Oryctos
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Accès privé :
| volume 5, 2004 |
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Julien Claude & Haiyan Tong, Early Eocene testudinoid turtles from Saint Papoul, France, with comments on the early evolution of Testudinoidea. Oryctos 5, 3-45
The description of three Early Eocene fossil turtle species from southern France illustrates the early Eocene radiation of Testudinoidea, the largest group of recent turtles. Two species of Geoemydid Palaeoemys Schleich,1994, P. testudiniformis (Owen, 1842) and P. hessiaca Schleich, 1994, are described on the basis of new shell material from the Ypresian (Early Eocene) locality of Saint Papoul (Aude, France). A new species belonging to the family Testudinidae, Achilemys cassouleti, is interpreted as the most primitive taxon of this family. In order to assess their phylogenetic relationships, an evolutionary scenario is proposed mainly on the basis of newly published studies in molecular phylogeny, followed by paleobiogeographical considerations, and by reappraisal of morphological character evolution. Keywords: Early Eocene, Southern France, Testudines, Cryptodira, Testudinoidea, Palaeoemys, Achilemys, Phylogeny
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Marie-Céline Buchy , Philippe Taugourdeau & Philippe Janvier. Stomach contents of a Lower Triassic ichthyosaur from Spitzbergen. Oryctos 5, 47-55.
The stomach contents of a Lower Triassic ichthyosaur from Spitzbergen are here described for the first time. The stomach contents are now lost, and the description relies on unpublished photographs and a description made in the 70’s. The specimen is a juvenile that has been previously identified as Grippia longirostris, but the re-examination of the specimen and original literature contradicts this attribution. It is here provisionally assigned to cf. Merriamosaurus hulkei. Its stomach contents consist of black hooks identified as remnants of belemnoid cephalopods and annelids, which have never before been described in this context. The hypothesis that these annelid remains represent the gastric contents of the preyed cephalopods is discussed. The specimen would then represent one of the rare examples of a preserved partially preserved Mesozoic marine trophic web.
Keywords: Ichthyosauria, Lower Triassic, diet, cephalopod hooks, annelids, stomach contents
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Stéphane Hua, Crocodilians from the Sparnacian (Lower Eocene) of Le Quesnoy (Oise, France). Oryctos 5, 57-62.
A complete description of the crocodilian fauna from the Sparnacian (Early Eocene, MP7) of “le Quesnoy” (Oise, northern France) is provided. The much debated systematic position and affinities of the genus Diplocynodon, which is found at Le Quesnoy, are discussed, and the genus is placed in the family Diplocynodontidae. There are two additional genera at this locality: the alligatorid Allognathosuchus and the crocodylid Asiatosuchus.
Keywords: Asiatosuchus, Allognathosuchus, Diplocynodon, Oise, Lower Eocene
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Eric Buffetaut, An Iguanodon jaw (Dinosauria, Ornithopoda) from the Lower Cretaceous of Aube (eastern Paris Basin, France). Oryctos 5, 63-68
A dentary fragment in the collections of the Troyes Natural History Museum is described and identified as Iguanodon sp. The specimen was found sometime during the nineteenth century at Bernon, a village in the “Champagne humide” about 36 km south of Troyes. The matrix shows that this jaw fragment comes from the Hauterivian Calcaire à Spatangues, a shallow marine limestone which has yielded Iguanodon remains at other places in the eastern Paris Basin. The specimen is interpreted as an element of a floating carcass originating from a nearby land mass.
Keywords: Dinosauria, Iguanodon, Dentary, Cretaceous, Hauterivian, Paris Basin
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Gilles Cuny, A Late Triassic Cynodont from Holwell Quarries (Somerset, England). Oryctos 5, 69-73.
The presence of the dromatheriid cynodont Pseudotriconodon wildi is reported from the Rhaetian of Great Britain in the fissure deposits at Holwell Quarries. The British Rhaetic cynodont fauna, although consisting only of a dromatheriid tooth, one tooth of Tricupes, and one tritylodontid fragmentary jaw, is similar to that found in the Germanic Realm. It appears to be the remnant of a fauna that covered all of Western Europe before the fragmentation of its habitat due to the Rhaetian transgression.
Keywords: Cynodontia, Triassic, Rhaetian, Great Britain, Europe
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Richard Smith & Thierry Smith, Are the mammals from the middle Ypresian of the Paris Basin (reference-level MP8-9) already present from the Paleocene/Eocene boundary at Dormaal (reference-level MP7, Belgium)? Oryctos 5, 75-82.
Multituberculate mammals are not present in the Dormaal site (MP7, Paleocene-Eocene transition in Belgium) contrary to what Delsate (2000) put forward. The presence of two multituberculate teeth described by this author as well as 4 other teeth of placental mammals and numerous teeth of characiform fishes from the Delsate collection seem to be due to contamination, resulting from the screen washing of sediments collected at a Middle Ypresian site of the Paris Basin (MP8-9). The contaminated material consists of 5 mammal species and 1 characiform species, which are absent in all the other collections from Dormaal (comparisons were made on the basis of 14000 mammal specimens pertaining to 50 taxa). On the other hand, these 6 taxa are typical for the MP8-9 faunas of the Reims area in the Paris Basin. This study also shows that the perissodactyl Hallensia louisi Hooker, 1994 is not present in reference-level MP7 of Dormaal.
Keywords : Dormaal, Delsate collection, contamination
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Aurora Grandal-d'Anglade & Fernando Lopez-Gonzalez, A study of the evolution of the Pleistocene cave bear by a morphometric analysis of the lower carnassial. Oryctos 5, 83-94.
In this contribution a morphometric study of the lower carnassial of the Cave Bear (Ursus deningeri and Ursus spelaeus) from several populations of diverse European localities and also different ages is carried out. This study includes a morphological analysis of the deployment of dental cusps and metric comparisons focused on general size and convergence of the cusps. The morphologic study (by cluster analysis) presents a grouping trend of the populations according to their geographic position first, then to the chronology. This indicates that the expansion of the cave bear happened at a very early time, and that later did not exist great migratory movements that returned to put in contact remote populations. As for the metric analysis, differences in the degree of convergence of the cusps in the talonid and trigonid are only observed between the oldest sites (more convergent, smaller occlusal surface) and the modern ones (less convergent, larger occlusal surface) independently of the geographic location.
Keywords : cave bear, lower carnassial, morphometry, evolution, Pleistocene, Europe
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