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- Sanchez, Sophie, et al.
(author)
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A new tool for determining degrees of mineralization in fossil amphibian skeletons : The example of the Late Palaeozoic branchiosaurid Apateon from the Autun Basin, France
- 2010
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In: Comptes rendus. Palevol. - : Elsevier BV. - 1631-0683 .- 1777-571X. ; 9:6-7, s. 311-317
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Journal article (peer-reviewed)abstract
- Studying ontogenetic features of fossil tetrapods is of major interest for investigating the adaptive strategies of early tetrapods to their palaeoenvironments. To determine the degree of calcification of skeletal elements, biologists have until now relied on X-ray radiographs of organisms or isolated bones, or on thin sections. An X-ray tomographic scan of Apateon, a Carboniferous - Permian branchiosaurid from the Autun Basin, France, reveals distinct density properties related to different mineralized tissues (calcified cartilage versus bone). The rendering of Apateon as a "test individual" provides a 3D map of the degrees of ossification of the axial and cranial elements. The combination of these anatomical observations with histological information from classical thin sections made in limb bones of several other specimens of the same locality allows the detailed determination of their ontogenetic stage. A comparison with the well-known specimens of the Saar-Nahe Basin, Germany, makes it possible to investigate the influence of different palaeoenvironments on ontogenetic features.
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| 4. |
- Blieck, Alain, et al.
(author)
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The biostratigraphic and Palaeogeographic framework of the earliest diversification of tetrapods (Late Devonian) - a critical review
- 2007
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In: Terrestrialization influenses on the Palaeozoic geosphere-biospere (Workshop ECLIPSE II, Paris, 8-9 october).
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Conference paper (pop. science, debate, etc.)abstract
- Ichthyostega was the first Devonian tetrapod to be subject to a whole-body reconstruction and remains, together with Acanthostega one of only two Devonian tetrapods for which near-complete postcranial material is available. It is thus crucially important for our understanding of the earliest stages of tetrapod evolution and terrestrialization. Based on extensive re-examination of original material, augmented by recently collected specimens, we present a new reconstruction of Ichthyostega that differs substantially from those previously published and reveals hitherto unrecognised regionalization in the vertebral column. Ichthyostega is the earliest vertebrate to show obvious adaptations for non-swimming locomotion. Uniquely among early tetrapods, the presacral vertebral column shows pronounced regionalization of neural arch morphology, suggesting that it was adapted for dorsoventral rather than lateral flexion.
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| 6. |
- Clément, Gaël, et al.
(author)
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A new tristichopterid (Sarcopterygii, Tetrapodomorpha) from the Upper Famennian Evieux Formation (Upper Devonian) of Belgium
- 2009
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In: Palaeontology. - : Wiley. - 0031-0239 .- 1475-4983. ; 52, s. 823-836
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Journal article (peer-reviewed)abstract
- Additional material of a large specimen of tristichopterid fish from the Upper Famennian Evieux Formation of Belgium is described. This large fish was previously assigned to Tristichopteridae gen. et sp. indet. due to the lack of diagnostic anatomical data. New available material consists of the internal surface of the parietal shield, vomers and anterior part of the parasphenoid, subopercular and submandibulo-branchiostegal bones, and an internal view of the anterior part of the mandible. A possible autapomorphy of the new form from Belgium, Langlieria socqueti gen. nov. et sp. nov., is the absence of marginal teeth on the vomer except on its most lateral part. Apart from these features, it only differs from the genus Mandageria from Australia in the absence of marginal teeth between the dentary fang and the mandibular symphysis, in the presence of a raised marginal crest lateral to the anterior coronoid fang, and in the presence of numerous small marginal teeth on the premaxilla. It differs from the cosmopolitan genus Eusthenodon in a number of respects: the supratemporal, tabular, and postparietal bones are superficially fused, as are the intertemporal and parietal bones, the dermal ornament is proportionally very fine, and the denticulated field of the parasphenoid stands proud rather than being recessed into the body of the bone.
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