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Observations sur l'anatomie crânienne du genre Palaeotherium (Perissodactyla, Mammalia): mise en évidence d'un nouveau sous-genre, Franzenitherium
Jean-Albert Remy
Keywords: Palaeotherium; Paléogène; Perissodactyla; skull anatomy; Systematics
 
  Abstract

    The skull remains referred to the genus Palaeotherium are recorded and described. Biometrical tests are made to elucidate intrageneric allometric relationships and to allow comparisons with various other perissodactyls. Apart from the well known shortness of post canine diastems and deepness of the narial opening, the genus is characterized by a great lengthening of the splanchnocranium, owing to a spreading of the post-orbital facial region, by a reduced area of the eye-socket and by the prevalence of the temporal muscle with regard to the masseter; this original shape of the masticatory apparatus needs to be related to the morphology of the jugal teeth and particularly to their  asymmetrical semi-hypsodonty.
        These animals, whose running ability was evidently poor, appear to have been adapted to rather closed environments, feeding on relatively soft vegetable matter; olfactory sense was likely to play a leading part in interindividual and environmental relationships. Such evolutionary trends might explain the disappearance of most of them, as clirnatic conditions deteriorated at the end of the Eocene, before the "Grande Coupure" which affected mammalian faunas at that time.
          Although the present paper is not directly concemed with phylogenetics, it invalidates the supposed ancestor-descendant relationship between P. castrense and P. magnum, and it suggests a possible emergence of the P. medium lineage from a P. siderolithicum stock. Moreover, the structure of the post-orbital facial area allows the  erection of a new sub-genus, Franzenitherium, for the  species lautricense and duvali.

      


  Article infos

Published in Vol. 21, Fasc. 3-4 (1992)

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Les mammifères Montiens de Hainin (Paléocène moyen de Belgique) Part1: Multituberculés.
Monique Vianey-Liaud
Keywords: Belgium; Hainin; Mammals; multituberculates; Paleocene
 
  Abstract

    The Montian locality of Hainin (Hainaut, Belgium) yielded about twenty teeth of Multituberculates. They are very peculiar forms, showing no affinities, at the generic level, with those hitherto known from North America, Asia and Europe. They are referred to the new taxa Boffius splendidus nov. gen., nov. sp., Hainina belgica nov. gen., nov. sp., and H. godfriauxi nov. gen., nov. sp. They expose some common features, such as the advanced type of first upper molar. possessing at least three complete rows of cusps. Because of this, and also of the upper premolar reduction, Boffius splendidus appears as the most specialized form within the Ptilodontoidea suborder.
    Several other characters of Hainina seem to be less advanced, such as the great number of upper premolars and the simple cusp-formula of the first lower molar.
    Till now, only H. godfriauxi has been recovered within the Thanetian fauna from Cemay-les-Reims, where it is very poorly documented. 


  Article infos

Published in Vol. 09, Fasc. 4 (1979)

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Les rongeurs de l'Oligocène inférieur d'Escamps
Monique Vianey-Liaud
Keywords: Escamps; Quercy Phosphorites; Rodents; Theridomyidae
 
  Abstract

    La faune de Rongeurs d'Escamps (Lot) bien que relativement pauvre en espèces (dix) s'avère riche d'enseignement pour les Rongeurs de l'Oligocène inférieur d'Europe Occidentale. Cette periode semble caracterisée par une cladogenèse des Théridomyines. A Escamps, un nouveau genre (Patriotheridomys) est décrit ainsi qu'une nouvelle espèce de Theridomys. Avec Oltmamys platyceps, décrit ici plus complètement et désormais bien situé stratigraphiquement, les deux espèces précédentes constituent un ensemble original du Sud de la France. A la même époque, en Angleterre, Allemagne et Espagne, des espèces «régionales» de Théridomyinés se dersifient.  A côté de ces formes qui ne semblent pas franchir la «Grande Coupure» sont représentées deux lignées d'Issiodoromyinés (Elfomys sp et Pseudoltmomys cuvieri), une de Théridomyiné (T. (Blainvillimys) rotundidens) ainsi qu'un Gliridé, Gliravus priscus (que l'on différencie nettement de la deuxième lignée des Gliravus oligocènes : G.  meridionalis -> G. majori). On retrouve ces formes dans les gisements plus récents du niveau de Hoogbutsel où elles sont à peine plus évoluées. Le fait que les degrés évolutifs de ces lignées soient très proches laisse supposer que le laps de temps séparant les niveaux d'Ecamps et Hoogbutsel fut relativement court. 


  Article infos

Published in Vol. 06, Fasc. 3-4 (1975)

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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 3 - Les artiodactyles ruminants
Léonard Ginsburg and Herbert Thomas
Keywords: Artiodactyla; France; Montredon; Ruminentia; Upper Miocene
 
  Abstract

    The remains of Ruminantia are very rare at Montredon. No specific determination was possible. We have only one Micromeryx, one small cervid, one tragocere and one (?) gazella. The faunal spectrum is in good correlation with the general retreat of the cervids in the European upper Miocene, but in contrast it is not convenient for the bovids, which are in expansion at the same time. For them, we have to invoke the local ecological conditions.
      


  Article infos

Published in Vol. 18, Ext (1988)

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First report of Cylindracanthus (Osteichthyes) from the Eocene of India
Pankal Kumar, Rajeev Patnaik, Deepak Choudhary, Rohit Kumar and Wasim Abass Wazir
Keywords: Cylindracanthus; Eocene; histology; rostrum; Umarsar mine.

doi: 10.18563/pv.47.1.e2
 
  Abstract

    Fossils of the endangered sturgeons and peddlefishes are widely distributed. We here report for the first time the presence of one of the extinct osteichthyes genus Cylindracanthus (Liedy 1856a) from the Early Eocene lignite-bearing successions of the Kutch Basin, India. The present well preserved rostrum is characterised by numerous wedge-shaped components encircling the central canal that runs along its length, paired at the base and each wedge contributing to the formation of a ridge. The rostrum lacks teeth. The present find extends the palaeobiogeographical distribution of Cylindracanthus considerably and supports its Eocene age as dental remnants preserved in Cylindracanthus sp. shows a decrease in remanent dentition and tooth bases from the Cretaceous to the Eocene. Cylindracanthus is an useful palaeoenvironmental indicator as it has been found associated typically with deposits of nearshore marine environments. 


  Article infos

Published in 47-1 (2024)

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Contributions à l'étude des micromammifères du gisement Miocène supérieur de Montredon (Hérault). 1- Le gisement
Jean-Pierre Aguilar and Jean-Yves Crochet
Keywords: Hérault; Late Miocene; Micromammals; Montredon
 
  Abstract

    La localité fossilifère du Puech de Montredon, désignée plus communément sous le nom de Montredon, est située sur la commune de Montouliers (Hérault) à quelques 300 mètres de la limite avec le département de l'Aude. Elle a été découverte en 1845 par Narbonne, Directeur des Mines de La Caunette, et de très nombreux restes de vertébrés continentaux y ont été extraits. La plus ancienne mention de ce gisement dans la littérature semble être celle de Lartet (1859) qui signale que "M. Jourdan, de Lyon, a constaté à Montredon, près de Bize (Aude), l'association des restes de Dinotherium avec l'Hipparion". 


  Article infos

Published in Vol. 12, Fasc. 3 (1982)

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Un crane de Chalicothere (Mammalia, Perissodactyla) du Miocène supérieur de Macédoine (Grèce) : remarque sur la phylogénie des Chalicotheiinae
Louis de Bonis, Geneviève Bouvrain, George D. Koufos and Pascal Tassy
Keywords: Chalicotheriidae; Cladistics; Greece; Miocene; Perissodactyla; PHYLOGENY
 
  Abstract

    The discovery in the Turolian (Late Miocene) of Dytiko 3 (Macedonia, Greece) of a complete skull with mandibles and cervical vertebrae, atlas and epistropheus, is a very important contribution to the knowledge of the subfarnily Chalicotheríinae. After the description, the comparison with other specimens of Miocene chalicotheres permits the revival of the generic name Macrotherium with a new species M. macedonicum. This genus is mainly characterized by a short snout and an inflated cerebral skull. It coexists during the Miocene with Chalicotherium. A cladistic analysis leads to conclusion that the species which has been described from the Early Middle Miocene of Rusinga must be identified as the type-species of a new genus: Butleria.





      


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Published in Vol. 24, Fasc. 1-2 (1995)

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Pairomys et Ectropomys : la fin d'une ambiguïté ; mise au point sur les Oltinomyinae et Remyinae (Rodenia, Theridomyidae).
Monique Vianey-Liaud, Norbert Schmidt-Kittler and Pablo Pelaez-Campomanes
Keywords: PHYLOGENY; taxonomy; Theridomyidae; Upper Eocene
 
  Abstract

    The description of new material of the Upper Eoœne of France, Southem Germany and Spain together with the restudy of the material described by Thaler (1966b) as Pairomys allows to confirm the validity of the genus Ectropomys up to know controversally discussed. As a consequence the subfamily Remyinae and Oltinomyinae can be defined precisely. The study of the dental characters shows that the Remyinae in fact belong to the Theridomyidae and represent a derived evolutionary unit within this family. The Oltinomyinae together with the Theridomyinae and Issiodoromyinae very probably form a monophyletic unit. 


  Article infos

Published in Vol. 23, Fasc. 1-4 (1994)

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Hyracodontids and rhinocerotids (Mammalia, Perissodactyla, Rhinocerotoidea) from the Paleogene of Mongolia
Demberelyin Dashzeveg
Keywords: Hyracodontidae; Mongolia; Paléogène; Perissodactyla; Rhinocerotidae
 
  Abstract

        Two families are reviewed (Hyracodontidae and Rhinocerotidae) from the Paleogene of Mongolia. The following taxa are described from the former family:  Triplopus? mergenensis sp. nov., Prohyracodon meridionale CHOW, Prohyracodon? parvus sp. nov., Forstercooperia ergiliinensis GABUNIA & DASHZEVEG, Ardynia praecox MATTHEW & GRANGER, A. mongoliensis (BELIAYEVA), Ardynia sp., Urtinotheríum sp. (or Indricotherium) and Armania asiana GABUNIA & DASHZEVEG. All of them are from the Paleogene of the eastem Gobi Desert The hyracodontid Pataecops parvus RADINSKY is described from a new locality, Menkhen-Teg (Middle Eocene), in the Valley of Lakes.
        In the second family, a new species of Ronzotherium, R. orientale sp. nov. has been recognized from the Oligocene of Ergilin Dzo and Khoer Dzan of the eastem Gobi Desert. Ronzotherium sp. and Allacerops sp. have been described from the Oligocene of Khoer Dzan. The genus Ronzotherium, formerly known from the Oligocene of eastem Europe, has been reliably established in the Oligocene fauna of Mongolia. The genus Symphysorrachis BELIAYEVA, 1954, previously believed to be a junior synonym of Ronzotherium, is here resurrected.
        Descriptions are provided for key localities in the Eocene and Oligocene of Mongolia and the adjacent territories of northern China, containing fossil Hyracodontidae and Rhinocerotidae. In addition, the question of the Eocene-Oligocene boundary in these Mongolian and Chinese sections is discussed. Paleontological evidence has been used to correlate Eocene-Oligocene boundary layers in the eastem Gobi Desert (Mongolia) and Inner Mongolia (China). A brief discussion is provided on the phylogenetic affinities of the genera within the family Hyracodontidae. 


  Article infos

Published in Vol. 21, Fasc. 1-2 (1991)

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Les Entélodontes des phosphorites du quercy
Michel Brunet
Keywords: Entelodontes; Quercy Phosphorites
 
  Abstract

    The entelodonts of the Quercy phosphorites are essentially known from isolated teeth. The skull remains attributed to Entelodon magnum by Kowalewsky in 1876 and the type left mandible of Enteladon depereti RÉPELIN, 1918 do not belong to this family. From a morphologic point of view, the teeth from Quercy are quite comparable to those from the type localities of E. magnum and E. deguilhemi. In the absence of distinctive anatomical criteria between E. magnum (small species from the level of Ronzon) and E. deguilhemi (large species from the level of Villebramar) they are referred, according to their size, to one or the other of these two species. However, some of them are intermediate in size. Their existence speaks in favor of a close relationship between E. magnum and E. deguilhemi and confers a real stratigraphic interest to these entelodonts of Western Europe. Finally, some anatomical characters (notch on the mesial border of P4, presence of a paraconid joined to the metaconid, trigonid higher than talonid) considered until now as peculiar to the North American Archaeotherium and not yet cited in its European contemporary Entelodon have been brought to light on the teeth from Quercy.

      


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Published in Vol. 06, Fasc. 1-2 (1974)

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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 10 - Conclusions générales
Jacques Michaux
Keywords: Mammalia; Montredon; Upper Miocene
 
  Abstract

    Le présent volume traite des lagomorphes, carnivores, artiodactyles, périssodactyles et proboscidiens de la faune de Montredon (Hérault). Il clôt la monographie de ce célèbre gisement d'âge miocène supérieur du Languedoc, dont la première partie, relative aux rongeurs, insectivores et chiroptères, fut publiée en 1982.
    [...] 


  Article infos

Published in Vol. 18, Ext (1988)

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Première occurrence d'un mégachiroptère ptéropodidé dans le Miocène moyen d'Europe (Gisement de Lo Fournas-II, Pyrénées-Orientales, France).
Jean-Pierre Aguilar, Marc Calvet, Jean-Yves Crochet, Serge Legendre, Jacques Michaux and Bernard Sigé
Keywords: Europe; First occurence; Megachiroptera; Middle Miocene; Teeth
 
  Abstract

    A lot of isolated teeth of a pteropodid fruit bat has been recently found within an assemblage of micromammals recovered from a karstic fissure filling named Lo Fournas-Il near the locality of Baixas (Pyrénées-Orientales, France). The fauna is Middle Miocene Serravallian age. The fossil fruit bat appears morphologically close to Rousettus; its size is that of a recent medium-sized fruit bat. While the fruit bats are very poorly known as fossils, this discovery shows that one of their recent types of dentitions was perfectly established by Middle Miocene times, and supports the presumed long geologic story of the suborder. One of the major invasions of the Old World fruit bats, supposed originated from SE Asia, reached up to Europe. A suborder unit is added to the miocene fauna of this continent. 


  Article infos

Published in Vol. 16, Fasc. 3 (1986)

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The digital endocast of Necrolemur antiquus
Arianna Harrington, Gabriel Yapuncich and Doug Boyer
Keywords: brain evolution; Eocene; Omomyiforms; Primates

doi: 10.18563/pv.43.2.e1
 
  Abstract

    The study of endocasts, or casts of the endocranial space, have played an important role in shaping understanding of mammalian, and particularly primate, brain evolution. Recently, the reconstructions of three-dimensional virtual endocasts from high-resolution computed tomography images have allowed for the visualization and quantification of endocasts in several Paleocene and Eocene primate species. Here we present the virtual endocast of MaPhQ 289 (informally known as the Montauban 9 skull), a specimen of Necrolemur antiquus Filhol 1873, a middle to late Eocene European primate of the family Microchoeridae. The virtual endocast of MaPhQ 289 reveals a lissencephalic surface morphology with expanded temporal poles and minimal overlap of the cerebellum or olfactory bulb by the cerebrum, which closely resembles the morphology of the endocast of its contemporary relative, Microchoerus erinaceus (Primates, Microchoeridae). MaPhQ 289 yields an endocranial volume (ECV) of 2.36 cm3, about 60% smaller than the volume of the most commonly cited ECV of N. antiquus. Thus, the size of the brain of N. antiquus relative to its body size is likely to be smaller than has been reported in previous literature, highlighting the importance of corroborating older ECV estimates with new evidence using 3-D imaging techniques. 



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  Article infos

Published in 43-2 (2020)

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Les oiseaux aquatiques (Gaviiformes à Anseriformes) du gisement Aquitanien de Saint-Gerand-le-Puy (Allier, France): Révision systématique.
Jacques Cheneval
Keywords: Aves; Early Miocene; Osteology; Palaeoecology; Systematics
 
  Abstract

    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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Les mammifères Montiens de Hainin (Paléocène moyen de Belgique) Part II : Les Condylarthres
Jean Sudre and Donald E. Russell
Keywords: Belgium; Condylarths; Louisininae; Oxyclaeninae; Paleocene
 
  Abstract

    The Condylarths from Hainin (Hainault, Belgium) show no affinity at the generic level to those known in other Paleocene localities of Europe and North America ; they are described as new forms : Monshyus praevius n. gen., n. sp. and Prolatidens waudruae n. gen., n. sp. Monshyus praevius, discovered in only one of the levels in the excavation at Hainin, is similar to the genera Microhyus TEILHARD and Louisina RUSSELL ; with them it is included in the subfamily Louisininae (Hyopsodontidae). With respect to Microhyus and Louisina, Monshyus is distinguished by the precociously modern aspect of its upper molars, the only teeth that are referable. Prolatidens waudruae, known only by lower molars, was found in several levels in the pit at Hainin. It is an arctocyonid presenting possible relationships to the North American form Oxyprimus galadrielae ; it therefore has been provisionally attributed to the subfamily Oxyclaeninae. If this attribution is confirmed, this species will constitute the first and only representative of the group in Europe. 


  Article infos

Published in Vol. 12, Fasc. 6 (1982)

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Etude des dents jugales inférieures des Equus (Mammalia, Perissodactyla) actuels et fossiles
Véra Eisenmann
Keywords: Cheek teeth; Equus; Mammals
 
  Abstract

    The comparative morphology and biometry of the lower cheek teeth of modern Equus are studied on approximately 300 mandibles belonging to the 10 usually recognised species : Equus grevyi, E. burchelli, E. quagga, E. zebra, E. africanus, E. asinus, E. hemionus, E. klang, E. przewalskii, E. caballus. The studied parameters comprise : occlusal length and width, postflexid length and index ; shape of the double knot (metaconid + metastylid + lingual groove) ; depth of the vestibular groove on the molars ; frequency of the pli caballinid, protostylid and other enamel plications or islets ; frequency of the dP/l.
    The same methods of study are applied to a number of North American, Eurasian and African species. For the sake of comparison, some Hemphillian equids were observed (Dinohippus interpolatus, Dinohippus leidyanus, Astrohippus ansae, Phiohippus mexicanus) but most of the discussed material belongs to Pliocene or Pleistocene species of Equus : the « stenonine ›› E. stenonis, E. simplicidens, E. sanmeniensis and E. teilhardi; the « caballine ›› E. scotti, E. lambei, E. Iaurentius, E. mosbachensis, E. germanicus, E. gallicus, E. taubachensis and the Liakhov horse. The relationships of other species, in particular the North American E. calobatus, E. occidentalis, E. cf mexicanus are not clear for the moment. ln Africa, the Plio-Pleistocene species from Koobi Fora (Kenya) show some stenonine and perhaps asinine affinities. The relationships of E. numidicus and E. tabeti are uncertain but these species are probably related to the East African ones. E. mauritanicus is most certainly related to the Quagga group.
    The biometrical data are gathered in 32 tables ; 4 photographie plates and 19 figures illustrate the next. The whole is a complement of the previously published studies of the skulls, upper cheek teeth, incisors and metapodials of modern and fossil Equus.

      


  Article infos

Published in Vol. 10, Fasc. 3-4 (1981)

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Découverte d'un gisement de micromammifères d'âge Pliocène dans le bassin de Constantine (Algérie), présence d'un muridé nouveau : Paraethomys Athmeniae n.sp.
Brigitte Coiffait and Philippe-Emmanuel Coiffait
Keywords: Algeria; Constantine; Micromammals; Muridae; Pliocene
 
  Abstract

    The study of that locality allowed the description of a new Muridae : Paraethomys athmeniae n. sp. It reveals the existence of new rodent for Algeria : first, a Sciuridae, Atlantoxerus cf. rhodius, and second, a Gliridae, Eliomys truci. So, that work shows the presence of the genus Eliomys in North Africa before the middle of Pleistocene. Lastly, Paraethomys cf. anomalus gives an exact datation of that bed. 


  Article infos

Published in Vol. 11, Fasc. 1 (1981)

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Les sélaciens du Miocène de la région de Montpellier
Henri Cappetta
Keywords: Ichtyofauna; Miocene; Montpellier

doi: 10.18563/pv.3.ext.1-139
 
  Abstract

    The utilization of screen-washing and attack by dilute acetic acid has permitted the collecting, in the Miocene of the department of Hérault (France), of a very rich ichthyofauna. This fauna is presently comprised of about 60 studied species, of which 11 are new, and represents, in the present state of knowledge, the most varied Miocene selachian fauna described in the world.
    The abondance of material has allowed an overall revision to be made; it has thus been possible to complete the description and the figuration of species that were poorly known until now, and to synonymize species that were established on simple morphotypes. Paleo-ecologic study of the ichthyofauna has permitted conclusions to be drawn relative to climate and bathymetry; it was thus possible to show that the Miocene fauna of Hérault was a fauna of a subtropical sea, essentially neritic with rare pelagic contributions.
    Knowing the stratigraphic position of the localities, it has been possible to distinguish three faunal assemblages based on associations of species. Some hypotheses on the evolution of certain lineages have been expressed.
    The comparison of this fauna with that of other regions permitted the relationships of two diflerent faunal provinces to be specified: the first belongs to the northern domain, characterized by a fauna still subtropical but with numerous temperate water elements; the leoond belongs to the Mesogean domain characterized by warm water forms. It has also lhovm that contemporary faunas could be very different according to the bathymetric zone in which they lived, which furnishes valuable information for the paleogeographic reconstruction of sedimentary basins.
      


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Published in Vol. 3, Ext (1970)

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Carolocoutoia ferigoloi nov. and sp. (Protodidelphidae), a new Paleocene "opossum-like" marsupial from Brazil.
Francisco J. Goin, Edison V. Oliveira and Adriana M. Candela
Keywords: Brazil; Didelphimorphia; Itaborai; Marsupialia; New taxa; Paleocene; Protodidelphidae; South America
 
  Abstract

    Carolocoutoia ferigoloi gen. et sp. nov. is the largest of protodidelphid marsupials, known from Middle Paleocene levels at Itaboraí Formation, southeastern Brazil. It differs from other members of this family in having molars with low cusps which are basally inflated, rounded crests without cutting edges, and a thick enamel layer which is wrinkled, specially at the labial half. A comparative analysis among representatives of this family led us to recognize only three genera undoubtely assignable to it:  Protodidelphis PAULA COUTO, 1952, Robertbutleria MARSHALL, 1987, and Carolocoutoia gen. nov. Protodidelphids lack the basic derived features diagnostic of Polydolopimorphian marsupials, while most of its derived features agree with its belonging to the Didelphimorphia. Protodidelphids comprise a specialized clade of opossum-like marsupials adapted to frugivorous or frugivore-omnivorous feeding habits. They differ from other didelphimorphians in having very large, spire-like entoconids, reduced and antero-posteriorly compressed paraconids, absence of stylar cusp C and of para- and metaconules, large stylar cusps B and D which are proximate to each other, short postmetacristae, eccentric protocones, and molars that increase rapidly in size from M/ml to M/m3.
      


  Article infos

Published in Vol. 27, Fasc. 3-4 (1998)

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Le genre Leptolophus (Perissodactyla, Mammalia): morphologie et histologie dentaires, anatomie cranienne, implications fonctionnelles.
Jean-Albert Remy
Keywords: dental histology; Eocene; functional anatomy; Palaeotheriidae; skull anatomy; Southern France; Systematics
 
  Abstract

    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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