Topic
Claudiosaurus
About: Claudiosaurus is a research topic. Over the lifetime, 3 publications have been published within this topic receiving 143 citations.
Papers
TL;DR: The nature of the Upper Permian sediments in Madagascar and the tectonic environment of their deposition indicate accumulation in deep rift valleys, some parts of which were open to the sea, and the presence of oolites replaced with collophane suggests a rich phosphate source such as deep marine upwellings.
Abstract: Numerus well preserved fossils from the Upper Permian of Madagascar are structurally intermediate between primitive diapsid reptiles and nothosaurs and plesiosaurs. Claudiosaurus germaini (gen.nov., sp.nov.) is similar in its basic anatomy to eosuchian reptiles such as Thadeosaurus colcanapi (gen.nov., sp.nov.), but the absence of a lower temporal bar and the closure of the palate are characteristics of sauropterygian reptiles. Claudiosaurus shows the initiation of aquatic adaptations in the proportions and reduced ossification of the carpus and manus. A third pair of sacral ribs is partially incorporated. The small size of the skull, the nature of the palate and marginal dentition and the long neck are suggestive of aquatic feeding habits. Claudiosaurus does not, however, show the specific adaptations for aquatic locomotion seen in either nothosaurs or plesiosaurs. Even the most primitive known species of nothosaurs and plesiosaurs are too specialized in the postcranial skeleton for direct comparison with Claudiosaurs , although the similarities to the skull roof of primitive nothosaurs are very close. The configuration of the cheek in nothosaurs almost certainly resulted from the loss of the lower temporal bar from a pattern like that of Youngina , rather than from the ventral emargination of the cheek. The nature of the Upper Permian sediments in Madagascar and the tectonic environment of their deposition indicate accumulation in deep rift valleys, some parts of which were open to the sea. The presence of oolites replaced with collophane suggests a rich phosphate source such as deep marine upwellings. Similar upwellings of phosphate have also been associated with the evolution of the marine iguanas on the Pacific coast of South America. The concept of the derivation of nothosaurs from protorosaurs or araeosceloids may be traced to misunderstandings of the nature of the cheek in both Nothosaurus and Protorosaurus . Araeoscelis , despite the possession of a solid cheek, is closely related to Petrolacosaurus , an ancestral diapsid.
110 citations
TL;DR: Histological study of the skeleton of Claudiosaurus germaini reveals extensive pachyostosis, which suggests that Claudiosaur was an aquatic reptile that probably had a distinct physiological significance.
Abstract: Histological study of the skeleton of Claudiosaurus germaini reveals extensive pachyostosis. This feature results from the filling of intra‐osseous cavities by centripetal, endosteal deposits and occurs in conjunction with an intense remodelling of the bones by resorption and re‐deposition. Epiphyseal calcified cartilages are rapidly and entirely resorbed. Extensive pachyostosis suggests that Claudiosaurus was an aquatic reptile. However, the pachyostotic condition in this genus appears histogenetically quite different from the common type of pachyostosis observed in other aquatic tetrapods. Hence, it probably had a distinct physiological significance.
50 citations
5 Aug 2019
TL;DR: Claudiosaurus skeletal anatomy provides evidence for swim propulsion by both hind limbs and by undulation of a dorsal-ventrally flattened tail, whereas other Permian aquatic reptile genera used snake-like side-to-side tail undulation, whereas Claudiosaurus used cetacean-like up-down Tail undulation in the vertical plane.
Abstract: Eight amniote genera (representing four clades) became aquatic during the Permian. The four clades were mesosaurids, tangasaurids, the neodiapsid Claudiosaurus, and the procolophonid Barasaurus. Two of eight genera survived the end-Permian mass extinction, but did not last long into the Mesozoic. A previously undescribed specimen of Claudiosaurus germaini, preserved in a lacustrine concretion from the Sakamena Formation, Madagascar, bears seventeen vertebrae that has been split along an approximate horizontal plane to reveal sections of neural canal casted in white calcite. Enlargement of the neural canal in the sacral region of this specimen of Claudiosaurus (vertebral segments 22-26) is more similar to that of Tupinambis (segments 24-28) than it is to Testudo (segments 16-23). Claudiosaurus skeletal anatomy provides evidence for swim propulsion by both hind limbs and by undulation of a dorsal-ventrally flattened tail. Evidence for the latter includes elongate transverse processes on distal tail vertebrae. Other Permian aquatic reptile genera (Mesosaurus, Hovasaurus, Barasaurus) used snake-like side-to-side tail undulation, whereas Claudiosaurus used cetacean-like up-down tail undulation in the vertical plane. It seems unlikely that any of these animals were particularly fast swimmers.
2 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2019 | 1 |
| 1989 | 1 |
| 1981 | 1 |