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Révision des Rhombodontidae (Neoselachii Batomorphii) des bassins à phosphate du Maroc
Abdelmajid Noubhani and Henri Cappetta
Keywords: Batomorphii; Maastrichtian; Morocco; New taxa; Phosphate; Rbombodontidae
 
  Abstract

    The revision of the Rhombodontidae from the Maastrichtian of Morocco led us to the description of a new species: Rhombodus andriesi.

    The biometrical study of populations of R. binkhorsti and R. microdon, species sometimes considered as synonymous, supports the conclusion that they represent two distinct species and not young and adult specimens of a single species. The stratigraphical range of these two species confirms this
    result.

    The reexarnination of type-series studied by C. Ararnbourg led us to revise the generic status of Rhombodus bondoni which is now ranged, because his dental features, in the new genus Dasyrhombodus showing a less derived dentition than Rhombodus. The stratigraphical range of each species is clarified within the phosphatic series. 


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

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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 Lehmann
Keywords: Oligocene; Pangolin; Pech du Fraysse; Quercy phosphorites

doi: 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. 



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Published in Vol.39-2 (2015)

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The skull of Tetraceratops insignis (Synapsida, Sphenacodontia)
Frederik Spindler
Keywords: cranium; pelycosaur; Permian; therapsid origins

doi: 10.18563/pv.43.1.e1
 
  Abstract

    Tetraceratops insignis is known from a single, crushed skull from the Lower Permian of Texas. Its unique proportions and osteological details gained central meaning in the question of the origins of Therapsida since this early synapsid has been determined as the oldest and less derived therapsid. Apart from Tetraceratops, the ‘mammal-like’ Therapsida and their sister, the pelycosaur-grade Sphenacodontidae, are separated by one of the longest ghost lineages in tetrapod fossil record. However, the minor, though well justified critique faced insistent publication regarding the therapsid hypothesis. A carefull re-evaluation of the holotypic skull reveals that therapsid traits cannot be supported, including a rejection of the formerly supposed adductor shelf in the temporal fenestra. Increased understanding of ‘pelycosaur’ character variation underlines a haptodontine-grade or, less likely, sphenacodontid position for Tetraceratops


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Published in Vol 43-1 (2020)

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Les traces de pas de Dinosaures et autres Archosaures du Lias inférieur des grands Causses, Sud de la France
Georges Demathieu, Georges Gand, Jacques Sciau, Pierre Freytet and Jacques Garric
Keywords: Dinosauroid footprints; France; Grands-Causses; Hettangian; ichnostratigraphy; paleoenvironments; Sinemurian; statistical results

doi: 10.18563/pv.31.1-4.1-143
 
  Abstract

    The Causses" is a near 3400 km2 large plateau located in the south of France. Here the first dinosaur footprints where found in 1935. After this, this area has yielded an ever-increasing number of ichnites now in excess of 500 specimens. These latter, 15 to 50 cm long, tridactyl or tetradactyl footprints of generally biped animals, were discovered at the surface of Hettangian to lower Sinemurian dolomite layers within 4 distinct stratigraphic units. The 35 sites bearing ichnites are located on the plateau margin. For the first time, morphologic characters studied through descriptive statistic methods with the usual parameters and classical Student and Snédecor tests, allowed us, to divide the whole set of biped traces into 6 ichnospecies. Their definitions are further constrained by multivariate statistical results using Principal Component Analysis (PCA), Factor Analysis of correspondances (FAC) and Discriminant Analysis (DA). All have confirmed the morphologic observations. So that now, the following taxa are identified : Grallator variabilis, G. lescurei, G. sauclierensis, G. minusculus, Eubrontes giganteus, Dilophosauripus williamsi, cf. Moraesichnium, Orníthopus fabrei nov ichnosp. The more immediately visible differences relate to the interdigital II-IV divarication and the digit length ratio. To this panel, we must add Batrachopus deweyi and shapes suggesting Trisauropodichnus and/or Anomoepus. Among all ichnite associations described in the lower Liasic, the New England assemblage presents the most affinities with ours. It shows the ichnotaxa Grallator, Dilophosauripus, Eubrontes, Batrachopus without forgetting Ornithopus fabrei nov. ichnosp. which is close to Ornithopus gallinaceus from the Massachusetts and Connecticut basins. On comparing the present early Jurassic ichnofauna of the Causses with the ones of the Middle and Upper Triassic formations of the eastem border of the Massif Central (France), it appears that tridactyl footprints become more and more numerous and large from Triassic to Early Jurassic. In the Causses, these latest are prevalent but in Quercy (France), Poland, Italy, USA, they are also associated with Omithopoda, Thyreophora and Sauropoda ichnites. Footprint areas considered here were generaly under an arid climate. Animals that passed by were heavy and bulky possible Megalosaur trackmakers, and lighter and slender Coelophysids or Ceratosaurs. For all, these areas were pathways as the orientations of the trackways seem point out. The directions followed by these reptiles were without any important variation during the Hettango-Sinemurian stages. These areas were also used from time to time by Crocodilomorpha and may be tetradactyl (I-IV) bipedal avian Theropods. However, the number of such trackways in sites, sometimes substantial, should not lead us to overestimate the trackmakers populations. These last were probably relatively moderately abondant in this inter-supratidal swamp environment. In the Causses, ichnites are connected with former algo-laminated deposits (Algal mats) which were rapidly hardened by means of calcitisation of cyanobacteria. The result has been a moderate depth of footprints; autopodia disturbing only a few cm of the carbonate substrate. Other fossils have been discovered : invertebrates with thin bivalve and gastropod shells, crustaceans tests and plants. These latter suggest the existence of paleomangroves like environments but also continental vegetation periodically overruning the swamp environment during regression/transgression cycles. At these times, wooded parts of it, could become protecting, feeding, resting and nesting places.

      


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Published in Vol. 31, Fasc. 1-4 (2002)

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There were giants upon the earth in those days
Pierre-Olivier Antoine
Keywords: Eurasia; history of science; Indricotheriinae; Paleogene; Rhinocerotoidea

doi: 10.18563/pv.38.1.e4
 
  Abstract

    Rhinoceros Giants: the Paleobiology of Indricotheres. Donald R. Prothero. Life of the Past Collection, Indiana University Press; 160 pp. (66 b&w illustrations). Hardback (7x10”): USD 42.00 plus shipping. ISBN: 978-0-253-00819-0. E-book: USD 34.99. ISBN: 978-0-253-00826-8.
      


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Published in Vol.38-1 (2014)

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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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A new and primitive species of Protophiomys (Rodentia, Hystricognathi) from the late middle Eocene of Djebel el Kébar, Central Tunisia
Laurent Marivaux, El M. Essid, Wissem Marzougui, Hayet Khayati Ammar, Sylvain Adnet, Bernard Marandat, Gilles Merzeraud, Rodolphe Tabuce and Monique Vianey-Liaud
Keywords: Adaptive radiation; Bartonian; Dental morphology; North Africa; Paleobiogeography

doi: 10.18563/pv.38.1.e2
 
  Abstract

    Based on fossil discoveries and phylogenetic studies, an Eocene Asian origin for hystricognathous rodents and anthropoid primates has gained strong support in recent years. The two groups then invaded both Africa and South America, which promoted their evolutionary success. However, the fossil record has so far failed to constrain the nature and precise timing of these pivotal dispersal events. In Africa, given the apparent absence of hystricognaths and anthropoids in early to early middle Eocene localities, it is suggested that these mammal groups dispersed from Asia to Africa sometime during the middle Eocene. In this paper, we report the discovery of several isolated teeth of a rodent from a new vertebrate locality situated in central Tunisia (Djebel el Kébar, KEB-1), dating from the late middle Eocene (Bartonian, ~39.5 Myr). These fossils document a diminutive new species of Protophiomys (P. tunisiensis nov. sp.), a basal genus of hystricognathous rodents which is well known from several North African mammalian-bearing localities of the end of the Eocene. The teeth of P. tunisiensis display a suite of anatomical details comparable with those observed in the other species of the genus, but with a lesser degree of development. Such an apparent primitive evolutionary stage is corroborated by the greater antiquity of this Tunisian species. P. tunisiensis nov. sp. is so far the most ancient representative of hystricognaths in Africa. However, it can be expected that hystricognaths were already present on that landmass given the new data on early caviomorphs recently reported from South America (at ~41 Myr). The arrival of hystricognaths in Africa from South Asia certainly predates the depositional period of the Kébar sediments, but perhaps not by much time. 


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Published in Vol.38-1 (2014)

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La palichnofaune de vertébrés tétrapodes du permien supérieur du Bassin de Lodève (Languedoc-France).
Georges Gand, Jacques Garric, Georges Demathieu and Paul Ellenberger
Keywords: Footprints; France; Languedoc; Lodève basin; new ichnotypus; Saxonian; Upper Permian
 
  Abstract

    Near "la Lieude", in the Lodève basin, more than a thousand of footprints are distributed in a twenty of trackways which amounts to 220 m length. They have been found on calcareous siltstone level in the B site named also "Réserve Naturelle Volontaire". This last is located in the Saxonian summit dated Upper Permian. "La Lieude" tracks are described by using statistical methods then they are compared with others from the world Permian. What allows to distinguish 4 following ichnotaxa: Lunaepes ollierorum nov.ichnosp., Merifontichnus thalerius nov. ichnogen. and nov. ichnosp., Planipes brachydactylus nov.ichnosp. and Brontopus circagiganteus nov. ichnosp. All these traces are attributed with possibility or probability to Therapsida or to Therosauria, except Brontopus circagiganteus nov. ichnosp. that could be due to Caseamorpha. All these animals whose sizes have been estimated between l and 5 m lived probably in a playa environment.The biological and sedimentological data from "la Lieude" footprints levels compared with informations provided by the tracks orientations, suggest the following scenario. Animals coming from the North have crossed a sandy channel bank with plants zones by directing to the South for the majority. Maybe, they were going to the lacustrine part of the playa, close to "la Lieude" footprints that they have just trampled on. 


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Published in Vol. 29, Fasc. 1 (2000)

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Evolution et extinction des reptiles marins au cours du Mésozoïque.
Nathalie Bardet
Keywords: Crocodiles; evolution; Extinctions; faunal assemblages; Helveticosaurs; Hupehsuchians; Ichthyoaurs; lizards; Marine Reptiles; Mesozoic; Nothosaurs; Pachypleurosaurs; Placodonts; Plesiosaurs; Snakes; Thalattosaurs; Turnovers; Turtles
 
  Abstract

    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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Les Périssodactyles (Mammalia) du gisement Bartonien supérieur de Robiac (Éocène moyen du Gard, Sud de la France)
Jean-Albert Remy
Keywords: Chasmotherium; new species; Palaeotheriidae; paleoenvironments

doi: 10.18563/pv.39.1.e3
 
  Abstract

    We present here a new updated counting of the perissodactyls of Robiac, the type locality of the MP 16 level of the biochronological scale of paleogene mammals and that of the Robiacian stage of Eocene Land Mammals Ages in Western Europe.
    The outcrop of Robiac consists actually of two 500m apart loci, Robiac-Nord and Robiac-Sud, considered of the same age according to the current discriminating power, and is dated from -38,7 MA after the last faunal, magnetostratigraphic and climatic calibrations.
    It has yielded a very abundant and rich of 21 taxa perissodactyl fauna, topped by the giant Lophiodon lautricense, last representative of the family Lophiodontidae, of which it is the last proved deposit. The Palaeotheriidae are much diversified with 5 genera and 9 species of "Pachynolophinae", 3 genera and 10 species of Palaeotheriinae. Nine taxa have been defined from Robiac: Chasmotherium depereti n. sp., Palaeotherium castrense robiacense Franzen, 1968, the genus Leptolophus Remy, 1965 with the species L. stehlini Remy, 1965 and L. magnus Remy, 1998, Anchilophus (Paranchilophus) jeanteti Remy, 2012, Metanchilophus chaubeti Remy, 2012, Lophiotherium robiacense Depéret, 1917 and Pachynolophus gaytei n. sp.
    The faunal Robiac cenogram with the associated flora testify to a hot, wet and forestal environment, likely corresponding to a short warming climatic phase; the broken up fossil bones should have been carried away and then gathered in swamp areas along the banks of a meandering river.
    The swarm of mammals of Robiac, the richest of contemporaneous deposits, has been followed by a drastic drop in perissodactyl diversity at the MP 17A level; a crisis which could have originated in a renewal of the global Eocene cooling. Fons 4, the type-locality of this level, is largely scarcer in perissodactyls and its cenogram testifies to a less diversified fauna, with on the whole smaller species, that likely means a cooler and drier climatic environment; a new perissodactyl diversification occurred but later.
      


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Published in Vol.39-1 (2015)

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Macroscelidea, Insectivora and Chiroptera from the Miocene of east Africa.
Percy M. Butler
Keywords: Chiroptera; East Africa; Insectivora; Macroscelidea; Miocene; systematics
 
  Abstract

    The East African Miocene Macroscelidea, lnsectivora and Chiroptera are revised on the basis of new material. New taxa proposed are: Miorhynchocyon, .n. gen. (Macroscelididae): Míorhynchocyon meswae, n. sp.: Pronasílío ternanensis. n. gen.. n. sp. (Macroscelididae); Hiwegicyon juvenalis, n. gen. n. sp. (Macroscelididae); Parageogale, n. gen. (Tenrecidae): Prochrysochlorinae, n. subfam. (Chrysochloridae): Propottininae, n. subfam, (Pteropodidae); Chamtwaria pickfordi, n. gen., n. sp. (Vespertilionidae). Gymnurechnínus songhorensis is synonymised with G. camptolophus. The new material provides additional information on the dentition, especially of Myohyrax oswaldi. Galerix africanus. Amphechínus rusingensis, Protenrec tricuspis and Parageogale aletris. Partial skulls are described of Amphechinus rusingensis, Protenrec tricuspis, Prochrysochloris míocaenicus and Taphozous incognita. The oldest member of the Macroscelidinae (Pronasilio) is described from Fort Ternan. Galerix africanus is closely related to G. exilis from Europe. Amphechinus rusingenesis is compared with Asiatic Oligocene Erinaceinae. The Miocene age of Crocidura is rejected. On the evidence of humeri, the following families of Chiroptera are newly reported: Pteropodidae, Nycterididae, Vespertilionidae, Molossidae. Propotto is regarded as an offshoot from the Pteropodidae, not ancestral to modern forms. Chamtwaria is a primitive vespertilionoid, provisionally placed in the Kerivoulinae. Erinaceidae probably entered Africa at the beginning of the Miocene, before 20 Ma. Faunistic differences between deposits are largely to be ascribed to differences in local environment. 


  Article infos

Published in Vol. 14, Fasc. 3 (1984)

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Batoids (Rajiformes, Torpediniformes, Myliobatiformes) from the Sülstorf Beds (Chattian, Late Oligocene) of Mecklenburg, northeastern Germany: a revision and description of three new species
Thomas Reinecke
Keywords: Batoids; Chattian; Elasmobranchii; North Sea Basin; Oligocene

doi: 10.18563/pv.39.2.e2
 
  Abstract

    Bulk-sampling of fossil-rich tempestites from the Chattian Sülstorf Beds of
    Mecklenburg, north-eastern Germany, yielded a rich selachian fauna in which batoids
    predominate by the abundance of teeth but are subordinate by the number of taxa. Thirteen
    taxa are identified, among which rajiform batoids are the most diverse (six species). One
    genus and three species are newly described: Raja thiedei sp. nov., Oligoraja pristina gen. et
    sp. nov., and Torpedo chattica sp. nov. Two species are reallocated: Atlantoraja cecilae
    (Steurbaut & Herman, 1978) new comb., and Dipturus casieri (Steurbaut & Herman, 1978)
    new comb. Ontogenetic heterodonty is documented for the first time in the dental pattern of
    Myliobatis sp. Stratigraphical ranges of batoid taxa in the period from Rupelian to Langhian
    are presented and partly discussed in context with the palaeoclimatic evolution and
    palaeogeographic situation of the North Sea Basin. 


  Article infos

Published in Vol.39-2 (2015)

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Latest Early-early Middle Eocene deposits of Algeria (Glib Zegdou, HGL50), yield the richest and most diverse fauna of amphibians and squamate reptiles from the Palaeogene of Africa
Jean-Claude Rage, Mohamed Adaci, Mustapha Bensalah, Mahammed Mahboubi, Laurent Marivaux, Fateh Mebrouk and Rodolphe Tabuce
Keywords: Africa; Algeria; amphibians; Eocene; squamates

doi: 10.18563/pv.43.2.e2
 
  Abstract

    HGL50 is a latest Early-early Middle Eocene vertebrate-bearing locality located in Western Algeria. It has produced the richest and most diverse fauna of amphibians and squamate reptiles reported from the Palaeogene of Africa. Moreover, it is one of the rare faunas including amphibians and squamates known from the period of isolation of Africa. The assemblage comprises 17 to 20 taxa (one gymnophionan, one probable caudate, three to six anurans, seven ‘lizards’, and five snakes). Two new taxa were recovered: the anuran Rocekophryne ornata gen. et sp. nov. and the snake Afrotortrix draaensis gen. et sp. nov. The locality has also yielded the first confirmed anilioid snake, the first Palaeogene gymnophionan, and probably the first caudate from the Palaeogene (and possibly from the Tertiary) of Africa. The presence of a caudate at that time in Africa would be of particular interest; unfortunately, the available material does not permit a definitive identification. The fauna comprises Gondwanan and more specifically West Gondwanan vicariants, probably autochthonous groups and a Eurasian immigrant (assuming that the identification of the caudate is accurate). The fauna from HGL50 is clearly distinguished from the few other Eocene assemblages of Africa. However, if this results largely from differences in geological ages, geographic positions of the localities and mainly differences in environments took a part in the composition of the faunas. 


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Analysis of changing diversity patterns in Cenozoic land mammal age faunas, South America
Larry G. Marshall and Richard L. Cifelli
Keywords: Cenozoic; Chronofaunas; diversity; Equilibrium theory; Extinction; Land mammal faunas; Origination; South America
 
  Abstract

    Comparison of various measurements of taxonomic evolution using stratigraphic range data for orders, families and genera of land mammals indicates several means by which deficiencies of the South American fossil record (e.g., presence of hiatuses, unequal temporal and geographic representation of ages, unequal systematic treatment) may be normalized, thus permitting a less distorted appreciation of diversity pattern and trend. Initial radiation of native taxa resulted in a relative equilibrium by early Eocene time. Subsequent increases in absolute diversity were apparently induced by immigration at the family level and by environmental factors at the generic level. Miocene through Pleistocene phases of faunal stability, herein characterized as chronofaunas, are punctuated by rapid turnover events resulting from a complex of factors, including adaptive radiation of immigrant taxa into unoccupied eco-space; environmental and concomitant habitat change induced by orogenic events of the Andes; and biotic interactions between native and immigrant taxa, including competition and prey naivete. The first two factors account for major faunal transitions in the South American middle and late Tertiary; immigration-induced turnover may have been of greater importance in shaping the character of the fauna upon the Great American Interchange and the arrival of man in the Neotropics 


  Article infos

Published in Vol. 19, Fasc. 4 (1990)

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Sur les empreintes de pas des gros mammifères de l'Eocène supérieur de Garrigues-ste-Eulalie (Gard)
Paul Ellenberger
Keywords: Eocene; Euzet; Footprints; Ichnofauna
 
  Abstract

    Is hereby described an impressive lchnoiauna belonging to the Lower to Middle Ludian of the Gard (S. France). The slab, already cleaned over a length of 18 m, is located near the top of the Potamides aporoschema lacustrine limestone (Lower Ludian, Euzet zone). It is therefore older than the Célas sandstone deposit, and still more than the Melanoides albigensis and M. acutus marly limestone corresponding to the Upper Levels of the Ludian stage. Although biostratigraphically older than the La Débruge and Montmartre zone, the biotope shows already a sampling of very tall Artiodactyles, Perissodactyles and Carnivorous. One of the most « majestic ›› Artiodactyles, Anopolotheriipus lavocati, nov., points out a huge size type. To mention also among the Ichnotypes described, 10, the big Perissodactyle Palaeotheriipus similimedius, nov., and the big Carnivorous Hyaenodontipus praedator, nov. 


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Published in Vol. 9, Ext (1980)

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Difficulties with the origin of dinosaurs: a comment on the current debate
Matthew G. Baron
Keywords: dinosaur anatomy; dinosaur evolution; Ornithoscelida; palaeobiogeography; Triassic Period

doi: 10.18563/pv.43.1.e3
 
  Abstract

    The origin and early evolutionary history of the dinosaurs is a topic that has recently gone through a period of renewed interest and academic debate. For 130 years, one way of classifying the various dinosaur subgroups persisted as the accepted model, with increasing levels of research in the past quarter-century also providing evidence for the hypothesis that dinosaur origination occurred in the Southern Hemisphere, particularly in South America. It is, after all, from within the Late Triassic strata of countries like Argentina and Brazil that we get some of the very best early dinosaur specimens; many of these specimens are the earliest known representatives of some of the major dinosaur subgroups, such as the theropods and sauropodomorphs. However, some recent analyses have brought about a shift in terms of what is currently accepted and what is now disputed regarding the origin of dinosaurs – the Southern Hemisphere origination hypothesis was questioned (although this was based upon observations and not with quantitative analysis techniques), as has the shape of the dinosaur tree. Responses to the new hypothesis were numerous; many further supported a Southern Hemisphere point of origin. Whilst the interrelationships between the major dinosaur clades remains to be resolved, the current data does seem to comprehensively answer the question of where the dinosaurs first originated. However, it is arguable whether the current data that is being used in such palaeobiogeographical analyses is sufficient to provide an answer to the question of where specifically the dinosaur clade first appeared. This short communication urges a degree of caution about the current consensus and what steps may need to be taken to ensure that more meaningful results are produced in the future. 


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Published in Vol 43-1 (2020)

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Types dentaires adaptatifs chez les sélaciens actuels et post-paléozoïques.
Henri Cappetta
Keywords: Dental types; evolution; Fossil selachians; Recent selachians; Trophic adaptations
 
  Abstract

    The dentition of selachians is characterized by an often very pronounced heterodonty involving a great morphological diversity. Despite this fact, the dentitions of selachians can be grouped in a rather reduced number of dental types corresponding to trophic adaptations: grasping, tearing, cutting, crushing, grinding and grasping-grinding type. The numerous exemples of convergence and parallelism that can be observed in fossil selachians and between Recent and fossil ones is the result of this reduced number of dental types. These dental specialisations allow to try a reconstruction of the way of life of fossil forms. 


  Article infos

Published in Vol. 16, Fasc. 2 (1986)

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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; Paleogene; 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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Physogaleus hemmooriensis (Carcharhinidae, Elasmobranchii), a new shark species from the early to middle Miocene of the north sea basin.
Thomas Reinecke and Kristiaan Hoedemakers
Keywords: Carcharhinidae; Early Miocene; Elasmobranchii; Hemmoorian; new species; North Sea Basin; Physogaleus
 
  Abstract

    A new carcharhinid shark species, Physogaleus hemmooriensis sp. nov., is described from the Lower Hemmoorian (Behrendorfian, late Burdigalian, early Miocene) of Werder, Lower Saxony, Germany. P. hemmooriensis also occurs in the Edegem and Antwerpen Sands Members of the Berchem Formation, Belgium, and in the Miste Bed, Aalten Member of the Breda Formation, The Netherlands, which have an early to middle Miocene age. In the Western Atlantic region, the taxon is present in the early Miocene Calvert Formation of Delaware, U.S.A, which is largely contemporaneous with the Hemmoorian. 


  Article infos

Published in Vol. 34, Fasc. 1-2 (2006)

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New material of “Eurysternidae” (Thalassochelydia, Pan-Cryptodira) from the Kimmeridgian of the Swiss Jura Mountains
Christian Püntener, Jérémy Anquetin and Jean-Paul Billon-Bruyat
Keywords: Eurysternidae; Late Jurassic; morphology; Switzerland; Testudines; Thalassochelydia

doi: 10.18563/pv.43.1.e2
 
  Abstract

    The region of Porrentruy (Swiss Jura Mountains) is known for its rich and diverse assemblage of Late Jurassic coastal marine turtles (Thalassochelydia). Dominated by the “Plesiochelyidae”, this assemblage also includes representatives of the two other thalassochelydian groups, the “Thalassemydidae” and “Eurysternidae.” In this study, we present new shell-based material from Porrentruy referable to eurysternids. One specimen represents a juvenile individual or a relatively small taxon, and is notably characterized by a well fenestrated plastron exhibiting a wider than long central plastral fontanelle. Two other specimens are much larger and possibly represent the largest eurysternids known to date. The fourth specimen is characterized by a unique plastral morphology otherwise only known in very small juveniles. This is the first time this unique plastral morphology is known to persist in an adult or subadult. The new material described herein represents at least three distinct taxa, all of them probably new. However, we refrain from naming new species based on this incomplete material in order to avoid adding confusion to an already complex taxonomical situation. This study provides new insights into the great diversity of eurysternids during the Late Jurassic. 


  Article infos

Published in Vol 43-1 (2020)

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