Powell1987). However,McGhee (1989), although considering lethaltemperature decline the main cause of the Frasnian­Famennian extinction event, convincingly arguedthat glaciation in Gondwana probably occurrednearer the Famennian-earboniferous boundary.

The term Malvinokaffric Province has beenapplied to the South African invertebrate faunas ofEarly-Middle Devonian age, based largely onendemic species of brachiopods, trilobites,pelecypod and coral faunas which also occur inWestern Antarctica and South America. Young

S.A.

Figure 8 The landmasses of the Late Devonian (Famennian). Redrawn after Scotese and McKerrow (1990).

Biogeography of South African Devonian fish 165

(1987a, 1987b) suggested that the presence ofacanthodians like Machaeracanthus andchondrichthyans were possibly the vertebratefaunal expression of this province. The presence ofMachaeracanthus in the Ellsworth Mountains andOhio Ranges of Antarctica (Early Devonian; Young1986) shows the possible extension of this fauna intoEast Gondwana, although this assemblage wasrapidly displaced by the Middle Devonian AztecSiltstone fauna, of clear East Gondwanan affinity.The fishes of the Bokkeveld Formation could thusbe said to be the vertebrate expression of theMalvinokaffric Province in their highly unusualfaunal composition.

Schultze and Cloutier (1996) compared 40ichthyofaunas worldwide from the Middle/LateDevonian transition. Using UPGMA taxicclustering, similarities were analysed at generic andfamilial levels and plotted on a Devonian worldmap (Schultze and Cloutier 1996, figure 1). As theircomparative study centred on the Euramerican(Quebec) Escuminac Formation fauna, sites inGondwana seem to have been considered lessrelevant and only four faunas of Givetian-Frasnianage, all dominated by placoderms, were included.All four Gondwana pie diagrams are refigured hereand compared to the South African Givetian andFamennian faunas in Figure 9. Left out of Schultzeand Cloutier's figure 1 were several EastGondwanan (Victoria and New South Wales,Australia) non-marine assemblages of appropriateage, dominated by bothriolepidoids, Groenlandaspisand phyllolepids, with acanthodians andsarcopterygians subordinate. None of these faunas

contains chondrichthyans or agnathans (Young1993b).

The higher-level taxonomic composition of theSouth African Givetian fauna does not comparewell with any Middle/Late Devonian Gondwananichthyofaunas reported by Schultze and Cloutier(1996) (Figure 9). The Late Devonian marine Iranianfaunas lack gyracanthid acanthodians,Groenlandaspis (although see Lelievre et al. 1993:163) and the Gondwanan sharks shared by SouthAfrica and Antarctica (see above). Antarctilamnaand Gyracanthides occur in the older Emsian Khush­Yeilagh Formation of Iran (J.A. Long and P. Janvier,unpublished observations). Similarly, thefreshwater Mount Howitt (Frasnian) fauna alsolacks gyracanthids, phlyctaeniid and holonematidplacoderms, Gondwanan sharks and Onychodus, buthas its own Groenlandaspis species. In addition, theMount Howitt fauna is characterized by thepresence of three species of Bothriolepis andendemic, East Gondwanan phyllolepids,acanthodians, actinopterygians and dipnoans(Young 1993b). The fully marine Lower Frasnianfaunas of Western Australia (the Gneudna, Gogoand Sadler Formations) do not compare with SouthAfrica's Middle-Late Devonian faunas, beingdominated by tropical placoderms and lackingchondrichthyans, gyracanthids, groenlandaspidids(except for one occurrence in the GneudnaFormation) and phlyctaeniids. The marine Holonemaand Onychodus, however, are shared. The highertaxonomic composition of the Givetian AztecSiltstone also does not compare well with that ofSouth Africa (Figure 9), being greatly dominated by

MT HOWITT

(FRASNIAN)

IRAN

(FRASNIAN); ACANTHODIANS

~ ELASMOBRANCHS

II1II PLACODERMS

o ACTINOPTERYGIANSANTARCTICA

(GIVETIAN)

GOGO

(FRASNIAN)

S.A. BOKKEVELD(GIVETIAN)

S.A. WITTEBERG

(FAMENNIAN)

Figure 9 Taxonomic comparison, based on total numbers of species present, of four Gondwanan Middle/LateDevonian ichthyofaunas with the South African Givetian and Famennian faunas. Modified from Schultzeand Cloutier (1996).

166 M.E. Anderson, J.A. Long, EJ. Evans, J.E. Almond, J.N. Theron, P.A. Bender

antiarchs (Young 1988,1989; Long and Young 1995),yet the similarities at lower taxonomic levels arestriking. Both faunas share the presence ofGyracanthides, possibly the same species, G. warreni,the family Phlyctaeniidae as a relict late-survivinggroup, and three early xenacanth-like sharks (seeabove; also see Hampe and Long this volume). Twoof these sharks, Aztecodus and Portalodus, occurnowhere else but South Africa and the AztecSiltstone. The lacustrine/riverine Aztec lacks aholonematid and Onychodus, but has a largeGroenlandaspis (G. antarctica) that may have closeaffinity with G. theroni (Long et al. in press).

We believe that the South African Givetianhorizons are probably not well collected and will infuture probably yield more major fish taxa,currently absent due to inadequate sampling.Although composed of only 9-10 taxa, the SouthAfrican Givetian fish fauna is also notable for itslack of thelodonts, antiarchs, and majorcrossopterygian families. With its relatively higherproportion of congeneric elasmobranchs, the SouthAfrican Givetian fauna is more similar to that ofAntarctica than it is to other Gondwana sites.Lelievre et al. (1993) considered that a fauna with ahigh shark and acanthodian diversity but fewplacoderms suggested cool climates. However, themid-latitude Aztec fauna has placoderms formingnearly half its diversity (Long and Young 1995).Although characterized by such freshwater taxa asGyracanthides and xenacanth-like sharks, othermembers of the South African fauna are consideredmarine (Onychodus sp., the holonematid). Stillothers give no information on the possible degree ofmarine influence; the phlyctaeniid andGroenlandaspis theroni may have been marine orfreshwater. If the present proportional make-upstands the rigours of testing, we believe theGivetian ichthyofauna of South Africa was a high­latitude, endemic assemblage (at low taxonomiclevels) that evaded many of the cosmopolitantrends underway elsewhere. Southern Gondwana(South Africa and Antarctica) may have been thelast refuge of the Phlyctaeniidae. However, detailedanalysis of the palaeogeographic relationships ofSouth African and East Gondwana ichthyofaunasawait further systematic study of Australian andAntarctic material. It remains unclear whether theprobable high palaeolatitudinal position of theupper Bokkeveld succession or its inferredrestricted (brackish) habitats made the greatercontribution to the ichthyofaunal impoverishment.

The higher-level taxonomic composition of theSouth African' Famennian Witpoort ichthyofaunacompares well with that of the Iranian (Kerman)fauna, and, to a lesser extent, that of Mount Howitt(Figure 9). Both of these are very different fromSouth Africa at lower taxonomic levels (Lelievre etal. 1993; Young 1993b). The Witpoort fauna does

not compare well with faunas from similarFamennian Euramerican habitats recentlydescribed. The brackish Andreyevka Basin, Russia,is dominated by sarcopterygians and has only oneplacoderm and no acanthodians or actinopterygians(Lebedev 1992). The Andreyevka Basin was subjectto rapid fluctuations in salinity, thus being ratherunsuitable for lacustrine acanthodians andactinopterygians.

The Famennian Baltic brackish seas also do notcompare favourably with the Witpoort fauna. Fromfour sites in Latvia, Luksevics (1992) detailed astrong dominance of predatory sarcopterygianscoupled with a low diversity of antiarchs. Othermembers of the fauna are typical Euramericanacanthodians, the arthrodire Dunkelosteus and anagnathan, Psammosteus.

In East Gondwana (New South Wales, Australia),three low latitude freshwater Famennian faunas alsodo not compare closely with the Witpoort fauna(Young 1993b, 1995). All are Groenlandaspis-Bothriolepisfaunas as well, but also contain the antiarchRemigolepis. The Jemalong-Canowindra fauna also hasphyllolepids and a holoptychiid, both absent from theWitpoort fauna. The Worange Point fauna is similar tothe Jemalong-Canowindra fauna, but lacksphyllolepids. The Grenfell fauna is most similar to theWorange Point fauna, sharing a species ofGroenlandaspis, having a holoptychiid and also lackingphyllolepids. However, it contains a sinolepidantiarch, an Early-Middle Devonian relict group byFamennian times, entirely lacking in West Gondwana.

Similarities between the Witpoort fauna and EastGondwana are evident in the presence of a largeGroenlandaspis and a Bothriolepis with affinities tothe Aztec Silts tone fauna, and a Gyracanthidesspecies with affinity to the later (Tournaisian) G.murrayi from Victoria, Australia (Long et al. 1997).Also, the Famennian Canowindra fauna of NewSouth Wales has a tristichopterid present which issuggested to be a sister taxon to Eusthenodon(Johanson and Ahlberg 1997), the latter genus isalso thought to occur in the Witpoort fauna. Noichthyofauna has so far been found in the SouthAmerican Famennian. To date only isolatedactinopterygian scales have been reported fromBolivia (Janvier and Suarez-Riglos 1986).

ACKNOWLEDGEMENTS

We are grateful for the hospitality and fieldlogistics abundantly supplied by the De Vriesfamily of Warmwaterberg, Roy and LucyOosthuizen of Zwartskraal, and Andre and JeanMarais of Grootrivierhoogte during our 1996expedition. Generous financial assistance for thisand John Long's stay was provided by the AlbanyMuseum, Grahamstown, the J.L.B. Smith Instituteof Ichthyology, Grahamstown, the Bernard P. Price

Biogeography of South African Devonian fish

Institute for Palaeontological Research,Johannesburg, the Council for Ceoscience, Bellvilleand the Foundation for Research Development,Pretoria. Specimens were examined and donationsreceived from the collections of J.c. Loock,Univeristy of the Orange Free State and O.A.Theron of the farm Soetendals Vlei. Drawings andmaps were rendered by Ray Vogel (Figures 1, 8, 9)and Elaine Heemstra (Figures 3, 6), J.LB. SmithInstitute. For loans of specimens and curation needswe thank the staffs of the Albany Museum, theSouth African Museum, the Montagu Museum andthe Bernard P. Price Institute.

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Manuscript received 30 January 1998; accepted 13 November1998.