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Quaternary International 255 (2012) 158e170

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Quaternary International

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A reappraisal of the dwarfed mammoth Mammuthus lamarmorai (Major, 1883)from Gonnesa (south-western Sardinia, Italy)

M.R. Palombo a,*, M.P. Ferretti b, G.L. Pillola c, L. Chiappini d

aDipartimento di Scienze della Terra, Università di Roma “La Sapienza”, CNR, Istituto di Geologia Ambientale e Geoingegneria. Piazzale A. Moro, 5 - 00185 Roma, ItalybDipartimento di Scienze della Terra, Università degli Studi di Firenze, via G. La Pira 4, 50121 Firenze, ItalycDipartimento di Scienze della Terra, Università degli Studi di Cagliari, via Trentino 51, 09127 Cagliari, ItalydMuseo di Storia Naturale e del Territorio dell’Università di Pisa, Pisa, Italy

a r t i c l e i n f o

Article history:Available online 13 June 2011

* Corresponding author.E-mail address: mariarita.palombo@uniroma1.it (M

1040-6182/$ e see front matter � 2011 Elsevier Ltd adoi:10.1016/j.quaint.2011.05.037

a b s t r a c t

The Gonnesa Quaternary deposits have been cited since the end of the 19th century due to the discovery,during the construction of a railway, of an incomplete postcranial skeleton belonging to an endemicdwarfed elephant, afterward described by Major as a new species (“Elephas lamarmorae” Major, 1883).Although the remains have since been reported in the literature as coming from the aeolian depositsoutcropping at Funtana Morimenta, the precise provenance of the findings and their chronostrati-graphical setting remained uncertain. Taking into account the route of the now disused railway, thestratigraphical successions of the Morimenta area, and the fact that the elephant bones were actuallycollected during a number of excavations spanning several decades, the location of the fossiliferous site ismost likely on the northeast end slope of Guardia Pisano hill (Gonnesa), where aeolianites correlate withthe Funtana Morimenta Formation (FMF) outcrop. The FMF is supposed to predate the onset of the MIS5e climatic event and the Tyrrhenian “Panchina” overlies equivalent deposits cropping out along theGonnesa Gulf coast. Therefore, the hypothesis that the elephant remains found in the “Morimenta” areawere retrieved from late Middle Pleistocene deposits cannot be ruled out. The anatomical features of thebones suggest they represent a single individual, perhaps partially exposed and damaged before thediscovery. New evidence, including a thus far unpublished tusk fragment from the Guardia Pisano hill(Gonnesa), whose Schreger angles fall within the range of Mammuthus, supports the systematic attri-bution of the incomplete Morimenta skeleton to a dwarfed mammoth. The size reduction of thisSardinian dwarfed mammoth is discussed in light of body-mass changes undergone by insular endemicelephants.

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1. Introduction area (Gonnesa, south-western Sardinia). On the basis of these

Proboscideans are known to have frequently colonized islands,giving rise to several endemic taxa with more or less reduced bodysize in comparison to their continental ancestors. In the Mediter-ranean region, palaeoloxodont endemic species were among themost characteristic and common taxa in Pleistocene endemicunbalanced or impoverishedmammal faunas from thewestern andeastern Mediterranean islands (e.g. Sicily, Malta and the AegeanIslands, Crete, the Cyclades, Dodecanese Islands and Cyprus), whilescanty remains of dwarfed Mammuthus species have only beenreported from Sardinia and Crete (Palombo, 2007; Ferretti, 2008and references in those papers).

In Sardinia, elephant postcranial remains were first reported atthe end of the 19th century by Acconci (1881) in the Morimenta

.R. Palombo).

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bones, Major (1883) described the new species “Elephas lamar-morae”, providing neither a diagnosis nor an illustration. Later,some isolated molars were discovered in post-Tyrrhenian (post-MIS 5e) breccias at Tramariglio (Alghero) (Malatesta, 1954;Palombo et al., 2008a), in a pre-Tyrrhenian pedogenized beachdeposit (?MIS 7 or older) cropping out at San Giovanni di Sinis(Oristano, western Sardinia) (Maxia and Pecorini, 1968; Ambrosetti,1972; Melis et al., 2001; Chesi et al., 2007; Lecca and Carboni, 2007),and in alluvial deposits (possibly late Middle Pleistocene in age)filling the Campu Giavesu Basin (Sassari, north-western Sardinia)(Palombo et al., 2005) (Fig. 1). The morphological and biometricalcharacteristics of these molars clearly indicate that they belong tothe genus Mammuthus. Accordingly, all the specimens found inSardinia have been ascribed to the species “Mammuthus lamar-morae” (Major, 1883) (recte Mammuthus lamarmorai according toICZN 1999). The species has been regarded as occurring in Sardiniaat the time of the Dragonara faunal subcomplex (Palombo, 2006,

Fig. 1. Geological map of Sardinia showing the localities where elephant remains have been discovered: 1) Tramariglio (Alghero): right ?M1 in occlusal view; 2) Campu Giavesu(Sassari): last right upper molar in occlusal view; 3) San Giovanni di Sinis (Oristano): right upper molar, in occlusal view; 4) Fontana Morinenta (Gonnesa): right pes in anterior view.

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2009a), during the lateMiddle and Late Pleistocene. However, thereare no firm stratigraphical constraints to infer the actual chrono-logical extent of the persistence of dwarfed mammoth populationson the island.

The aim of the present paper is to present an inventory of thefossil elephant remains from the “Morimenta” area, includinga description of the portion of a tusk (Fig. 2), originated from theeastern slope of the Guardia Pisano hill (Gonnesa), and to revise theknown information about their discovery in order to infer thepossible stratigraphical provenance of these bones and the rela-tionships with other rare Sardinian proboscidean findings.

A detailed anatomical study of the Funtana Morimenta skeletonwill be presented elsewhere.

Fig. 2. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardinia): large fvisible.

2. Historical background and geological setting

2.1. Historical background

The Gonnesa Quaternary deposits have been cited since the endof the 19th century when Lamarmora (1858) illustrated the sectioncropping out at the source, “Fontana Morimentu” (at presentspelled Funtana Morimenta), and made comparisons with similardeposits in Sardinia and around the Mediterranean Sea (Fig. 3).

The Funtana Morimenta area is well known to Sardinian geol-ogists due to the discovery of an incomplete skeleton reported byAcconci (1881). The bulk of these bones, found during theconstruction of a railway, directed by a German engineer, were sent

ragment of tusk, on the transversal sections (right) Schreger lines and angles are clearly

Fig. 3. The Fontana Morimenta section (middle) in the stratigraphical sketch by Lamarmora (1858) (left). On the right the label accompanying the Mammuthus lamarmorai remainskept in the Naturhistorisches Museum of Basel (Switzerland).

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to Pisa. Acconci (1881) reported the bones as having been found inthe “Marimenta” area, without providing a more precise location ofthe finding. In the author’s opinion, the bones belonged to an adultindividual, whose size differentiated it from any continentalelephant. The “Marimenta” elephant was, according to Acconci(1881), similar in size to those found in Malta by Spratt andknown at that time as “Elephas Melitensis” (sic) Falconer (seeAdams, 1874), albeit larger than some of the Maltese remains (e.g.a humerus) described by Busk (1867). Accordingly, Acconciconcluded that the “Marimenta” elephant represented a new,endemic dwarfed elephant.

In 1883, Major assigned the “Morimenta” skeleton to the newspecies “E. lamarmorae”. In his description of the species, Major(1883) only reported that it is similar in size to the Maltesespecies “Elephas mnaidriensis “ fromwhich the Sardinian one differsmarkedly in the morphology of the carpal and tarsal bones, whichresembled (except for size) that of the “Pliocene species Elephasmeridionalis” (Major, 1883). The English palaeontologist, however,provide neither a description nor any figures of these bones, toillustrate the supposed characteristic features of this species. In alllikelihood, Major visited the Funtana Morimenta area and collectedadditional fragmentary remains (ribs and vertebrae), now housedin the Naturhistorisches Museum of Basel (Switzerland) (ComaschiCaria,1965, p. 4, p. 4). A note associatedwith theMorimenta sampleat NHMB, possibly handwritten byMajor himself, indicates that theexcavation of the skeleton was initially made by the Germanengineer and later continued by Major (Fig. 3).

Part of the Morimenta skeleton was brought, likely by Majorhimself, to the Naturhistorisches Museum of Basel, whereas theremainder of thematerial was kept in the paleontological collectionof the University of Pisa (now Museo di Storia Naturale e del Ter-ritorio dell’Università di Pisa, MSNT; Chiappini, 2006). The lattermaterial was partially described by Vaufray (1929), who referredthe fossils to the Maltese species “Elephas melitensis” on the basis ofsize alone.

Further investigations were carried out during the officialmapping of the area (Novarese, 1914). Two molars, found at thesame site at the end of the 19th century and apparently bought bya German private collector, are nowmissing (Comaschi Caria, 1965,p. 4, p. 4).

Malatesta (1954), in a paper reporting new elephant dentalremains from Tramariglio (Alghero), discussed the elephant from“FontanaMarimenta” (sic), referring it to “E. lamarmorae”, thereforenot accepting Vaufrey’s (1929) attribution.

Comaschi Caria (1965) suggested, on the basis of notes associ-atedwith theMorimenta sample stored at NHMB, that the elephantremains might have been collected from the “Morimenta” area in

successive excavations, over more than forty years. The Sardinianpalaeontologist also reported a finding of a few elephant bonesfrom the nearby Cuccu de Cori (or de Gori) locality. Three unpub-lished thoracic vertebrae in anatomical connection, seemingly fromthe same skeleton, are stored in the Geological and PaleontologicalMuseum “Domenico Lovisato”of the Cagliari University (MDLCA;Italy) without indicating the collector or the time of discovery,while an incomplete tusk, discovered 25 years ago by GiuseppeLubelli and Ombretta Canalis at the Guardia Pisano hill, not far fromFuntana Morimenta (Fig. 5), is now displayed in the PASMuseum ofCarbonia (south-eastern Sardinia).

2.2. What about the actual location of the fossiliferous site?

TheMorimenta area takes its name from the Rio Morimenta andcommonly refers to the area included between the Guardia Manna,Cuccu de Gori, Serra Pirastu and Serra Nuraxi hills, located SSWfrom the center of Gonnesa (Fig. 5).

According to the several official maps, the name Funtana Mor-imenta (or similar spellings) does not appear, but the presence ofa source and related fountain installations for the capture anddistribution of water, clearly indicate that the entire name “FuntanaMorimenta” is restricted to the area very close to this fountain.Acconci (1881) and Major (1883) indicated a generic “Marimenta”or “Morimentu” area, while Lamarmora (1858), the foremostreference at that time, utilized the name “Fontana Morimentu”,illustrating the stratigraphical section located in correspondence tothe fountain (Fig. 2).

The problem arose when a more accurate study of this area(Palombo et al., 2008b) demonstrated that the old railway does notcross the area of Funtana Morimenta s.s. but flanks Cuccu de Goriand then directs toward the Bacu Abis Station, then turns andcrosses the Guardia Pisano slope, cutting, in several points, thePleistocene aeolianites (Fig. 5). The best exposed successions occuron both sides of the small bridge, especially in a recently exploitedsand quarry (Melis et al., 2002; Palombo et al., 2008b). The north-eastern slope of the Guardia Pisano hill is also the place wherea portion of a tusk has been found. In the authors’ opinion,Comaschi Caria (1965) used the name Cuccu de Gori (or de Cori) forindicating the location of some additional, unspecified findings,because it represents the closest available toponym for the aeo-lianites cropping out on the NE slope of the Guardia Pisano hill. Forthese reasons, the more probable site of the discovery of the M.lamarmorai remains could have been the uppermost portion of theaeolianite outcropping on the Guardia Pisano hill, where the routeof the disused railway is still visible in aerial images (Fig. 5).

Fig. 4. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardinia): largely incomplete thoracic vertebrae in lateral (a,b) dorsal (c), anterior (d) and posterior (e)views.

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2.3. Geological setting

During the Pleistocene, the western Sardinian coasts werestrongly affected by aeolian processes, generating a system of dunesand associated facies, extending several kilometers inland from thecoast. These aeolian deposits alternate with palaeosols and more orless marked erosional surfaces, associated with colluvial/alluvialand fluvial deposits (see inter alios Maxia and Pecorini, 1968; Orrùand Ulzega, 1986; Ulzega and Hearty, 1986; Andreucci et al., 2010;Pascucci et al., 2010 and references therein).

Orrù and Ulzega (1986) recognized several generations of dunesalong the coast: the oldest aeolian deposits (“Funtana MorimentaFormation”, FMF) were assigned to the Middle Pleistocene, and themost recent ones to a generic Upper Pleistocene. The localgeological context indicates that the FMF is older than MIS 5e, dueto the relationships observed at Funtanamare shoreline (Gonnesa)and outcroppings above the sea level in the Gonnesa Gulf where,along the Plage e Mesu beach, a Tyrrhenian conglomerate (MISsubstage5e) lies on the erosional surface, cutting these aeolianites.The second aeolian complex, well-cemented and with crossbedding, cropping out into the valley of Riu Crabiola, has been

attributed to the post-Tyrrhenian (Orrù and Ulzega, 1986). The ageof the coastal aeolian deposits has recently been questioned and itis still matter of debate. This lends further uncertainty to the age ofthe M. lamarmorai from the “Morimenta” area that has beenthought to belong to the landward aeolianite equivalents.

The strong controversy among specialists about the SardinianQuaternary stratigraphy are mostly due to some inconsistencies inOptically Stimulated Luminescence (OSL) dates and to the scanti-ness of either reliable isotopic data or precise biostratigraphicconstraints of coastal deposits (see e.g. Andreucci et al., 2010;Catto, 2010; Coltorti et al., 2010; Thiel et al., 2010). The geolog-ical and stratigraphical settings of a number of sedimentarysuccessions along the western Sardinian coast show that aeoliandeposits occur both below and above Tyrrhenian deposits, rich inmollusc remains including Strombus bubonius (MIS 5e) (e.g.Pecorini, 1954; Carboni and Lecca, 1985; Ulzega and Hearty, 1986;Kindler et al., 1997; Andreucci et al., 2006, 2009, 2010; Lecca andCarboni, 2007; Pascucci et al., 2010). Although the recent OSL,14C, and sequence stratigraphy data concerning the Pleistocenecoastal deposits of western Sardinia triggered increasing debates,the palaeoenvironmental evolution of north-central coastal areas

Fig. 5. Map showing the localization of sites mentioned in the text.

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of western Sardinia could now be depicted more soundly. Asregards M. lamarmorai, for instance, at San Giovanni di Sinis(Fig. 5), where the most complete late Middle to Late Pleistocenesuccession outcroppings and many solid data are available (Leccaand Carboni, 2007; Andreucci et al., 2009), all data confirm thatthe age of the level yielding the molar of M. lamarmorai is pre-Tyrrhenian (MIS 6 or older) (Melis et al., 2001 and referencestherein; Chesi et al., 2007; Andreucci et al., 2009).

All in all, OSL dates, coupled with results obtained by sedi-mentological and stratigraphical analyses of several key strati-graphical sections, may suggest a correlation between the lowerportions of the so-called FMF and the pre-Tyrrhenian aeolian unitscropping out in the Sinis peninsula (central-western Sardinia) andin the Nurra area (north-western Sardinia), as well (Fig. 5).Preliminary OSL dating, carried out on the aeolianite depositsextensively exposed along the Porto Paglia cliff (Fig. 5), indicates anage older than 130 ka (Fanelli, 2011 personal communication to

G.L.P.), while six 14C analyses on Glycimeris shells, Praemegaceroscazioti teeth and charcoal found in the same deposits gave incon-sistent ages. At the Guardia Pisano hill, aeolian deposits wereexposed in the sedimentary sequences of a now worked-out cave.The nearly 20 m high stratigraphical section includes aeolian andalluvial deposits, arranged by Melis et al. (2002) into three units(Unit A,B, and C), whose age was inferred on the basis of the 14C age(43,000 � 1400 BP) obtained for charcoal remains found in thealluvial deposits of the second Unit B. In Unit A (?MIS 6 to MIS 5d),aeolian cross-bedded deposits (at the bottom) are overlain bya palaeosol, cut by an erosional surface, on which aeolian sandydeposits and red soil lie; Unit B, separated from Unit A by a deeperosional surface (?MIS 4), is made up of about 6 m of gravely,sandy and clayey alluvium, deposited by a braided stream system (?MIS 3); Unit C is made up of about 7e8 m of aeolian cross-beddeddeposits and by yellowish-red soil. At the top of the section, well-cemented aeolianites crop out, where the old railway is still

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visible. The 14C dating of the alluvial deposits, within the “FuntanaMorimenta” aeolianites at the Guardia Pisano sand quarry, and theresulting chronostratigraphical inferences, have to be consideredwith caution as the radio-carbon dating falls close to the lower limitof the radiocarbon dating method.

All in all, although there are no firm stratigraphical constraintsto infer the actual chronostratigraphical position of the mammothremains found in the “Morimenta” area, assuming that they wouldhave been retrieved from the landward aeolianite equivalent to theFMF outcropping at the Guardia Pisano hill, a late Middle Pleisto-cene age for the M. lamarmorai from “Funtana Morimenta” cannotbe completely ruled out.

3. Materials and methods

All of the available material of the Morimenta elephant stored atMSNT, NHMB and MDLCA has been directly studied and measured.Comparisons were made with the Puntali Cave samples of Palae-oloxodon “mnaidriensis” (Ferretti, 2008), Palaeoloxodon falconerifrom Spinagallo (Ambrosetti, 1968; Palombo unpublished data),Mammuthus meridionalis from Upper Valdarno (IGF sample), andPalaeoloxodon antiquus from various Italian sites (Ferretti, 2008).

The Schreger angles were observed and measured on thenatural, fractured, undercut transverse sections visible on the flatsurfaces of the distal and proximal broken portions of the tusk, thisdue to its preservation status not allowing the making of transversesections. Each surface was photographed in high-resolution, andthe images were processed with the software CV9000, whichallowed measurement of Schreger angles, with a precision of about95% (Palombo and Villa, 2001, 2007). The whole spectrum of theangles was measured, including ‘outer’ (near the dentine-cementum junction) and ‘inner’ angles (near the proximal-distaltusk axis).

4. Funtana Morimenta dwarfed elephant

4.1. The skeleton

Acconci (1881) briefly described the skeleton, listing thefollowing elements: a complete left tarsus, right distal carpals andmetacarpals, left tibia and fibula, a distal portion of the left femur,a left scapula articulated with a partial humerus, articulated rightradius and ulna, a complete right humerus, a portion of the rightscapula, a fragment of the pelvis and a fragment of a mandible.

As mentioned above, the manus and pes (Fig. 6), later describedby Comaschi Caria (1965), were brought to the NaturhistorischesMuseum of Basel (Switzerland; NHMB), while the remainder of the

Fig. 6. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardinia):manus (a) and pes (b) (Naturhistorisches Museum of Basel, Switzerland).

skeleton remained in Italy and is now kept at the MSNT (Chiappini,2006). It is worth noting that the sample kept at NHMB actuallyincludes several other skeletal elements not mentioned by Acconci(1881) nor by Major (1883): nine vertebrae, several ribs fragments,fragment of the right scapula, fragments of the pelvic bone, thediaphysis of the left humerus, left radius and ulna (fused), carpalsand metacarpals of the left manus. As already shown by ComaschiCaria (1965), notes accompanying the specimens suggest that thislatter material might have been collected from the same site afterthe first discovery of the partial skeleton, in a series of successiveexcavations from 1881 to 1923.

On the other hand, there are no traces of the tibia, the fibula andthe mandibular fragments mentioned by Acconci (1881), neither inPisa nor in Basel. It cannot be excluded that Acconci misidentifiedthis material.

The Morimenta elephant sample includes several articulatedelements: foot, left anterior limb (humerus, radius and ulna), rightanterior limb (scapula and humerus), and three undescribedthoracic vertebrae, stored in the MDLCA (Fig. 4). The association ofthese articulated skeletal portions is indicated by their relative sizeand stage of growth: the dimensions of paired bones (e.g. left andright scapulae, humeri, and metacarpals) are almost identical; allthe epiphyses of the long bones are fully fused. Moreover, there areno duplicate skeletal elements. The evidence thus supports thehypothesis that all of the elephant skeletal remains found at Fun-tana Morimenta pertain to a single, fully mature individual.

Most of the bones are fractured, but the preserved parts are notdeformed. In some cases, the fractures look rather recent, sug-gesting they were likely done during the excavation. On the otherhand, a fragment of the distal articular end of the right humerus iscemented to the ulna, indicating that the two bones were stillarticulated when found.

Fig. 7. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardinia):largely incomplete scapula; a fragment of the humerus caput is still articulated to theglenoid cavity.

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To sum up, re-examination of the Funtana Morimenta sampleskept at NHMB, MSNT and MDLCA, confirms that the preservedelements represent only postcranial bones and that they weresurely associated and, in some cases, even articulated: the axialskeleton is represented by 12 vertebrae, pertaining to the dorso-lumbar segment, and several rib fragments; the pectoral andpelvic girdles are represented by the two scapulae, of which theleft is the better preserved (Fig. 7), and of fragments of the pelvis,including a large portion of the right iliac wing; the appendicularskeleton consists of several elements of the right and left anteriorlimbs (stylopodium, zygopodium, basipodium and metapodium)and of the left posterior limb (stylopodium, basipodium, meta-podium), the right one being represented by only the fourthmetatarsal. Of the long bones, the right humerus is complete andnot deformed (Figs. 8 and 10), whichmakes it suitable for inferringthe size of the animal. Notably, both the right and left zygopodials(ulna and radius) are fused (Figs. 9 and 10). This feature, possiblyrepresenting a locomotory adaptation, occurs rather frequentlyamong small-sized insular elephant species, as Palaeoloxodon fal-coneri (Ambrosetti, 1968) and Palaeoloxodon mnaidriensis (Ferretti,2008) from Sicily, but not in Palaeoloxodon tiliensis, whose size isonly a bit larger than that of P. falconeri (Theodorou, 1983;Theodorou et al., 2007) and is rather rare among large-sizedcontinental taxa (Palombo et al., 2010).

As discussed below, the Morimenta elephant shows a differentdegree of size reduction from both Sicilian P. “mnaidriensis” andP. falconeri. The preliminary anatomical studies also point outdifferences in the morphology and proportion of the bonesbetween the Sardinian and Sicilian dwarf species. This is

Fig. 8. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardini

particularly evident in the humerus of M. lamarmorai, which ischaracterized by a relatively narrow proximal end, and by a muchless developed deltoid tuberosity, with respect to SicilianP. “mnaidriensis”. By contrast, the carpi of both of the insular formsare lower and wider than that of the congeneric mainland forms.Investigation is underway as to what extent the morphology ofM. lamarmorai bones was affected by the dwarfing process in orderto discriminate between the phylogenetic signal and functionaladaptations. Palombo et al. (2005) considered the morphology ofthe carpal and tarsal bones (Figs. 6 and 11) to be closer to Mam-muthus than to Palaeoloxodon. A preliminary metric analysis of thecarpal bones comparing M. lamarmorai to P. “mnaidriensis”,Palaeoloxodon antiquus, and M. meridionalis, gave contrastingresults. Fig. 12 shows a scatter plot of the relative breadth (B/D%)versus the relative height (D/H%) of the unciform of variousspecies. The M. meridionalis and P. antiquus unciform samples are,indeed, well-separated along both axes. P. antiquus possessesa comparatively wider unciform than M. meridionalis, as hadalready been concluded by Reggiani (2001). The unciforms ofSicilian P. “mnaidriensis” separates it from those of P. antiquus andare characterized by an even lower and wider shape. TheM. lamarmorai unciform has an intermediate position in the graph,between the P. antiquus and P. “mnaidriensis” clusters. It is notablethat its shape differs from that ofM. meridionalis in being relativelywider and lower, a difference that seems to parallel that separatingP. “mnaidriensis” from its putative ancestor P. antiquus. Thus, the“palaeoloxodon-like” morphology of M. lamarmorai unciformmight be due to a change in its proportions related to the dwarfingprocess.

a): right humerus in anterior (left), lateral (middle) and posterior (right) view.

Fig. 9. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardinia): incomplete right radius and ulna in lateral (left), anterior (middle), and medial (right) view.

Fig. 10. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardinia):articulated right humerus and radio-ulna in lateral view.

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4.2. Schreger lines

Of particular interest, from a taxonomical point of view, is thelarge fragment of a tusk found at the Guardia Pisano hill (maximumlength of fragment ¼ 118 mm; maximum diameter at the brokendistal surface¼ 29mm;maximumdiameter at the broken proximalsurface ¼ 35 mm; estimated maximum circumference at thebroken proximal surface ¼ 223 mm), likely a portion of the distalpart minus the tip. This is because the diameter of the pulpal cavityon the broken distal surface is less than 2mm, and the pulpal cavityis nearly obliterated.

The Schreger linepattern clearly indicates that the tuskbelongs toa Mammuthus representative (Fig. 2). It is well known that theSchreger pattern, a unique characteristic of proboscidean ivory andvisible in cross-sections of tusks (Obermayer, 1881), consists of twointersecting sets of spiral lines that radiate clockwise and counter-clockwise from the tusk’s longitudinal axis. The intersections ofSchreger lines form two types of Schreger angles - concave anglesopening towards the medial (inner) area of the tusk, and convexangles opening towards the lateral (outer) area of the tusk e whosewidth increases from the tusk nerve/pulp cavity (inner angles)towards the dentine-cementum junction (outer angles) (Espinozaand Mann, 1993; Fisher et al., 1998; Palombo and Villa, 2001;Trapani and Fisher, 2003). This pattern is the visual manifestationof the arrangement of the dentine tubules along the longitudinal axisof the tusk. Microlaminae are formed by laterally aligned dentinaltubules which change their orientation incrementally from onemicrolamina to the next in helicoids, a stack of dentinal tubules thatchange their orientation by 180� anticlockwise. Below thecementum, the soft derivative of the enamel layer, the structure ofthe dentine ismade up of nearly complete 180� helicoids. After Locke(2008), “the Schreger pattern in proboscidean ivory consists of thesehelicoids divided tangentially into columns in the length of the tusk”.

According to Fisher et al. (1998), the values of Schreger angles inMammuthus tusks range from 62� to 105�, with a mean of 87.1�. Thevalues of the ‘outer’ Schreger angles of Mamuthus primigenius,

Fig. 11. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardinia):uncinatum in anterior-dorsal view (a), magnum in anterior-dorsal view (b), calcaneumin anterior view (c), navicular in dorsal view (d), cuboid in dorsal view (e), ectocu-neiform in dorsal view (f).

Fig. 12. Scatter diagram of the relative breadth (GB/D%) and relative height (GB/H%) ofunciforms of Mammuthus lamarmorai from Gonnesa Basin and other Italian fossilelephant species. GB, greatest breadth. D, depth. H, height.

M.R. Palombo et al. / Quaternary International 255 (2012) 158e170166

measured by Trapani and Fisher (2003) at the dentine-cementumjunction, range from about 70� to100�, while single maximumvalues of 115� and 125� were found by Ábelova (2008) close to thedentine-cementum junction, around 0e2 cm from the tusk surface.In the sample of Mammuthus primigenius (49 tusks) examined byPalombo and Villa (2001, 2007), the values of Schreger outer anglesrange from 65� to 90� with a mean of 71.2�, while the values ofinner Schreger angles range from 33� to 55�, with a mean of 41�,showing an increase from the center of the tusk to the dentine-cementum junction of about 57%. Similar values characterize the‘outer’ Schreger angles of M. meridionalis (67�e85�) and Mammu-thus trogontherii (68�e77�) (Palombo and Villa, 2001, 2007). Inadult individuals of P. antiquus, the Schreger angles near thedentine-cement junction have a width ranging from 107� to135�,about 128% more than the width of the angles of the central zone(near the pulpal cavity) (Palombo and Villa, 2007). In Palaeoloxodonfalconeri the Schreger angles range from about 89 to 94� near thepulpal cavity, to 105e108� in the middle, to 130e134� near thedentine-cementum junction, matching the range shown by youngpalaeoloxodonts (Palombo, 2003).

On the natural, proximal cross-section of the tusk found at theGuardia Pisano hill, the values of the Schreger angles, including thosenear the dentine-cementum junction, are definitely less than 90�

(Fig. 13), as was reported for the inner Schreger angles ofM. primigenius,M.meridionalis, andM. trogontherii and are definitelynarrower than in extant elephants and fossil palaeoloxodonts (seee.g. Palombo and Villa, 2001, 2007 and references therein). The rangeof variability of convex Schreger angles increases from the center ofthe tusk to the dentine-cementum junctionwith their average valueshowing an increase of about 78.8%. The Schreger pattern of the M.lamarmorai tusk differs from themajority of adultMammuthus tusks

in the low values of the Schreger angles, the marked “V” shape ofconvex inner and outer angles, and because the Schreger lines showan almost constant bend radius, diverging slightly from the radius ofeven the section near the dentine-cementum junction as occurs inyoung individuals and in sections made at the tip of the tusks ofadults (PalomboandVilla, 2001; Ábelova, 2008). The incompletenessof the specimen found at Gardia Pisano does not permit a hypothesisas towhether the adult tusks ofM. lamarmoraimight showa juvenileSchreger pattern as was observed in P. falconeri from Spinagallo cave(Palombo, 2003).

4.3. Body size estimates

A number of physiological variables and ecologically significantcharacteristics of mammals correlate with body size (e.g. metabolicrates, growth and reproduction, population density, home range,life-history traits, body). Therefore, in recent years there has beengrowing interest in the paleobiological implications of body size inextant and fossil mammals. And so, estimation of the body-mass(the best proxy of body size) of the M. lamarmorai constitutes animportant basis for evaluating the evolution undergone by thisdwarfed species after its geographic and reproductive isolationfrom the continental ancestor. The body-mass of extant mammalsis roughly correlated with their bone and teeth dimensions, but,despite the number of different uni- and multi-variate regressionequations proposed for large and small mammals, it is not an easytask to accurately estimate the body-mass of extinct species (seee.g. Legendre, 1986; Damuth and MacFadden, 2000; Alberdi et al.,1995; Delson et al., 2000; Andersson, 2004; Christiansen, 2004;Mendoza, 2006).

The peculiar dental anatomy and replacement pattern of ele-phantids, as well as the negative allometric reduction of the skullsand teeth of dwarfed insular mammals (see e.g. Gould, 1975;Azzaroli, 1982) make it imperative to focus on long bone dimen-sions (Roth, 1990; Christiansen, 2004; Palombo and Giovinazzo,2005). Moreover, the limb bone dimensions of large mammalsappear to have a very good predictive consistency because theysupport the body weight in static and dynamics conditions. In

Fig. 13. Values of inner and outer Schreger angles visible on the natural transversal proximal section of the fragment of Mammuthus lamarmorai tusk found at Guardia Pisano(Gonnesa). D ¼ distance from the pulpal cavity; Number of measured angles.

M.R. Palombo et al. / Quaternary International 255 (2012) 158e170 167

dwarfed elephants, long bone dimensions (length and circumfer-ence of the humerus and femur) “consistently provided the bestmass estimated” (Roth, 1990, p.158, p.158). Maximum humerus andfemur length have been indicated as the best variables for esti-mating body-mass in elephants weighing less than 2000 kg (Roth,1990), while length and least circumferences of long bones havebeen recommended as the best parameters for the prediction ofbody-mass for extinct proboscideans (Christiansen, 2004).

On the other hand, the body size of elephants is strictly corre-lated to the shoulder height. Among extant elephants, for instance,there is a significant relationship between body-mass and shoulderheight at different stages of ontogenetical growth, albeit substantialphysical differences exist between the two extant species, makingthe body-mass of Elephas maximus at any given shoulder heightgreater than that of Loxodonta africana. After Roth (1990), “massestimates derived from shoulder height depend in part upon thebody condition and in part upon the species of elephants in themodel sample” (Roth, 1990, p. 167, p. 167). As regards dwarfedpalaeoloxodonts (e.g. P. falconeri and Palaeoloxodon “mnaidriensis”from Sicily), ad hoc regression equations of body-mass overshoulder height based on extant elephant individuals of differentages would be more accurate than those from humerus and femurdimensions (see Palombo and Giovinazzo, 2005 for a discussion;Ferretti, 2008). Then again, the limb bones of very reduced in sizeinsular elephants show different proportions compared with thoseof their continental ancestors (possibly in response to a differentanatomical structure necessitated by reduced body size, changing,in turn, the static and dynamic equilibrium), and estimates derivedfrom long bone circumferences could result in the overestimationof the actual body-mass of dwarfed elephants. Conversely, bonecircumferences provide accurate estimates for elephants larger

than 2500 kg (Roth, 1990), particularly because humerus and ulnaleast circumferences are among the best variables for the predic-tion of the body-mass of proboscideans (Christiansen, 2004). Thedifferences in the estimates derived from different measurementsgreatly depend on the number of individuals forming the modelsample as well as the variability shown by these individuals.

This, coupled with the fact that the humerus is the onlycomplete long bone found in the “Marimenta” area, would argue infavor of using the dimensions of the humerus for the prediction ofbody-mass of M. lamarmorai.

The average body-mass prediction estimated from the humeruslength of M. lamarmorai, using Roth’s (1990) and Christiansen’s(2004) equations, range from about 400 kg to about 700 kg,while based on the humerus least circumference, the estimate issignificantly higher using both Roth’s (about 1500 kg) and Chris-tiansen’s equations (about 1300 kg), as would be expected forspecimens smaller than 2000 kg.

The body-mass inferred for M. lamarmorai, albeit only indica-tive, is roughly consistent with the size reduction shown in longbones. Based on the Basel and Pisa material, the size of the FuntanaMorimenta mammoth is midway between the size of P. mnai-driensis and Palaeoloxodon falconeri from Sicily. For instance, thehumerus is roughly the same as the smallest Mammuthus exilis(Roth, 1990, 1993), and is about 20% smaller than the smallesthumerus P. “mnaidriensis” from Puntali cave (Carini, Palermo,north-western Sicily) (Ferretti, 2008), and 24% larger than thelargest humerus of P. falconeri from Spinagallo cave (Siracusa,south-eastern Sicily) (Ambrosetti, 1968) (Table 1).

Although the actual shoulder height of M. lamarmorai from“Morimenta” cannot be confidently calculated due to the incom-pleteness of the radius-ulna, a height of about 140 cm has been

Table 1Measurements (in mm) of the right humerus (MSNT I 14677) ofMammuthus lamarmorai (Major, 1883) from Funtana Morimenta (Gonnesa, Sardi-nia). Observed Ranges (OR) for some variables in Palaeoloxodon “mnaidriensis” fromGrotta Puntali (Sicily; data from Ferretti, 2008), P. falconeri from Spinagallo (Sicily;data from Ambrosetti, 1968) and Mammuthus exilis (Santa Rosa Island; data fromAgenbroad, 2000) are reported for comparison.

MSNTI 14677

OR inM. exilis

OR inP. “mnaidriensis”

OR inP. falconeri

1. Greatest lengthfrom caput

450 e 490e650 e

2. Greatest lengthof lateral part

460 466e656 570e680 238e344

3. Greatest depthof proximal end

103 e e 62e98

4. Smallest breadthof diaphysis

64 e 66e84 29e58

5. Smallest circumferenceof diaphysis

200 e e e

6. Length of epitroclearcrest

144 e 175e218 e

7. Depth of distal end 88 e e e

8. Breadth of distal end >123 e 128e161 84e132

M.R. Palombo et al. / Quaternary International 255 (2012) 158e170168

estimated in order to further compare the body size ofM. lamarmorai with that of continental mammoths. In particular,the size of M. lamarmorai from the “Morimenta” area is about 65%in height and 96-92% in body-mass with respect to the old M.meridionalis male from L’Aquila (Maccagno, 1962) (Early Pleisto-cene, MIS 37 or MIS 35, Magri et al., 2010), and about 70-65% inheight and 91-85% in body-mass with respect to the 41 year oldmale from West Runton (UK) (early Middle Pleistocene, c. 700 ka),whose shoulder height has been estimated at 3.9 m, and its body-mass at around 9000 kg (Lister and Stuart, 2010). The size ofM. lamarmorai falls within the range of the smallestM. exilis, whoseshoulder height ranges from 150 to180 cm, while the body-mass

Fig. 14. Mammuthus lamarmorai (Major, 1883) from Gonnesa Basin (Western Sardinia):distal portion of the left femur in anterior (left) and posterior (right) view.

(estimated by the length of the humerus) ranges from about 350to more than 2000 kg. Finally, M. lamarmorai would have beenabout 64% in height with respect to the Holocene Mammuthusprimigenius from Wrangel Island (average estimated height ofabout 220 cm) (Siberian Arctic Ocean, Tikhonov et al., 2003), andabout 77% with respect to the shoulder height of an adult femalefrom Kolyma River (Yakutia, Eastern Siberia, Late Pleistocene, 48ka), which seems to have been among the smallest of the woolymammoths known thus far (Boeskorov and Mol, 2004).

5. Discussion and conclusion

The preliminary analysis of the elephants remains found in theGonnesa basin supports the hypothesis that only Mammuthusrepresentatives were present in Sardinia during the lateMiddle andearly Late Pleistocene and gives some additional information on theevolutionary process undergone by mammoth populations on theisland. As has been already suggested by previous authors(Palombo, 2007 and references therein), the colonization of theisland by mammoths was accomplished by mainland mammothsswimming to Sardinia, likely when marked climate oscillations,sustained by a periodicity of 100e125 ka, led to pronounced sealevel reduction, lessening the distance between the Corso-Sardinian massif and the continental coast. In Sardinia, elephantremains have, thus far, not been reported in the local faunalassemblages (LFAs) of the Orosei 2 faunal subcomplex, whereCynotherium sp. is recorded together with the archaic voleMicrotus(Tyrrhenicola) sondaari, and in the oldest LFAs of Dragonara sub-complex, where an archaic endemic deer, Praemegaceros sardusdated approximately at 450 ka, is also recorded (Van der Made andPalombo, 2006; Palombo, 2006, 2009a). In the “Morimenta” area,conversely, elephant fossils were found in aeolianite deposits thatprovided the remains of the derived species P. cazioti (Melis et al.,2002; Fanelli et al., 2008; Palombo et al., 2008b), as well as deerfootprints (Fanelli et al., 2007 and unpublished data).

Present stratigraphical evidence thus would suggest that theancestor of M. lamarmorai reached Sardinia in the late MiddlePleistocene, after 450 ka. At that time, western continental Europewas inhabited by only one mammoth species, M. trogontherii,which is thus to be considered as the most likely forerunner of theSardinian dwarf mammoth.

On the basis of body size estimates obtained for the skeleton,M. lamarmorai from the “Morimenta” area would have reduced itsheight at the shoulder by more than 2/3 with respect to both M.meridionalis and M. trogontherii. Available data, thus far, do notprove the claim that in the Sardinian dwarfed mammoth, as inother endemic proboscideans, smaller size and reduced weight ledto a reduction in graviportal posture and that limb bones becamemore slender with articular joints, bringing the limbs closer to thesagittal plane, allowing a more agile gait and a more secure loco-motion on relatively uneven ground than their mainland ancestors(Palombo, 2003 and references therein). In M. exilis from theChannel Islands, for instance, the femora were significantly longerthan in mainland mammoths and the position of the center ofgravity revealed that the endemic dwarfedmammoths were able tonegotiate slopes of as much as 10� steeper than Mammuthuscolumbi could do (Agenbroad et al., 1999; Agenbroad, 2001).Unfortunately, the femur of M. lamarmorai from “Morimenta” islargely incomplete (Fig. 14).

Ongoing researchwill hopefully shed some light on the extent ofthe morphofunctional modifications caused by the evolutionaryprocess of insularity in Sardinian mammoths.

In the past few decades, several authors have emphasized theroles played by different factors in explaining evolutionary patternsin isolated areas, especially changes in body size. Even recent

M.R. Palombo et al. / Quaternary International 255 (2012) 158e170 169

overviews have presented conflicting points of view, confirming orrejecting the soundness of the “rule”. Some authors maintain that itis a quite general principle (e.g. Lomolino et al., 2006; Köler et al.,2008; Palombo, 2009b; Welch, 2009; Benton et al., 2010 andreferences in those papers), others reject the generality of the“rule”, saying it would be an artifact of comparing distantly relatedgroups, showing clade-specific responses to insularity (Meiri et al.,2008). The body size of insular mammals results from a combina-tion of biotic and abiotic factors (geographic, climatic and ecologicalcharacteristics of the islands, structure of insular communities,biology of the species in question), whose importance could vary onspatial and temporal scales, giving rise to a different body sizeevolution even in species originating from the same ancestor (e.g.the dwarfed straight-tusked elephants from the Mediterraneanislands, Palombo, 2007, 2009b). As regards Mammuthus lamar-morai, the coeval, impoverished and strongly endemic faunaincludes, together with some small mammals (“Nesiotites” similis,Microtus (Tyrrhenicola) henseli, Rhagamys orthodon, Prolagus sar-dus), endemic otters (Magalenhydris barbaricina, Sardolutra ichnu-sae, Algarolutra majori), the mustelid Enhydrictis galictoides),a dwarfed, mixed-feeder megacerine (P. cazioti) (Palombo, 2005),and the small predator Cynotherium sardous, able to feed on smallprey such as Prolagus, andmaybe P. cazioti calves (Lyras and van derGeer, 2006; Novelli and Palombo, 2007). Although M. lamarmoraidid not suffer the predation pressure of any carnivore, the presenceof a medium sized herbivore might have prevented dwarfism fromreaching a major degree (cf. Palombo, 2007, 2009b).

Moreover, the scantiness of Sardinian mammoth remains aswell as the dimensional variability inferred by tooth dimensionposes intriguing, as yet unanswered questions. Given that all of theelephant remains found in Sardinia can be assertively ascribed toMammuthus, thatM. lamarmoraiwas described inmaterial from the“Morimenta” area, and considering the dimensional variability ofteeth from other localities, the questions are: was there only onemammoth species that inhabited Sardinia and dimensional scalingcould be regarded as progressive dwarfing anagenetic evolution, ordid mainland Mammuthus colonize the island more than one time,giving rise to either genetic introgression or to the origin ofdifferent species?

Available data, thus far, makes it difficult to confidently depict thescenario of the evolution of M. lamarmorai. Although a greatmorphological and sometimes dimensional variability seems to havecharacterized dwarfed elephants, presumably as a consequence, atleast in part, of an increase inmorphological and dimensional sexualdimorphism (e.g. Theodorou, 1983; Lister, 1996; Roth, 1993, 2001,Poulakakis et al., 2002; Palombo, 2007 and references therein;Ferretti, 2008), the M3 from Giavesu show features (enamel thick-ness, hypsodonty index, lamellar frequency and loop morphology)apparently more archaic and definitely larger than the specimenfrom San Giovanni in Sinis (Melis et al., 2001; Palombo et al., 2005and references in those papers). Accordingly the hypothesis thatmainland elephants had reached Sardinia during more than onemigratory wave, as already stated for Santarosae (Agenbroad et al.,1999) as well as Sicily (Palombo, 2007 and references therein) andCrete (Poulakakis et al., 2002) cannot be completely ruled out.

A systematic review of and a substantial increase in strati-graphical and biochronological data are needed to better understandthe evolutionary dynamics of elephant populations in Sardinia.

Acknowledgments

We are grateful to the directors and curators of all the Museumswhere the remains of M. lamarmorai from the Gonnesa Basin arestored. Francesco Landucci (Earth Science Department of theUniversity of Florence) restored and prepared the fossil specimens

stored at MSNT in collaboration with LC. We thank Lorenzo Rook(Florence) for his help and discussion. The English version of themanuscript has been revised by Dr. Steven Haire. This work wassupported by the project MIUR PRIN 2008RTCZJH_002 (Unit 2,Resp., M.R. Palombo).

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