Print ISSN: 0031-0247
Online ISSN: 2274-0333
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Historical dicoveries of paleogene mammals
A new Pliocene Gerbillinae from South Africa
Physogaleus hemmooriensis, a new shark species from the early to middle Miocene of the north sea basin
Abstract book of the 18th Conference of the EAVP
Early Oligocene Fishes from Alabama, USA
Eocene (56) , Quercy Phosphorites (37) , Systematics (31) , Rodents (29) , Mammalia (26)
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Les Chiroptères du Miocène inférieur de Bouzigues. 1- Etude systématique.Bernard SigéKeywords: batsdoi: 10.18563/pv.1.3.65-133 Abstract In recent years, the techniques of chemical preparing have permitted a rich paleontologic material to be obtained from the phosporitic sediment of Bouzigues (Hérault, France). The fauna of this locality is comprised of quite varied microvertebrates, amphibians, reptiles, birds, mammals. Twenty five species of the latter, belonging to seven orders, are today known from the site. Among them, the numerous rodents have allowed L. Thaler to chronologically situate this fauna in the Zone of Laugnac (<< late Aquitanian ›> of some authors). Article infos Published in Vol. 01, Fasc. 3 (1968) |
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Morphological description and identification of an extraordinary new elephant cranium from the early Pliocene of Ileret, Kenya
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New murids and gerbillids (Rodentia, Mammalia) from Pliocene Siwalik sediments of India.Rajeev PatnaikKeywords: Dental morphology; evolution; new species of murids and gerbillids; phylogenetic relationships; SystematicsAbstract Murids and gerbillids (Rodentia, Mammalia) recovered from four Upper Siwalik localities; Moginand (around 3.5-4.5 m.y.), Kanthro (around 2.5 m.y.), Ghaggar (around 2 m.y.) and Nadah (around 1.8-2 m.y.) are described herein. A comparison of Mus linnaeusi sp. nov. reveals its close relationship towards the house mouse Mus musculus. In contradiction to earlier proposals that Golunda migrated to the Indian subcontinent from Africa sometime during Late Pliocene, it is suggested here that Golunda (in the form of Golunda tatroticus sp. nov.) evolved from Parapelomys robertsí of Late Miocene deposits of Siwaliks. Golunda tatroticus sp. nov. exhibits a progressive relationship to the extant Indian Bush Rat Golunda ellioti through Golunda kelleri and Golunda sp. Tatera pinjoricus sp. nov. is considered here to be a link between the extinct Abudhabia kabulense and the extant Tatera indica. Article infos Published in Vol. 26, Fasc. 1-4 (1997) |
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Evolution et extinction des reptiles marins au cours du Mésozoïque.Nathalie BardetKeywords: Crocodiles; evolution; Extinctions; faunal assemblages; Helveticosaurs; Hupehsuchians; Ichthyoaurs; lizards; Marine Reptiles; Mesozoic; Nothosaurs; Pachypleurosaurs; Placodonts; Plesiosaurs; Snakes; Thalattosaurs; Turnovers; TurtlesAbstract An interpretation of the marine reptile fossil record, based on the existing litterature and complemented by the review of ancient collections and the study of new material, permits a better understanding of Mesozoic marine ecosystems. An inventory of the marine reptiles known from the Lower Triassic to the Paleocene is presented: 46 families, about 200 genera and 400 species have been recorded. This data base includes commentaries about systematics, stratigraphical ranges and geographical distribution of taxa. Marine reptiles include a mosaic of not necessarily closely related groups: ichthyosaurs, thalattosaurs, hupehsuchians, pachypleurosaurs, placodonts, nothosaurs, plesiosaurs, pliosaurs but also crocodiles, lizards, snakes, turtles. The diversity studies reveal that the fossil record of marine reptiles has been punctuated by two mass extinctions, during the Middle-Upper Triassic transition and at the Cretaceous-Tertiary boundary. The Jurassic-Cretaceous and Cenomanian-Turonian boundaries (the latter marked by the disappearance of ichthyosaurs) are potential crisis periods, but current data are not sufficient to reach conclusions. The Ladinian-Carnian transition is characterized by the disappearance of 64 % of families and affects essentially coastal forms. This extinction coincides with an important regressive phase. During the Upper Triassic, a faunal reorganisation within marine reptiles leads to the progressive disappearance of near-shore forms and to the development of pelagic groups. During the Maastrichtian-Danian crisis, 36% of families died out. Large-sized pelagic forms such as mosasaurs and elasmosaurs were the most affected and their extinction seems to have been rather sudden. On the other hand, pliosaurs and protostegid turtles became extinct, but were already declining. The survivors were near-shore forms such as crocodiles, snakes and some turtles and they may have taken refuge in freshwater environments. A break in the food chain based on phytoplankton is proposed as an extinction scenario for pelagic forms. Article infos Published in Vol. 24, Fasc. 3-4 (1995) |
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First Neogene Otonycteris (Chiroptera: Vespertilionidae) from Ukraine: its biostratigraphic and paleogeographic significance.Valentina V. RosinaKeywords: bats; East Europe; Gritsev; Late Miocene; Mammaliadoi: 10.18563/pv.39.1.e2 Abstract A new species, Otonycteris rummeli nov. sp., is described from the Late Miocene site Gritsev (MN 9) in the Ukraine. Otonycteris rummeli nov. sp. differs from those of most vespertilionids, except recent Otonycteris, Antrozous and Early Miocene Karstala silva, in having a well-developed entocingulid at the foot of the trigonid valley in the lower molars. The morphological resemblance of Otonycteris, Antrozous and Karstala is apparently a case of convergence in the evolution of the Old and New Worlds bat faunas. From at least the Middle Miocene the range of Otonycteris distribution spread to the whole of Central Europe and such a situation continued during the whole Late Miocene. This indicates a more arid climate in Europe during the Upper Miocene compared to the Quaternary. The reduction of the distribution range of Otonycteris and its extinction in most of the territory of Europe could have been caused by the global climatic cooling and increasing glacial cycle amplitude during the onset of the Quaternary. Article infos Published in Vol.39-1 (2015) |
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Analysis of mammalian communities from the late Eocene and Oligocene of southern FranceSerge LegendreKeywords: Late Eocene; Mammalian communities; Oligocene; Quercy; Southern FranceAbstract Valverde's cenogram method is used to analyse mammalian communities from the late Eocene to late Oligocene of southern France, mainly from the "Phosphorites du Quercy". Cenogram analysis involves plotting the size of each component species in a fauna on a semilog diagram in rank order, permitting fossil faunas to be compared with Recent ones. The configurations of Recent communities serve as models for establishing the general environmental characteristics of fossil mammalian faunas. This method of analysis applied to faunal sequence can reveal major and sudden ecological perturbations. The paleobiogeographical event (i.e. the mammalian immigration wave) at the Eocene-Oligocene Boundary in western Europe, known as the «Grande Coupure", is here shown to represent a drastic and sudden ecological change: late Eocene tropical environments in Europe deteriorated rapidly turning to subdesert or desert environments al the beginning of the Oligoccne. Article infos Published in Vol. 16, Fasc. 4 (1986) |
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The geologically youngest remains of an ornithocheirid pterosaur from the late Cenomanian (Late Cretaceous) of northeastern Mexico with implications on the paleogeography and extinction of Late Cretaceous ornithocheiridsEberhard D. Frey, Wolfgang Stinnesbeck, David M. Martill, Héctor E. Rivera-Sylva and Héctor Porras MúzquizKeywords: Coahuila; Late Cenomanian; north-eastern Mexico; Ornithocheiridae; Pterosauriadoi: 10.18563/pv.43.1.e4 Abstract Ornithocheirid pterosaurs were the largest of the toothed pterodactyloids and had a worldwide distribution, although their fossil record is fragmentary, with the exception of the north-eastern Brazilian Crato and Santana Formations (Aptian, ?Albian, Early Cretaceous). With Istiodactylidae, they were also the only toothed pterosaurs that survived into the Cenomanian (Late Cretaceous), becoming extinct at the end of this period. Here we report on an ornithocheirid metacapus from the Late Cenomanian laminated limestone of north-eastern Mexico discovered about 120 km north-west of Ciudad Acuña, northern Coahuila at the south banks of Rio Bravo. The specimen comprises a fragmentary distal syncarpal, a crushed but complete metacarpal IV, two fragmentary preaxial metacarpals and a possible fragmentary terminal left wing finger phalanx. It represents the geologically youngest known ornithocheirid worldwide. We suggest that ornithocheirid pterosaurs may have become extinct because of massive sea level fluctuations during the mid to late Cretaceous that may have obliterated their breeding sites on coastal plains and low lying islands. Article infos Published in Vol 43-1 (2020) |
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New records of the pantodont Archaeolambda from the Paléocène of southern ChinaSuyin Ting, Judith A. Schiebout and Jianjian ZhengKeywords: Archaeolambda; China; Paleocene; PantodontAbstract Two new finds of pantodont materials from southern China, assigned to Archaeolambda, are described in this paper. One, a new species from the Nanxiong Basin, Guangdong Province, is similar to Alcidedorbignya inopinata from the early Paleocene of Tiupampa, Bolivia in size. It provides reliable evidence of the occurrence of Archaeolambda in the early-middle Paleocene of southern China. The second find includes specimens of Archaeolambda sp. cf. A. planicanina from the ?late Paleocene of Hengyang Basin, Hunan Province, which are the first record of a fossil mammal from the area near Hengyang city. The only vertebrate fossils previously found here were two genera of crocodiles discovered in 1938. This find sheds new light on the local biostratigraphy. Article infos Published in Vol. 25, Fasc. 2-4 (1996) |
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Mammifères de l'Ilerdien Moyen (Eocène inférieur) des Corbières et du Minervois (Bas-Languedoc, France). Systématique, Biostratigraphie, Corrélations.Bernard MarandatKeywords: Biostratigraphy; Corbières; correlations; Early Eocene; Ilerdian; Mammalia; Minervois; Paleobiogeography; Southern FranceAbstract Mammal-bearing localities have been discovered in the marine and lacustrine series of the middle Ilerdian (Lowermost Eocene) from Southem France (Minervois and Corbières). In the localities of Fordones, Monze, Fournès, and La Gasque, thirty mammal species have been identified. Among others, they include ischyromyid rodents (Microparamys and Pseudoparamys), paromomyid and adapid primates (Arcius and Donrussellia), new insectivores, condylarths, and a dyspternine pantolestid. These faunas provide new informations on the early Eocene Mesogean faunas of Rians and Palette. The assemblages of primates and rodents from Fordones support good correlations with Palette which was recently placed near the standard-level of Dormaal (MP 7). In fact, Palette and Fordones could be even older than Dormaal. Consequently, there seems to be a relatively important temporal gap between the late Paleocene of Cernay and the Sparnacian of Dormaal. This gap could be partly filled with the Mesogean faunas of Palette, Fordones, and Silveirinha. On the basis of these new mammal faunas the marine middle Ilerdian is proved to be older than the Cuisian stage of the Paris Basin. With regards to the position of the Fordones fauna at the top of the NP 10 calcareous nannoplankton biozone, the westem European paleomammalogists Paleocene/Eocene boundary could be situated between the NP 9 and NP 10 biozones. Article infos Published in Vol. 20, Fasc. 2-3 (1991) |
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Evolution des Aplodontidae Oligocènes EuropéensNorbert Schmidt-Kittler and Monique Vianey-LiaudKeywords: Aplodontidae; Europe; OligoceneAbstract Until now Aplodontidae of the European Oligocene have been documented by four species only. The phylogenetic relations remained obscure. as the distribution of only one species has been known in some detail. New material made it possible to define the stratigraphic range of two of the already existing species (Plesispermophilus angustidens, Sciurodon cadurcense) and to follow their development during the Oligocene beginning with the event of the « Grande Coupure ››. Sciurodon remained nearly without change until the end of the Middle Oligocene. Plesispermophilus angustidens split into two distinct phyletic lines, one of which (P. macrodon n. sp.) reaching considerable size, is represented till the beginning of the Upper Oligocene (Pech de Fraysse, Gaimersheim). The other line leads to Plesispermophilus ernii (basal Upper Oligocene of Burgmagerbein 1. terminal Upper Oligocene of Coderet). Besides the already known forms a new small-sized species (P. atavus n. sp.) is described, which by its primitive features closely resembles the genus Plesispermophilus. Two other small-sized species already known from the Upper Oligocene (? P. argoviensis) and Lower Miocene (? P. descedens) seem to be closely related to the new species. It cannot be decided whether they are descendents of this line or have developed independently, because of their poor fossil record. Article infos Published in Vol. 09, Fasc. 2 (1979) |
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Skeleton of early Eocene Homogalax and the origin of PerissodactylaKenneth D. RoseKeywords: Eocene; Homogalax; Perissodactyla; Skeletal AnatomyAbstract The first good skeletal remains of Homogalax protapirinus from the Wasatchian of the Bighorn Basin, Wyoming, indicate that this primitive tapiromorph was more plesiomorphic in many features than primitive equoids including Hyracotherium. Compared to Hyracotherium, Homogalax more closely resembles Phenacodonta (the closest outgroup of Perissodactyla for which postcrania are known) in various details of articular surfaces, muscle attachments, and proportions of the humerus, manus, and pes.Among known taxa, Homogalax most nearly approximates the plesiomorphic postcranial skeletal anatomy of Perissodactyla. Article infos Published in Vol. 25, Fasc. 2-4 (1996) |
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A new rodent from Quaternary deposits of the Canary Islands and its relationships with Neogène and recent murids of Europe and Africa.Rainer Hutterer, Nieves Lopez-Martinez and Jacques MichauxKeywords: Canary Islands; Holocene; Island evolution; Muridae; PHYLOGENY; Rodents; SpainAbstract A peculiar new rodent, Malpaisomys insularis nov. gen., nov. sp., is described from subfossil deposits of the eastern Canary Islands. The species shows some highly specialized skull features although its molars exhibit a mixture of primitive and derived characters among which a partial stephanodonty is most notable. A comparison of the new rodent with several Miocene to Holocene Muridae shows that Malpaisomys possibly shares a common ancestor with Acomys and Uranomys. Article infos Published in Vol. 18, Fasc. 4 (1988) |
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A pangolin (Manidae, Pholidota, Mammalia) from the French Quercy phosphorites (Pech du Fraysse, Saint-Projet, Tarn-et-Garonne, late Oligocene, MP 28)Jean-Yves Crochet, Lionel Hautier and Thomas LehmannKeywords: Oligocene; Pangolin; Pech du Fraysse; Quercy Phosphoritesdoi: 10.18563/pv.39.2.e4 Abstract Pangolins have never shown a high taxic diversity and their fossil record is scarce. We report here the first discovery of a partial humerus from late Oligocene deposits in Pech du Fraysse (MP28, France). The new specimen from Pech du Fraysse is described and compared to various extant and extinct species of pangolins. It shows a suite of morphological features very similar to the humeri discovered in Saint-André (MP 26), Solnhofen (Burdigalien), and Saulcet (Aquitanian), attributed here to Necromanis franconica. The description of the specimen from Pech du Fraysse allowed us to discuss the systematics of Paleogene and Neogene pholidotans. The differences between PFY 4051 and N. franconica on the one side, and N. quercyi on the other side, might be sufficiently important to justify a generic distinction. A comparison with extant species showed that N. franconica was likely terrestrial and fossorial based on its humeral morphology. Related dataset Article infos Published in Vol.39-2 (2015) |
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Enamel hypoplasia on rhinocerotoid teeth: Does CT-scan imaging detect the defects better than the naked eye?Manon Hullot and Pierre-Olivier AntoineKeywords: fossil teeth; method; micro-CT imaging; Rhinocerotoideadoi: 10.18563/pv.45.1.e2 Abstract Micro-CT imaging is an increasingly popular method in paleontology giving access to internal structures with a high resolution and without destroying precious specimens. However, its potential for the study of hypoplasia defects has only recently been investigated. Here, we propose a preliminary study to test whether hypoplastic defects can be detected with micro-CT (μCT) scan and we assess the costs and benefits of using this method instead of naked eye. To do so, we studied 13 fossil rhinocerotid teeth bearing hypoplasia from Béon 1 (late early Miocene, Southwestern France) as positive control and 11 teeth of the amynodontid Cadurcotherium (Oligocene, Phosphorites du Quercy, Southwestern France), for which enamel was partly or totally obscured by cement. We showed that all macroscopically-spotted defects were retrieved on 3D reconstructions and selected virtual slices. We also detected additional defects using μCT scan compared to naked eye identification. The number of defects detected using μCT was greater in the Cadurcotherium dataset (paired-sample Wilcoxon test, p-value = 0.02724) but not for our control sample (paired-sample Wilcoxon test, p-value = 0.1171). Moreover, it allowed for measuring width and depth of the defects on virtual slices (sometimes linked to stress duration and severity, respectively), which we could not do macroscopically. As μCT imaging is both expensive and time consuming while not drastically improving the results, we recommend a moderate and thoughtful use of this method for hypoplasia investigations, restricted for instance to teeth for which enamel surface is obscured (presence of cement, uncomplete preparation, or unerupted germs). Article infos Published in 45-1 (2022) |
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Paleobiology of Messel ErinaceomorphsGerhard StorchKeywords: Erinaceomorpha; Germany; Grube Messel; Lipotyphla; Middle Eocene; PaleobiologyAbstract Three erinaceomorph species are known from the early Middle Eocene of Grube Messel near Darmstadt, Germany, which are referred to the family Amphilemuridae. Pholidocercus hassiacus, Macrocranion tupaiodon, and Macrocranion tenerum showed extraordinary adaptations to their different life strategies, and several of their specializations are unknown among living insectivores. Pholídocercus was a well-defended robust animal with an opportunistic feeding strategy. Macrocraníon zupaiodon was a slender forest floor-dweller with saltatorial specializations to escape from predators; fishes were the preferred component of its omnivorous diet. Macrocranion tenerum exhibited a combination of both survival strategies, extremely elongated hind limbs for rapid and even ricochetal flight and a spiny exterior as an effective protective device; it was probably specialized for feeding on ants. Thus, closely related, omnivorous-insectivorous forest floor-dwellers could exploit the Messel ecosystem. Article infos Published in Vol. 25, Fasc. 2-4 (1996) |
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Relations phylétiques de Bachitherium filhol, ruminant de l'Oligocène d'Europe Occidentale.Denis Geraads, Geneviève Bouvrain and Jean SudreKeywords: Artiodactyla; Bachitherium; Cladistic analysis; France; Mammalia; Oligocene; RuminantiaAbstract A detailed comparative study of a complete skeleton of Bachitherium and a cladistic analysis of the sub-order Neoselenodontia lead us to propose a cladogram and a new classification of this group. The Tylopoda are the sister-group of the Ruminantia, which are chiefly defined by the fusion of the cuboid and navicular. Within this infra-order, Amphimeryx is the sister genus of a tetraselenodont group, in which the Hypertragulidae are well-separated group from a monophyletic group defined by the loss of trapezium, fusion of capitatum and trapezoid, and the isolation of the hypoconid on lower molars. The most primitive genera of this group, Lophiomeryx and Iberomeryx still have an open trigonid on the lower molars, but this is lingually closed in Archaeomeryx, sister-genus of the higher Ruminantia which have fused metatarsals and more evolved milk teeth. We divide them into two pan/orders : Tragulina (including the recent and miocene Tragulidae, and the North-American Leptomerycidae), and Pecora, with reduced lateral metacarpals and a new crest (telocristid) on the lower premolars. Within the Pecora, the upper molars of Gelocus are more primitive than those of Bachitherium (a genus with many autapomorphies in the dentition) itself more primitive than the group Prodremotherium + Eupecora, with fused metacarpals. We consider the Eupecora (including several genera without frontal appendages) to be monophyletic. Article infos Published in Vol. 17, Fasc. 2 (1987) |
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First early Eocene tapiroid from India and its implication for the paleobiogeographic origin of perissodactylsThierry Smith, Floréal Solé, Pieter Missiaen, Rajendra Rana, Kishor Kumar, Ashok Sahni and Kenneth D. RoseKeywords: Ceratomorpha; Helaletidae; Paléogène; Tapiromorpha; Vastandoi: 10.18563/pv.39.2.e5 Abstract The presence of cambaytheres, the sister group of perissodactyls, in western India near or before the time of collision with Asia suggests that Perissodactyla may have originated on the Indian Plate during its final drift towards Asia. Herein we reinforce this hypothesis by reporting two teeth of the first early Eocene tapiromorph Perissodactyla from the Cambay Shale Formation of Vastan Lignite Mine (c. 54.5 Ma), Gujarat, western India, which we allocate to a new genus and species, Vastanolophus holbrooki. It presents plesiomorphic characters typical of the paraphyletic “Isectolophidae,” such as small size and weak lophodonty. However, the weaker hypoconulid and low paralophid, higher cusps, lower cristid obliqua, and the lingual opening of the talonid are found in Helaletidae, the most primitive tapiroid family. V. holbrooki, gen. et sp. nov., may be the oldest and the most primitive tapiroid, suggesting that at least tapiroid perissodactyls originated on India. Article infos Published in Vol.39-2 (2015) |
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The Pleistocene vertebrate fauna of Robinson Cave, Overton County, TennesseeJ. E. Guilday, H. W. Hamilton and A. D. Mc CradyKeywords: Fauna; Mammalia; Pleistocene; Tennesseedoi: 10.18563/pv.2.2.25-75 Abstract A late Pleistocene deposit of 60 species of vertebrates and 12 of invertebrates is described from Robinson Cave, Overton County, Tennessee, U.S.A. Forty-eight species of mammals are represented by at least 2,483 individuals; 10 % are extinct, 10 % occur in the state only as boreal relicts in the Great Smoky Mountains; 23 % no longer occur as far south as Tennessee; 57 % occur at or near the site today. Nínety-one percent of the Recent mammal species can be found living today in the Minnesota-Wisconsin area, approximately 10 degrees farther north. Fluorine analysis suggests a long period of accumulation. The following 10 mammalian species are recorded from Tennessee for the first time. Sorex arcticus, Microsorex hoyi, Citellus tridecemlineatus, Clethrionomys gapperi, Microtus pennsylvanicus, Synaptomys cooperi, Synaptomys borealis, Zapus nudsonius, Napaeozapus insignis, Martes americana. Six additional species are present as boreal relicts in the Great Smoky Mountains of eastern Tennessee but not at the site today : Sorex cinereus, Sorex dispar, Sorex palustris, Parascalops breweri, Glaucomys sabrinus, Mustela nivalis. Six forms are extinct: Canis dirus, Ursus americanus amplidens, Sangamona furtiva, Dasypus bellus, Mammut americanus,Megalonyx jeffersoni. Twenty-six additional species of mammals, all of the snails, birds, reptiles, and amphibians recovered from the fauna still inhabit the area today: The fauna is indicative of a cold-temperate climatic episode associated with the Wisconsin glaciation, but may be chronologically mixed. Article infos Published in Vol. 02, Fasc. 2 (1969) |
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Les oiseaux aquatiques (Gaviiformes à Anseriformes) du gisement Aquitanien de Saint-Gerand-le-Puy (Allier, France): Révision systématique.Jacques ChenevalKeywords: Aves; Early Miocene; Osteology; Palaeoecology; SystematicsAbstract Six orders of birds adapted to aquatic life are represented among the numerous avifauna of "Saint-Gérand-le-Puy": Gaviiformes, Procellariiformes, Pelecaniformes, Ciconiiformes, Phoenicopteriformes, and Anseriformes. The present study of this avifauna proposes several changes in systematics:- Procellariiformes: Puffinus arvernensis does not belong in Procellariidae but in Diomodeidae, and it is transferred to the fossil genus Plotornis previously described in the Middle Miocene of France. - Pelecaniformes: Phalacrocorax littoralis remains in Phalacrocoracidae; P. míocaenus is different from the modern species, and is transferred to the new genus Nectornis. Empheresula arvernensis, described in the Oligocene deposits of Gannat, seems to be present in Saint-Gérand-le-Puy too. Pelecanus gracilis shows many differences from the modern species, and belongs to the new genus Miopelecanus, - Ciconiiformes: Ardea formosa nom. oblit. is a synonym of Proardeola walkeri. - Anseriformes: a new species closely related to swans is described, and belongs to the fossil genus Cygnopterus, of the Middle Oligocene of Europe; this species is called C. alphonsi. The ecology of each species is suggested by comparison with that of its nearest living relatives, and by study of osteological adaptations. Article infos Published in Vol. 14, Fasc. 2 (1984) |
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Le genre Leptolophus (Perissodactyla, Mammalia): morphologie et histologie dentaires, anatomie cranienne, implications fonctionnelles.Jean-Albert RemyKeywords: dental histology; Eocene; functional anatomy; Palaeotheriidae; skull anatomy; Southern France; SystematicsAbstract A strong lophodonty, an extreme heterodonty, some hypsodonty and regular overlayings of coronal cement are prominent features of the genus Leptolophus (Palaeotheriinae = Palaeotheriidae s.s.). The histological pattern of the teeth unusually joins type II enamel prisms, characteristic of advanced ungulates, together with archaic features, such as an almost complete lack of Hunter-Schreger zonation and a weak expanse of peritubular dentine. The skull is narrow and slender, with an elongated ante-orbital facial region, a moderately notched nasal aperture, a rather elongated post-canine diastem, parallel zygornatic arches and a fairly dorsally located squamoso-mandibular joint.The functional analysis brings to light "ectolophodont" masticatory cycles with two phases, in which maximum power was applied, contrary to equíds, on hindmost teeth; likewise, skull accomodations to increasing height of the teeth are quite different. This study leads to the assumption that Leptolophus may have been light mammals, living in rather open surroundings, browsing on herbaceous plants or leaves cropped close to the ground. Moreover, it appears that it could have been some inadequacy of dental structures to the dietary, which leaded to quick wear of the teeth and to many enamel notches, but had been somewhat balanced by the early increase of hypsodonty, not induced in such a case by a biotop deterioration (as it will happen at the end of the Eocene). This ínadaptation might account for the short duration of the genus Leptolophus, whose the 3 species, L. stehlini, L. nouletí and L. magnus n. sp. are indeed confined in the level MP 16. Its geographical spreading (as far as known, South of western Europe) and the morphological pattern of its dentition suggest that this genus would have been related to early upper Eocene endemic spanish forms. Article infos Published in Vol. 27, Fasc. 1-2 (1998) |
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