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Une faune du niveau d'Egerkinger (MP 14; Bartonien inférieur) dans les phosphorites du Quercy (Sud de la France)
Jean Sudre, Bernard Sigé, Jean-Albert Remy, Bernard Marandat, Jean-Louis Hartenberger, Marc Godinot and Jean-Yves Crochet
Keywords: Biochronology; Early Bartonian; Eocene; evolution; Mammals; New taxa; Quercy
 
  Abstract

    The Laprade fauna is chronologically situated between those from Egerkingen and Lissieu and consequently, is close to the MP 14 reference-level of the European mammalian biochronological scale (Symposium of Mainz, 1987).
    This new fauna is presently the oldest known in the Quercy phosphorites, formerly the Le Bretou fauna (MP 16) was considered as the oldest one. The Laprade fauna includes 21 species which belong in 7 mammalian orders (Marsupialia: Amphiperatherium bastbergense, Amphiperatherium goethei; Apatotheria: Heterohyus (Gervaisyus) pygmaeus nov. subgen., nov. sp.; Lipotyphla: Saturninia cf. mamertensis, Saturninia cf. intermedia; Chiroptera: Vespertiliavus lapradei nov. sp.; Rodentia: Protadelomys cf. lugdunensis, Elfomys nov. sp.; Primates: Nannopithex cf. filholi, cf. Pseudoloris or Pivetonia; Perissodactyla: ?Palaeotherium ?castrense, small-sized Palaeotherium sp., Plagiolophus sp., Anchilophus sp.; Artiodactyla: Dichobune cf. robertiana, Mouillacitherium cartieri, Tapirulus cf. depereti, Mixtotherium priscum, Pseudamphimeryx schlosseri, and Artiodactyla indet). Sixteen of these species are mentioned for the first time from the Quercy faunas.
    The recognition of a new apatemyid, Heterohyus (Gervaisyus) pygmaeus nov. subgen., nov. sp., attests to an early origin of a lineage known in the Late Eocene. The emballonurid bat Vespertiliavus lapradei nov. sp. is presently the earliest record of this genus and family. This Auversian fauna leads to discuss the age of taxa showing archaic features. These taxa were defined on specimens collected in the Quercy during the last century and have never been found in the Quercy localities recently investigated. This fauna bears also evidence of a karstic filling episode older than those previously dated by fossils in the Quercy Jurassic. 


  Article infos

Published in Vol. 20, Fasc. 1 (1990)

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La Poche à phosphate de Ste-Neboule (Lot) et sa faune de vertébres du Ludien Supérieur. 3- Chéloniens
France de Broin
Keywords: Eocene; Quercy Phosphorites
 
  Abstract

    The few remains recently collected at Ste Néboule (upper Eocene) belong to three genera: the Testudinid Ergilemys, of which it is the oldest occurence in Western Europa, probably Palaeochelys and an unpublished genus, which is peculiar to the Phosphorites du Quercy. Some statements are made on the chelonian fauna as a whole in that région. After the study of some characters proper to the genus Ergilemys, some remarks are made concerning its antecedents and descendants. 


  Article infos

Published in Vol. 08, Fasc. 2-4 (1978)

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Designating a lectotype for Mesacanthus pusillus (Gnathostomata: Acanthodii)
Matthew Baron and Kevin Seymour
Keywords: acanthodians; Chordata; Devonian; Midland Valley; Orcadian Basin

doi: 10.18563/pv.44.1.e2
 
  Abstract

    The early gnathostome genus Mesacanthus is well represented in both Lower Old Red Sandstone and Middle Old Red Sandstone assemblages of northern and central Scotland. This ‘acanthodian’ taxon is currently thought to comprise two valid species: M. mitchelli and M. pusillus. Although the whereabouts of the holotype of M. mitchelli (NHMUK PV P560) is known, the syntype material for M. pusillus has long been thought lost. Here we identify at least one specimen that formed part of the original syntype material for M. pusillus, albeit in a slightly different condition than when it was originally figured. This specimen is ROM 25872, which is here designated as the lectotype. A second specimen – ELGNM 1978.191.1 – could represent another of the syntype specimens, but poor preservation quality makes it impossible to be certain. 


  Article infos

Published in 44-1 (2021)

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S.I. Data
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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Nouvelles données sur les Ichnites de dinosaures d'El Bayadh (Crétacé Inférieur, Algérie)
Mostefa Bessedik, Cheikh Mammeri, Lahcene Belkebir, Mahammed Mahboubi, Mohamed Adaci, Hakim Hebib, Mustapha Bensalah, Bouhameur Mansour and Mohammed E. H. Mansouri
Keywords: Algeria; Brezina; El Bayadh; Ichnites; Lower Cretaceous; Sauropoids; Theropoids

doi: 10.18563/pv.36.1-4.7-35
 
  Abstract

    Evidence of 350 Lower Cretaceous Dinosaur footprints is pointed out in El Bayadh area. Their preliminary study allow to distinguish four trackway assemblages which reveal vertebrate bipedal presence forms of tri-and tetradactylous Dinosauroïds (Assemblages 1-3) and quadrupidal Sauropoïd (Assemblage 4).

    The analysis of their footprint biometric features will attribute the quadrupidal Sauropoïd form to Brontopodus ichnogenus which is weIl known in the Jurassic and Cretaceous periods. In retum and despite their age, the dinosauroïd forms were approached, temporarily, to Grallator and Eubrontes types.

    The occurrence of the dinosaur traces (Theropoïd and Sauropoïd) constitutes, in the Lower Cretaceous, an important first step of the knowlege of the marshy Reptilian fauna which takes over, from the begining of the Secondary Era, a wide paleogeographie area on the Southem Tethyan margin. 


  Article infos

Published in Vol. 36, Fasc. 1-4 (2008)

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Nouveaux gisements à rongeurs dans les molasses oligo-miocènes de la région toulousaine
Francis Duranthon
Keywords: Cricetidae; Eomyidae; GIiridae; Miocene; Oligocene; Rodents; Sciuridae; Southern France
 
  Abstract

    The fauna from three new rodent localities (Castelmaurou, Grépiac-carrière et Grépiac-rive gauche) from Oligo-Miocene molasses of the Toulouse area is described. The one from Colomiers is completed. 11 species belonging to 4 families (Cricetidae, Eomyidae, Gliridae, Sciuridae) are present. The Miocene localities of Grépiac-carrière and Colomiers are correlated with Balizac, La Brète, Lambert and Lespignan. Grépiac-rive gauche is just a little older than these sites. Castelmaurou is somewhat younger than La Milloque and belongs to Oligocene. 


  Article infos

Published in Vol. 22, Fasc. 2-3 (1993)

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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.

      


  Article infos

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. 7 - Les proboscidiens Deinotheriidae
Heinz Tobien
Keywords: allometry; Astaracian; Deinotherium; Montredon; Systematics; taphonomy; Vallesian
 
  Abstract

    Some complete tooth rows and about one hundred isolated teeth enabled the identification of the deinothere of the Vallesian site Montredon (Hérault) as Deinotherium giganteum KAUP 1829, mainly by comparisons with the likewise Vallesian sample of the type locality Eppelsheim (Rheinhessen, F.R.G.).
    Scatterdiagrams of the teeth show the importance of allometry during the phyletic size increase of the European deinotheres.
    Some taphonomic problems of the Montredon deinothere are briefly mentioned. 


  Article infos

Published in Vol. 18, Ext (1988)

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A new species of bat (Chiroptera: Vespertilionidae) from the early Oligocene global cooling period, Brule Formation, North Dakota, USA
Nicholas Czaplewski, Jeff Person, Clint Boyd and Robert Emry
Keywords: Eocene-Oligocene global cooling; Mammalia; Oligocene; Plecotini; Quinetia

doi: 10.18563/pv.42.2.e2
 
  Abstract

    We report the first confirmed fossil bats from North Dakota, including a new species referable to the Vespertilionidae represented by a maxilla with P4-M3 from the Brule Formation, Fitterer Ranch local fauna, early Oligocene, Whitneyan North American Land Mammal Age. Unassociated postcranial fragments of the humerus and femur also represent a vespertilionoid, but appear to reflect a different, unidentified species. The new taxon, Quinetia frigidaria sp. nov., is referred to the genus Quinetia, previously known only from approximately contemporaneous deposits in Europe. The new species is larger than Quinetia misonnei from the early Oligocene of Belgium. It is similar in some morphological characters to Chadronycteris rabenae (Chiroptera incertae sedis) of the late Eocene (Chadronian) of northwestern Nebraska and to Stehlinia species (?Palaeochiropterygidae) from the Eocene and Oligocene of Europe, but differs from each in morphological details of the dentition and maxilla. An unassociated talonid of a lower molar from Fitterer Ranch shows myotodont morphology, unlike the nyctalodont lower molars in Q. misonnei, and thus represents a second chiropteran taxon in the fauna. Quinetia frigidaria is a member of a Paleogene radiation of bats near the low point of the Eocene-early Oligocene decline in global temperatures, increased seasonal aridity, and loss of tropical floras from mid-latitude North America. 


  Article infos

Published in Vol 42-2 (2019)

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L'anatomie de Lyrocephaliscus euri (wiman), Trématosaure du Trias inférieur du Spitsberg : arrière-crâne, squelette axial et ceinture scapulaire.
Jean-Michel Mazin and Philippe Janvier
Keywords: skull anatomy; Spitsbergen; Trematosaurs; Trias
 
  Abstract

    The formic acid preparation of a nodule collected from the Lower Triassic of Spitsbergen, and containing a skull with some associated postcranial elements of Lyrocephaliscus euri (WIMAN), precises and enriches previous descriptions of the reputedly well-known trematosaur. lt permits more detailed descriptions of the occipital region, of the course of the carotid arteries and collateral vessels, and refutes the previous description of a stapedial foramen in trematosaurs. The discovery of pleurocentres associated with the other vertebral components confirms the primitive rhachitomy of trematosaurs. 


  Article infos

Published in Vol. 13, Fasc. 1-2 (1983)

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Table ronde sur les phosphorites du Quercy Montauban 15-16 Décembre 1972
Louis Thaler and Jean-Louis Hartenberger
Keywords: Quercy Phosphorites
 
  Abstract

    Voici une centaine d'années débutait sur les Causses du Quercy l'exploitation des phosphorites qui devait permettre d'amasser des collections de Vertébrés fossiles uniques au monde. Ces fossiles firent l'objet de nombreuses publications et les noms de Filhol, Gaudry, Schlosser, Stehlin, Teilhard de Chardin sont attachés à ces premières études.

    Après quelques années de prospection, les fouilles dans le Quercy ont repris en 1965, organisées par les laboratoires montpelliérains et parisiens. Ces premières recherches ont été aidées par le Centre National de la Recherche Scientifique qui a organisé une « table ronde» pour faire le point des premiers résultats obtenus. Ceux-ci ont été jugés suffisamment prometteurs pour que le C.N.R.S, ait décidé de poursuivre son effort par l'intermédiaire d'une Recherche Coopérative sur Programme.



      


  Article infos

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

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Sur le plus ancien Lagomorphe Européen et la "Grande Coupure" Oligocène de Stehlin
Nieves Lopez-Martinez and Louis Thaler
Keywords: Grande Coupure; Lagomorphe; Oligocene
 
  Abstract

    Pour la première fois un spécimen de lagomorphe a été récolté en Quercy. L'intérêt de ce fossile tient surtout à son âge géologique inattendu, qui recule considérablement la date de première apparition en Europe de cet ordre de mammifère, Ceci nous paraît justifier une nouvelle réflexion sur la « grande coupure» oligocène, 


  Article infos

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

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The Quaternary avifauna of Crete, Greece.
Peter D. Weesie
Keywords: Avifauna; Crete; Quaternary; Systematics
 
  Abstract

    Pleistocene bird fossils have been studied from nine localities on Crete. Part of this material was described earlier by the author (Weesie, 1982) and will not be treated here in extenso, the results will be incorporated. More than one third of the over 10,000 fossil bird bones available could be identified ; they were found to represent at least 65 bird species. The following species of the Pleistocene Cretan avifauna are new to the fauna of Crete : Branta ruficollis, Haliaeetus albicilla, Gyps melitensis, Aquila chrysaetos simurgh n. ssp., Ketupa zeylomensis, Aegolius funereus, Dendrocopos leucotos, Zoothera dauma, Turdus iliacus and Pyrrhula pyrrhula. The Pleistocene Cretan avifauna differs less from comparable mainland avifaunas than (fossil) avifaunas from oceanic islands do. Still, the Pleistocene Cretan avifauna has two qualities that are characteristic of island avifaunas : the almost complete absence of a group of birds (the Galliformes) and the presence of two endemic (sub)species : the giant eagle Aquila chrysaetos simurgh n. ssp. and the long-legged owl Athene cretensis (Weesie, 1982). The new subspecies is described in the present study.
    These endemic birds of prey were found in association with their supposedly principal prey species (now extinct as well) : endemic mice for the owl and endemic deer for the eagle. Endemic mammals have been found in association with endemic birds of prey on many islands, not only in the Mediterranean. There is evidence that the size of endemic birds of prey becomes optimally adapted to their feeding on certain endemic mammals, especially rodents. Another characteristic of the Pleistocene Cretan avifauna is the great number of species of birds of prey. This appears to be a common characteristic of fossil avifaunas from caves on Mediterranean islands as well as from caves on the European mainland. However, we think that ecological conditions on Pleistocene Crete (especially the abundant presence of mice) helped to account for the high representation of birds of prey. Furthemore, the fossil avifauna enables us to draw some conclusions about the climate and vegetation on Pleistocene Crete : it is concluded that the climate was cooler than today and that Crete was largely covered with forests. Finally, the reasons for the extinction or disappearance from Crete of some bird species of the Pleistocene Cretan avifauna are discussed. 


  Article infos

Published in Vol. 18, Fasc. 1 (1988)

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Les Palaeotheridae (Perissodactyla) de la faune de Mammifères de Fons 1 (Eocène supérieur).
Jean-Albert Remy
Keywords: Anchilophus; Eocene; Pachynolophus; Palaeotheriidae; Perissodactyla

doi: 10.18563/pv.1.1.1-46
 
  Abstract

    The locality of Fons 1, one of the fossiliferous outcrops in the late Eocene limestones of Fons-outre-Gardon (Gard), has yielded varied remains of mammals. The specimens were prepared by dilute acetic acid attack on the rock and by impregnation with an acrylic resin.
    This fauna, rich with about 20 species, can be included in the biochronologic zone of Euzet. The Palaeotheridae (sensu Simpson 1945), represented by 6 species, occupy a predominant place; Plagiolophus annectens is particularly abundant, comprising 55% of all the specimens found.
    The abundance of this species has permitted a detailed comparative study with the corresponding form from Euzet. The quantitative tests brought out a slight but highly sígnificant difference between the average dimensions of the teeth in the two populations. Moreover and in spite of the feeble rate of evolution in the Plagialophus dentition, diverse archaic particularities can be seen which permit the conclusion that the form from Fons 1 is a little the older. This conclusion is corroborated by observations on the other palaeotherids, particularly Lophiotherium aff. cervulum, whose dental evolutionary stage is intermediate between those of the corresponding forms known from Robiac and Euzet.
    A new species of Pachynolophus is described, P. garimondi n.sp., the last representative known of the genus. lts teeth are distinguished by their size, a great heterodonty, and the weakness
    of their cingula. 


  Article infos

Published in Vol. 01, Fasc. 1 (1967)

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Two new scyliorhinid shark species (Elasmobranchii, Carcharhiniformes, Scyliorhinidae), from the Sülstorf Beds (Chattian, Late Oligocene) of the southeastern North Sea Basin, northern Germany.
Thomas Reinecke
Keywords: Chattian; Elasmobranchii; North Sea Basin; Scyliorhinidae; Scyliorhinus

doi: 10.18563/pv.38.1.e1
 
  Abstract

    Based on isolated teeth two new scyliorhinid shark species, Scyliorhinus biformis nov. sp. and Scyliorhinus suelstorfensis nov. sp., are described from the Sülstorf Beds, early-middle Chattian, of Mecklenburg, northeastern Germany. They form part of a speciose assemblage of necto-benthic sharks and batoids which populated the warm-temperate to subtropical upper shelf sea of the south-eastern North Sea Basin. 


  Article infos

Published in Vol.38-1 (2014)

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Artiodactyla aus den Eozänen Braunkohlen des Geiseltales bei Halle (DDR)
Jorg Erfurt and Hartmut Haubold
Keywords: Artiodactyles; Eocene; Europe; Paleoecology; Stratigraphy; taxonomy
 
  Abstract

    The present study of Artiodactyla from the Middle Eocene of the Geiseltal lignite beds concems systematics, biostratigraphy, and palaeoecology on the basis of 174 specimens: isolated remains to more complete skeletons. Instead of the formerly known five species of two families are now recognized 14 species of the Diacodexeidae, Dichobunidae, Cebochoeridae, and Haplobunodontidae. New species are Aumelasia maniai, Anthracobunodon neumarkensis, Masillabune franzeni. Four species of the Geiseltalfauna are definitely known from elswere, and five species are closely related to those from other European localities. Evidently the faunal situation of artiodactyls during the Middle Eocene of Europe was largely uniform. The distribution of artiodactyls within the sequence of the Geiseltal strata corroborates the biostratigraphical concept of the land mammal age Geiseltalian (Franzen & Haubold l986b) as well as the mammalian reference levels MP 11-13 (Franzen 1987). Reconstructions of the skulls and skeletons allow conclusions on the functional morphology and palaeoecology of the artiodactyls of the European Middle Eocene 


  Article infos

Published in Vol. 19, Fasc. 3 (1989)

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Morphological description and identification of an extraordinary new elephant cranium from the early Pliocene of Ileret, Kenya
 
William Sanders, Meave Leakey, Louise Leakey, Craig Feibel, Timothy Gichunge Ibui, Cyprian Nyete, Mbatha P. Mbete and Francis Brown
Keywords: Elephantidae; Loxodonta adaurora; cranium; early Pliocene; Ileret; Kenya

doi: 10.18563/pv.44.2.e3
 
  Abstract

    Abstract: Paleontological exploration in the Turkana Basin near Ileret, Kenya yielded the most complete adult elephant cranium (KNM-ER 63642) known from the late Miocene to mid-Pliocene. KNM-ER 63642 derives from the lower Lonyumun Mb. of the Koobi Fora Fm. and dates to the early Pliocene, >4.3 Ma. The cranium is immense in size and preserves most of its structures including left and right M2-3, permitting its comprehensive comparative study and secure taxonomic assignment to Loxodonta adaurora. Features distinctive of the species and exhibited by KNM-ER 63642 include very elongate, divergent tusk alveoli, a short, biconvex cranial roof, anterosuperior angulation of the occipital planum, non-inflated occipital planum and absence of supralateral parietal "bossing," broad, flat premaxillary nasal processes, broad, laterally downturned nasal aperture superior to the level of the orbits, and M3s with wide, subhypsodont plates that are parallel-faced and separated by U-shaped transverse valleys. The M3s also exhibit characteristic L. adaurora traits of greatest width at their bases, rounded cross-sectional shape, thick enamel, abundant cementum, and strong anterior and posterior accessory conules. Of extant taxa, KNM-ER 63642 most closely resembles crania of African elephants. Its inclusion in the Loxodonta clade is tenuous, however, because shared features are either symplesiomorphic or are difficult to test for synapomorphy due to the poor fossil record of crania of late Miocene-early Pliocene elephants. Overall, the cranial morphology of KNM-ER 63642 is unexpectedly advanced for an elephant of its antiquity. Its anteroposterior compression and height are concordant with efficient proal masticatory action, indicating that by the early Pliocene L. adaurora evolved craniodental adaptations in phase with feeding preference for C4 grasses. The advantage of synchrony of morphology and behavior is reflected by the dominance of the species in the greater Turkana Basin during that interval.
      


  Article infos

Published in 44-2 (2021)

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Rongeurs nouveaux de l'Oligocène Moyen d'Espagne.
Louis Thaler
Keywords: Cricetidae; Oligocene; Pseudocricetodon; Rodents; Theridomys

doi: 10.18563/pv.2.5.191-207
 
  Abstract

    Description of four new rodents from a recently discovered locality at Montalban. Theridomys crusafonti nov. sp. is considered as the ancestry of T. Iembronicus. Theridomys varian: nov. sp. includes «Theridomys» morphotypes and «Blainvilllimys» morphotypes; it could be ancestral to B. blainvillei. Pseudoltinomys nanus nov. sp. represents a new lineage paralleling in evolution that of P. gaillardi (which is equally found at Montalban). Pseudocricetodon montalbanensis nov. gen., nov. sp. designates a lineage of very small Cricetidae accompanying Eucricetodon. With these well defined new species and six others present in the locality, Montalban appears as the best faunal reference point within the biochronologic zone of La Sauvetat.
    As an annex, discussion of two rodent specimens from the classic localíty of Tárrega, close in age to that of Montalban. 


  Article infos

Published in Vol. 02, Fasc. 5 (1969)

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Le genre Plagiolophus (Palaeotheriidae, Perissodactyla, Mammalia): révision systématique, morphologie et histologie dentaires, anatomie crânienne, essai d'interprétation fonctionnelle
Jean-Albert Remy
Keywords: New taxa; Paléogène; perissodactyls; skull anatomy; tooth histology
 
  Abstract

    The genus Plagiolophus is documented, almost solely in Western Europe, from the middle Eocene up to the mid Oligocene (MP 12 to MP 25), i.e. more than for 15 MY. Seventeen species are now recorded whose two of them are new, P. ringeadei nov. sp. and P. mamertensis nov. sp. Some anatomical variations and the deflection of certain evolutionary trends justify the distinction of three subgenera, Paloplotherium, Fraasiolophus nov. and Plagiolophus s.s. The genus displays a wide range in size and weight (between 10 and 150 kg). The detailed description of the skull of several species is here given for the first time.
    Despite important evolutionary drifts during this long time span, the dentition shows a great structural homogeneity, which renders difficult the determination of fragmentary specimens or isolated teeth. It is characterized by a great heterodonty; premolars are little molarized and present a certain regression through time with paradoxically some progress in the molarization. The hypsodonty increases: the first Plagiolophus are hardly less brachyodont than Propalaeotherium, and the last ones are nearly as hypsodont as Merychippus from the early Miocene. The upper molars change from a wide crown pattern, with an open occlusal surface, lightly oblique transverse lophs and rounded internal cusps, to a narrower pattern, with a frontally constricted occlusal surface and internal lophs aligned parallel to the ectoloph. The M3/3 become always longer.

    The dental enamel displays horizontal Schreger-bands with imprecise limits occupying only the middle part of the enamel layer. The dentine is remarkable by its high rate of pericanalicular dentine. The crown cementum, lacking in earlier forms, increases to the point where it fills the occlusal valleys of the
    teeth.

    The masticatory musculature shows a increasing prominence of the temporal, with probably an important role devoted to the pterygoid muscles in lateral movements related to a two-phase type of chewing.

    The evolution of the dentition, of the masticatory musculature and of the repartition of masticatory forces indicate that the Plagiolophus have known different diets through their long evolutionary history; at first browsers they became mixed feeders and finally grazers. Their relatively long neck allowed these animals to reach different vegetal layers. The strength of the nuchal crests also suggests that they were able to have strong backwards movements of the head to pull up their food.

    This evolution of diet seems related to the slow degradation of environmental conditions attested during this period in western Europe, with the generalization of more open landscapes, increasing aridity and more marked seasons.

    Besides, a remodeling of the face is ontogenetically and along time observed, in relation with the evolution of the masticatory apparatus and especially with that of the mandibular lever arm. The postcanine diastemata become longer in the course of evolution; the free extremities of the nasals are always relatively long which contradicts the hypothesis according to which Paloplotherium may have had a trunk. At last the lineage Fraasiolophus can be distinguished by the presence of a deep malar fossa, probably related to a strong development of the maxillo-labialis superior muscle.

    The orbit is always large and tends to increase in size, which indicates a good development of the vision and its increasing role in the life relations. A peculiar type of epitympanic sinus could have been used as a resonance chamber insuring a certain amplification of sounds before their transmission to the eardrum. The endocranial cast reveals a relatively large brain with an advanced degree of gyrencephaly. Beside the role eventually played in food research and social relations, these neurophysiological abilities, also related to an advance in cursorial fitness, could have contributed to the survival of these animals facing the predation pressure of the first fissipede carnivores and the competition with new immigrant herbivores after the "Grande Coupure".
    On the basis of some shared apomorphies with the Pachynolophinae, which prevent from considering the latter as Equidae (molarization of the premolars, reduction of the premaxilla dorsal apophysis, peculiar epitympanic sinus, splitting of the jugular process), the hypothesis of an autochthonous origin of Plagiolophus issued from a form near Propalaeotherium, is once again proposed and discussed. Finally, intra-generic relationships are taken into consideration. 


  Article infos

Published in Vol. 33, Fasc. 1-4 (2004)

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Eurodexeinae, eine neue unterfamilie der Artiodactyla (Mammalia) aus dem unter- und mitteleozän europas
Jorg Erfurt and Jean Sudre
Keywords: Artiodactyls; Eocene; evolution; Germany; Lutetian; new genus; New subfamily
 
  Abstract

    Dichobunoid artiodactyls are described in this paper from the middle Eocene Geiseltal lignite deposits near Halle (Sachsen-Anhalt, Germany). The genera Eurodexis and Parahexacodus are established based on odontologica1 studies. The type-species are E. ceciliensis (FRANZEN & KRUMBIEGEL, 1981) and P. germanicus n. sp. from the "obere Mittelkohle" (see text), MP 13. The genera are referred to the new subfamily Eurodexeinae (Dichobunidae, Artiodactyla, Mammalia), which also contains the monospecific genus Eygalayodon SUDRE & MARANDAT, 1993. These new genera show many features similar to North American homacodontids and antiacodontids. They exemplify a high degree of diversity in European dichobunids. Moreover, the family Dichobunidae includes the Dichobuninae and the Hyperdichobuninae. The connection of the posthypocristid with the postentocristid, the shift of a medial to a lingual position of the hypoconulid on the lower molars and the development of a large, caniniform P1 are regarded as the principal tendencies of the eurodexeines. The entoconid is larger and more mesially situated compared to that of Diacodexis. The hypoconulid has a lingual position on a broad postcingulid. The elongation of the premolars and the presence of diastemata are considered associated with extension of the muzzle. This and the acute tubercles of the molars could indicate a limited degree of insectivory. Protodichobune cf. oweni and Diacodexis cf. varleli, first reported here from the "untere Unterkohle" (MP 11) of the Geiseltal, demonstrate the existence of forms in the basal part of the middle Eocene, that are direct descendants of lower Eocene ones. Eurodexis russelli n. sp. from MP 10 of Premontre is the most primitive representative of Eurodexis. A further part of this lineage could be Messelobunodon sp. from MP 11 of Messel (Germany). Another form from Premontre, referred to Eurodexeinae indet., represents the origin of the lineage to Parahexacodus germanicus n. sp. from the Geiseltal (MP 13). The identification of several lineages in MP 10 is evidence of an adaptive radiation during this time. Unfortunately the history of the earlier species of Diacodexis is not known well enough to exclude earlier diversifications. Our study shows the independent development of artiodactyls at the end of the lower Eocene in Europe, North America (and maybe in Asia) with much convergence. The question of the geographic origin of the genus Diacodexis is still open. 


  Article infos

Published in Vol. 25, Fasc. 2-4 (1996)

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