Nouvelles interprétationsdes restes d'Équidés (Mammalia,Perissodactyla) de Nihowan (Pléistocène inférieur de la Chine du Nord): Equus teilhardi nov. sp.

The fauna yielded by the Nihowan lower pleistocene lacustrine deposits includes two species of Equus beside one Hipparion. Equus sanmeniensis was described in 1930 by Teilhard de Chardin and Piveteau; this species is characterized by its large size and the presence of cups on all incisors. Equus teilhardi nov. sp. is smaller and its lower incisors are devoid of cups. It is the first time that such an absence is noted among eurasiatic Equus; till now only some californian, south-american and african species were known to have lowers incisors without cups. The finding of several Equids in the same deposits and the significance of the lack of cups are briefly discussed.     

Chromosomal Assignment of Six Genes (EIF4G3, HSP90, RBBP6, IL8, TERT,and TERC) in Four Species of the Genus Equus

We mapped six genes (EIF4G3, HSP90, RBBP6, IL8, TERT, and TERC) on the chromosomes of Equus caballus, Equus asinus, Equus grevyi, and Equus burchelli by fluorescence in situ hybridization. Our results add six type I markers to the cytogenetic map of these species and provide new information on the comparative genomics of the genus Equus.     

The Villafranchian perissodactyls of Italy: knowledge of the fossil record and future research perspectives

The Villafranchian fossil record of Perissodactyla is of a great interest because the appearance of the genus Equus and disappearance of the genus Tapirus mark important faunal turnovers. Here, we provide new data on Italian Villafranchian Tapiridae, Rhinocerotidae, and Equidae with updates from the last comprehensive review; most relevant are those of the Rhinocerotidae and Equidae. At present only two Villafranchian rhinoceros’ species are documented in Italy: Stephanorhinus jeanvireti and Stephanorhinus etruscus. The two species can be distinguished by several morphological features and by the dimensions of their bones. Stephanorhinus etruscus occurred throughout the Villafranchian; despite the numerous records, its remains are not enough to investigate morphometric trends. The Equidae include seven species including new occurrences of Hipparionine horses and of the genus Equus. The statistical analyses performed on the Equus species show two different evolutionary trends, namely the stenonine lineage “Equus livenzovensis - Equus stenonis” and the small-to-medium-sized lineage “Equus senenzensis - Equus stehlini”, suggesting a different evolution of these species. Moreover, the analyses show close relationships between the Italian Equus stenonis samples and three European Equus stenonis subspecies (E. stenonis vireti, E. stenonis guthi, and E. stenonis pueblensis). We begin to reconsider the validity of E. stenonis subspecies identification in order to provide new perspectives on the taxonomy of this species.     

Cranial morphology and dietary habits of rodents

Rodents are important components of nearly every terrestrial ecosystem and display considerable ecological diversity. Nevertheless, a lack of data on the ecomorphology of rodents has led to them being largely overlooked in palaeoecological reconstructions. Here, geometric and linear morphometrics are used to examine how cranial and dental shapes reflect the diets of living rodent species. Although most rodents are omnivores or generalist herbivores, some species have evolved highly specialized carnivorous, insectivorous, and herbivorous diets. Results show that living rodents with similar diets display convergent morphology, despite their independent evolutionary histories. Carnivores have relatively elongate incisors, elongate and narrow incisor blades, orthodont incisor angles, reduced cheek tooth areas, and enlarged temporal fossae. Insectivores display relatively degenerate dentition, elongate rostra, narrow and thin zygomatic arches, and smaller temporal fossae. Herbivores are characterized by relatively broader incisor blades, longer molar tooth rows, larger cheek tooth areas, wider skull and rostrum, thicker and broader zygomatic arches, and larger temporal fossae. These results suggest that cranial and dental morphology can be used to accurately infer extinct rodent diets regardless of ancestry. Application to extinct beavers suggests that most had highly specialized herbivorous diets.     

Enamel Structure of Cuvieronius hyodon (Proboscidea, Gomphotheriidae) with a Discussion on Enamel Evolution in Elephantoids

Dental material of the South American elephantoid Cuvieronius hyodon from the Late Pleistocene of the Tarija Basin, Bolivia was sampled for a comprehensive analysis of the microstructure of the enamel. To examine variability at the dentition level, enamel samples of the upper incisor, second deciduous premolar, and molars were sectioned. The incisor and cheek teeth enamel is compared to that of other proboscideans in order to reveal phylogenetically and functional informative features useful to reconstruct the evolution of elephantoid enamel. Studies of the adaptations and evolution of proboscidean enamel have focused so far on molars. Nevertheless, given the possibility of an independent evolution of the enamel at different tooth positions, the variation of the enamel throughout the dentition needs to be taken into consideration when using enamel microstructural characters to infer proboscidean diversity and phylogeny. The results obtained from this study demonstrate the generality, among elephantoids, of the basic microstructural features of Cuvieronius hyodon enamel, allowing the characterization of the Elephantoid Enamel (EE). The differentiation between incisor and molar enamel seen in elephantoids is shown to represent a primitive elephantiform trait, as it also occurs in Phiomia. The three-layered enamel of the cheek teeth appears as the sole synapomorphy of the Elephantoidea, though the character might be homoplastic within the Proboscidea. Characters of the prisms cross-section might be used, on the other hand, to define less inclusive clades within the Elephantoidea.     

Microstructural characteristics of hair of pleistocene mummy of “Bilibino horse” <Emphasis Type="Italic">Equus</Emphasis> sp.

The microstructure of hair of all mummified horses found in Northeastern Siberia has been studied for the first time in a comparative aspect by means of light optical and electron microscopy techniques. The possibility of using hair of horse mummies of different geological ages for a comparative analysis has been demonstrated. No fundamental differences were found in hair microstructure between the mummy of the “Bilibino” horse Equus sp. (geological age 58500 years) and mummified remains of the Lena horse Equus lenesis Russanov, 1968 (geological age 38 5000–29 500 years), which suggests their close relationship. It has been shown that morphological adaptations in the structure of the equine hair coat formed during the Pleistocene and Holocene under the specific climate conditions of Northeastern Siberia.     

Cranial anatomy and palaeobiology of the Miocene marsupial Hondalagus altiplanensis and a phylogeny of argyrolagids

New cranial material of Hondalagus altiplanensis, from the middle Miocene of southern Bolivia, allows a rediagnosis of the genus and an assessment of its palaeobiology and phylogenetic relationships with other argyrolagid marsupials. The new specimens demonstrate several derived (synapomorphic) cranial features shared by HondalagusArgyrolagus: a globular braincase, ventrally directed occipital condyles, a broad zygomatic arch, and a short, deep dentary with a flat and long coronoid notch. Hondalagus had powerful masticatory muscles and its cementum-encased hypselodont cheek teeth suggests it had a very abrasive diet. The deep fossae on the lateral aspect of the skull of argyrolagids, interpreted by Simpson as large, laterally-facing orbits, are actually sharply margined temporal fossae. Hondalagus has a very large carotid foramen medially situated within the suture of the basisphenoid and basioccipital. A phylogenetic analysis of five argyrolagid genera was conducted using 32 characters (16 cranial, 16 dental) and a didelphid and a caenolestid as outgroups. Hondalagus-Argyrolagus-Microtragulus form a monophyletic group with an undescribed gen. et sp. nov. (MACN-Ch-1305) from the lower Miocene (Colhuehuapian) of Argentina as its sister taxon. Proargyrolagus appears as sister group to the other taxa of argyrolagids.     

The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: cranial anatomy,functional morphology,taxonomy, and relationships

The cranial anatomy of the Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962 is described in detail for the first time on the basis of two principal specimens: the holotype (SAM‐PK‐K337) and referred skull (SAM‐PK‐K1332). In addition several other specimens that have a bearing on the interpretation of the anatomy and biology of Heterodontosaurus are described. The skull and lower jaw of Heterodontosaurus are compact and robust but perhaps most notable for the heterodont dentition that merited the generic name. Details of the cranial anatomy are revealed and show that the skull is unexpectedly specialized in such an early representative of the Ornithischia, including: the closely packed, hypsodont crowns and ‘warping’ of the occlusal surfaces (created by progressive variation in the angulation of wear on successive crowns) seen in the cheek dentition; the unusual sutural relationships between the bones along the dorsal edge of the lower jaw; the very narrow, deeply vaulted palate and associated structures on the side wall of the braincase; and the indications of cranial pneumatism (more commonly seen in basal archosaurs and saurischian dinosaurs). Evidence for tooth replacement (which has long been recognized, despite frequent statements to the contrary) is suggestive of an episodic, rather than continuous, style of tooth replacement that is, yet again, unusual in diapsids generally and particularly so amongst ornithischian dinosaurs. Cranial musculature has been reconstructed and seems to conform to that typically seen in diapsids, with the exception of the encroachment of M. adductor mandibulae externus superficialis across the lateral surface of the temporal region and external surface of the lower jaw. Indications, taken from the unusual shape of the occlusal surfaces of the cheek dentition and jaw musculature, are suggestive of a novel form of jaw action in this dinosaur. The taxonomy of currently known late Karoo‐aged heterodontosaurids from southern Africa is reviewed. Although complicated by the inadequate nature of much of the known material, it is concluded that two taxa may be readily recognized: H. tucki and Abrictosaurus consors. At least one additional taxon is recognized within the taxa presently named Lanasaurus and Lycorhinus; however, both remain taxonomically problematic and their status needs to be further tested and may only be resolved by future discoveries. The only other named taxon, Geranosaurus atavus, represents an invalid name. The recognition of at least four distinct taxa indicates that the heterodontosaurids were speciose within the late Karoo ecosystem. The systematics of Heterodontosaurus and its congeners has been analysed, using a restricted sample of taxa. A basal (nongenasaurian) position within Ornithischia is re‐affirmed. There are at least four competing hypotheses concerning the phylogenetic placement of the Heterodontosauridae, so the evidence in support of the various hypotheses is reviewed in some detail. At present the best‐supported hypothesis is the one which places Heterodontosauridae in a basal (non‐genasaurian) position; however, the evidence is not fully conclusive and further information is still needed in respect of the anatomy of proximate outgroups, as well as more complete anatomical details for other heterodontosaurids. Heterodontosaurids were not such rare components of the late Karoo ecosystem as previously thought; evidence also suggests that from a phylogenetic perspective they occupied a potentially crucial position during the earliest phases of ornithischian dinosaur evolution. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011.     

Unicorn “holotype” skeleton from the Late Pleistocene spotted hyena den site Sewecken-Berge (Germany)

Late Pleistocene Ice Age spotted hyena remains are described from the “Unicorn holotype skeleton” gypsum karst site Quedlinburg-Sewecken-Berge, Germany (Central Europe). The hyena population consists of adolescent to late adult individuals (96% of hyena NISP; 15% of megafauna NISP) indicating a commuting den site type. The comparisons to other European bone assemblages support hunting specialization on woolly rhinoceros (19% of NISP) and horses (27% of NISP). Specialization on bovids (Bison/Bos) can be added for this site. The megafauna contain few Eemian warm period remains of a large horse Equus ferus fossilis. Most (95%) of the megafauna is attributed to the Late Pleistocene glacial (Weichselian/Wuermian). Horse bones are dominated by distal leg elements from the smaller Przewalski horses Equus ferus przewalskii (26% of NISP). The Unicorn “holotype” skeleton originates from a composed horse skull, vertebrae and front legs, whereas the elephant remains added to this biologically not valid species must have been a straight-tusked elephant tusk.     

Aspects of masticatory form and function in common tree shrews,Tupaia glis

Tree shrews have relatively primitive tribosphenic molars that are apparently similar to those of basal eutherians; thus, these animals have been used as a model to describe mastication in early mammals. In this study the gross morphology of the bony skull, joints, dentition, and muscles of mastication are related to potential jaw movements and cuspal relationships. Potential for complex mandibular movements is indicated by a mobile mandibular symphysis, shallow mandibular fossa that is large compared to its resident condyle, and relatively loose temporomandibular joint ligaments. Abrasive tooth wear is noticeable, and is most marked at the first molars and buccal aspects of the upper cheek teeth distal to P². Muscle morphology is basically similar to that previously described for Tupaia minor and Ptilocercus lowii. However, in T. glis, an intraorbital part of deep temporalis has the potential for inducing lingual translation of its dentary, and the large medial pterygoid has extended its origin anteriorly to the floor of the orbit, which would enhance protrusion. The importance of the tongue and hyoid muscles during mastication is suggested by broadly expanded anterior bellies of digastrics, which may assist mylohyoids in tensing the floor of the mouth during forceful tongue actions, and by preliminary electromyography, which suggests that masticatory muscles alone cannot fully account for jaw movements in this species.     

Cranial anatomy of Shunosaurus, a basal sauropod dinosaur from the Middle Jurassic of China

Shunosaurus, from the Middle Jurassic of China, is probably the best‐known basal sauropod and is represented by several complete skeletons. It is unique among sauropods in having a small, bony club at the end of its tail. New skull material provides critical information about its anatomy, brain morphology, tooth replacement pattern, feeding habits and phylogenetic relationships. The skull is akinetic and monimostylic. The brain is relatively small, narrow and primitively designed. The tooth replacement pattern exhibits back to front replacement waves in alternating tooth position. The teeth are spatulate, stout and show well‐developed wear facets indicative of coarser plant food. Upper and lower tooth rows interdigitate and shear past each other. Tooth morphology, skull architecture, and neck posture indicate that Shunosaurus was adapted to ground feeding or low browsing. Shunosaurus exhibits the following cranial autapomorphies: emargination of the ventral margin of the jugal/quadratojugal bar behind the tooth row; postorbital contains a lateral pit; vomers do not participate in the formation of the choanae; pterygoid is extremely slender and small with a dorsal fossa; quadrate ramus of the pterygoid is forked; quadratojugal participates in the jaw articulation; tooth morphology is a combination of cylindrical and spatulate form; basipterygoid process is not wrapped by the caudal process of the pterygoid; trochlear nerve has two exits; occlusal level of the maxillary tooth row is convex downward, whereas that of the dentary is concave upward, acting like a pair of garden shears; dentary tooth count is 25 or more; and the replacing teeth invade the labial side of the functional teeth. Cranial characters among the basal sauropods are reviewed. As Shunosaurus is the earliest sauropod for which cranial remains are known, it occupies an important position phylogenetically, showing the modification of skull morphology from the prosauropod condition. Although the skull synapomorphies of Sauropoda are unknown at present, 27 cranial synapomorphies are known for the clade Eusauropoda. © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136 , 145?169.     

New information about <Emphasis Type="Italic">Irajatherium hernandezi</Emphasis> Martinelli,Bonaparte, Schultz &; Rubert 2005 (Eucynodontia,Tritheledontidae) from the upper triassic (Caturrita Formation,Paraná Basin) of Brazil

In this contribution, new specimens of the tritheledontid eucynodont Irajatherium hernandezi, from the Late Triassic (Caturrita Formation) of southern Brazil, are analyzed. The new material provides significant information about incisor count, canine size and shape, basicranial morphology, and other previously unknown aspects of skull and dentition. A cladistic analysis with inclusion of the new data supports the assignment of Irajatherium to Tritheledontidae, basal to Chalimininae and Pachygenelinae. Previously unknown characters of Irajatherium revealed by the new material include: the presence of three lower incisors; the first lower incisor is enlarged; the presence of large upper and lower canines with deep paracanine fossa on the maxilla; almost complete upper and lower postcanine tooth row with a pattern similar to that of other tritheledontids (e.g. Pachygenelus and Chaliminia); there is a conspicuous crest on the inner surface of the maxilla for the attachment of the inferred maxillary turbinates; partially confluent jugular foramen and fenestra rotunda within the jugular fossa, separated by a finger-like projection of the posterolateral wall of the opisthotic; and hypoglossal foramina located outside the jugular fossa. Irajatherium is a key taxon for understanding the early evolution of ictidosaurs, a group of cynodonts closely related to mammaliaforms, during the cynodont–mammal transition from the Late Triassic to Early Jurassic.     

Cranial morphology and taxonomic resolution of some dolphin taxa (Delphinidae) in Australian waters,with a focus on the genus Tursiops

Phylogenetic relationships in the family Delphinidae have been widely debated. We examined 347 skulls of Tursiops, Stenella, Delphinus, Steno, Lagenodelphis, and Sousa in order to resolve the phylogenetic position of Australian species of Tursiops. Five Tursiops type specimens were included. Cranial morphology was described using 2‐dimensional (2‐D) and 3‐dimensional geometric morphometrics (3‐GM), counts and categorical data. Analyses showed a clear morphological separation of Tursiops, including type specimens, from other genera. The three Stenella species did not cluster together. Stenella attenuata clustered with Delphinus delphis, and Stenella coeruleoalba with Lagenodelphis hosei. Length and width of the skull and rostrum were important discriminators in both methods. For 3‐D data, round vs. angular posterior skull shape distinguished some genera. Taxa that overlapped in the multivariate analyses had different mean tooth counts. Our study challenges genetic studies that identified Tursiops as polyphyletic, with T. aduncus closer to S. attenuata.     

Comparative parasitological examination on sympatric equids in the Great Gobi “B” Strictly Protected Area,Mongolia

The Przewalski’s horse (Equus caballus przewalskii) became extinct in the wild during the 1960s. Based on a successful captive breeding program, Przewalski’s horses were reintroduced to the Great Gobi Part “B” strictly protected area (SPA) in SW Mongolia in the late 1990s. The Asiatic wild ass (Equus hemionus hemionus), Przewalski’s horse, and sometimes domestic horses live sympatricly in the Gobi B SPA. Previously published data demonstrates that, as a result of their different requirements and utilization of the park’s resources, their home-range size and social structure differ. Parasitological examinations in the three equid species show how the factors “home range, social structure, and resource selection” significantly impact parasitic burden. Asiatic wild asses are potentially exposed to a higher risk of parasite re-infection due to their temporal aggregation in very large groups. This study demonstrates a highly significant greater parasite load in the Asiatic wild ass for the majority of parasites evaluated (Dictyocaulus arnfieldi, Trichostrongylus axei, Strongyloides westeri, Parascaris equorum) compared to Przewalski’s horses and domestic horses in the same habitat. Domestic horses had higher parasite loads for eggs of strongylids, eggs of anoplocephalidae, and Eimeria leuckarti. The potential risk of cross infection between sympatric living equids is high, as is the cross infection between ruminants and equids. Furthermore, this study reports for the first time the occurrence of lungworms in free-ranging Przewalski’s horses. Whereas, Asiatic wild asses and Przewalski’s horses seem to cope very well with the sometimes high parasite burden, Mongolian domestic horses manifested typical parasite burden symptoms.     

Largest known specimen of the genus Dakosaurus (Metriorhynchidae: Geosaurini) from the Kimmeridge Clay Formation (Late Jurassic) of England,and an overview of Dakosaurus specimens discovered from this formation (including reworked specimens from the Woburn Sands Formation)

We report the largest known British specimen of the metriorhynchid crocodylomorph genus Dakosaurus discovered offshore from Chesil Beach, Dorset, England (Kimmeridge Clay Formation). This specimen is large toothed, which has extreme enamel spalling on the labial surface, enlarged carinae (‘carinal flanges’), carinal wear, macroziphodont denticles, and the crown retains much of its labiolingual width along most of its apicobasal length. This suite of morphologies is unique to Dakosaurus. All known Kimmeridge Clay Formation Dakosaurus specimens are isolated tooth crowns. A skull previously referred to Dakosaurus lacks all the cranial apomorphies of D. maximus and D. andiniensis, and cannot be referred to this genus. Furthermore, the vast majority of putative Dakosaurus tooth crowns from the ‘Potton Sands’ ( = Woburn Sands Formation) do indeed represent Dakosaurus (as well as two Plesiosuchus specimens), and they most likely originate from the Kimmeridge Clay Formation.     

Taxonomic status of the hominine cranium KNM-ER 1813 (primates: Homininae) from the Plio/Pleistocene of Koobi Fora

The hominine cranium KNM-ER 1813, from the late Plio/Pleistocene of Koobi Fora, has been regarded recently by some authors as a female ofHomo habilis Leakey, Tobias, andNapier, 1964 and by others as an enigma. Reassessment of its cranial morphology, dental metrics, proportions, and a new detailed determination of its sex indicates that it does not conform with the diagnosis forH. habilis, and is probably a male. It is sympatric withH. habilis yet shows more primitive features and rather a closer affinity to the smaller, more primitive chronospeciesH. antiquus Ferguson, 1984, and is thus the first, nearly complete skull of our oldest known human ancestor.     

The impact of digging on craniodental morphology and integration

The relationship between the form and function of the skull has been the subject of a great deal of research, much of which has concentrated on the impact of feeding on skull shape. However, there are a number of other behaviours that can influence craniodental morphology. Previous work has shown that subterranean rodents that use their incisors to dig (chisel‐tooth digging) have a constrained cranial shape, which is probably driven by a necessity to create high bite forces at wide gapes. Chisel‐tooth‐digging rodents also have an upper incisor root that is displaced further back into the cranium compared with other rodents. This study quantified cranial shape and upper incisors of a phylogenetically diverse sample of rodents to determine if chisel‐tooth‐digging rodents differ in craniodental morphology. The study showed that the crania of chisel‐tooth‐digging rodents shared a similar place in morphospace, but a strong phylogenetic signal within the sample meant that this grouping was nonsignificant. It was also found that the curvature of the upper incisor in chisel‐tooth diggers was significantly larger than in other rodents. Interestingly, most subterranean rodents in the sample (both chisel‐tooth and scratch diggers) had upper incisors that were better able to resist bending than those of terrestrial rodents, presumably due to their similar diets of tough plant materials. Finally, the incisor variables and cranial shape were not found to covary consistently in this sample, highlighting the complex relationship between a species’ evolutionary history and functional morphology.     

Patterns of postnatal development in skulls of lynxes,genus Lynx (Mammalia: Carnivora)

Studies on ossification patterns and other ontogenetic events associated with postnatal cranial growth of wild felids are scarce. An analysis of developmental processes undergone by several cranial structures (presphenoidal and sphenooccipital synchondroses, temporal and sagittal crests, and deciduous and permanent teeth) during postnatal growth has been conducted on a sample of 336 specimens belonging to the four Recent species of lynxes (Lynx pardinus, Lynx lynx, Lynx rufus, and Lynx canadensis). Age has been estimated based on tooth replacement, skull size, and by counting the annual lines of cementum growth. Comparison of the results obtained for each of the four species reveal (1) a single pattern for both tooth replacement and ossification of the sphenooccipital synchondrosis, (2) two ossification patterns for the presphenoidal synchondrosis, (3) a common pattern for development of temporal ridges and sagittal crest showing different degrees of morphological expression, and (4) evidence suggesting the involvement of a heterochronic process, neoteny, in the morphological differentiation of several populations and species of the genus Lynx. These data also support the hypothesis that processes involved in the replacement of carnassials are based on functional requirements. © 1996 Wiley-Liss, Inc.     

南京汤山驼子洞的马科化石及其意义

200 0年在南京汤山葫芦洞直立人地点附近的驼子洞堆积中发现了又一处哺乳动物化石点。其中的马科化石有两种 :黄河马Equushuanghoensis和中国 (长鼻 )三趾马Hipparion(Proboscidipparion)sinense。这是自 1 95 9年发现黄河马化石以来首次发现黄河马的颅骨和完整的颊齿列标本。这两种马的同时出现说明含驼子洞动物群的堆积形成于早更新世。因此驼子洞堆积的发现是江宁地区下更新统的首次记录。驼子洞的黄河马和长鼻三趾马均为这两类马在秦岭淮河以南的首次记录 ,并反映了在早更新世曾发生过北方动物群跨越长江的南迁事件。     

Cranial ontogeny in the Puma lineage,Puma concolor,Herpailurus yagouaroundi,and Acinonyx jubatus (Carnivora: Felidae): a three‐dimensional geometric morphometric approach

The Puma lineage is a monophyletic group that includes three living species: Puma concolor, Herpailurus yagouaroundi, and Acinonyx jubatus. It has been analysed from ecological and taxonomic perspectives, but their cranial ontogeny has been poorly studied. In this study, we assessed the cranial shape and size variation through three‐dimensional geometric morphometric techniques, and explored the acquisition of definitive shape and size in relation to key life‐history events. Each species occupied different locations in the shape morphospace: A. jubatus and P. concolor showed shorter and wider skulls, with more expanded zygomatic arches, than H. yagouaroundi, which presented the most divergent pattern of change. Ontogeny was more similar between P. concolor and A. jubatus than between the closely related P. concolor and H. yagouaroundi. The evolution of ontogenetic change in the lineage seems to be more influenced by size. Changes detected between juvenile and adult skulls enhanced predatory skills, coincident with the change from a diet of milk to a carnivorous diet. Change patterns suggest that the skull is not morphologically conservative in the lineage, in contrast with other carnivores such as canids and hyaenids. The enlargement of the rostrum observed in some canids and the reinforcement of the bite mechanism of hyaenids were not detected in this group. © 2013 The Linnean Society of London