Claudiosaurus
Temporal range: Lopingian
~
Specimen of Claudiosaurus germaini, on display at the Redpath Museum, Montreal
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Neodiapsida
Family: †Claudiosauridae
Carroll 1981
Genus: †Claudiosaurus
Carroll 1981
Type species
†Claudiosaurus germaini

Claudiosaurus (claudus is Latin for 'lameness' and saurus means 'lizard') is an extinct genus of diapsid reptiles from the Late Permian Sakamena Formation of the Morondava Basin, Madagascar. It has been suggested to be semi-aquatic.

History and discovery

Claudiosaurus is known from the Sakamena Formation of Madagascar. Claudiosaurus is found from the Late Permian. Although a paper mentions that they have been also found in Early Triassic deposits of Madagascar,[1] citation does not mention that Claudiosaurus is from Triassic.[2]

Description

Size compared to human hand

Individuals of Claudiosaurus reached a body length of approximately 60 centimetres (2.0 ft).[3] The body form of Claudiosaurus is generally similar to those of other basal diapsids, although the neck of Claudiosaurus is somewhat elongated, with 8 cervical vertebrae, and had a proportionally small head. The body has 16 trunk vertebrae with gastralia present on the underside, and the tail has at least 45 caudal vertebrae. The jaws had numerous small teeth, with the roof of the mouth (palate) being covered in numerous denticles.[4] The sternum is unossified.[5] The pectoral girdle is similar to those of other primitive diapsids.[6] The phalanges of the hands show a reduction of length away from the base, with the exception of the distalmost phalange of the third digit, which is longer than the preceding phalange. The terminal phalanges are flattened.[4] The bones of Claudiosaurus show pachyostosis, suggested to possibly be an adaptation for aquatic life.[7]

Ecology

Life restoration of Claudiosaurus germaini

Claudiosaurus is generally assumed to have been an amphibious animal, using its limbs for propulsion, though it was still likely capable of walking on land, and the skeleton shows only limited adaptations to aquatic life. It has been suggested to have fed on small invertebrates, such as crustaceans.[4]

Classification

Upon its original description, Robert L. Carroll suggested that Claudiosaurus belonged to Sauropterygia (which includes plesiosaurs).[4] Other later studies have generally recovered it as a basal neodiapsid, sometimes as a member of the Younginiformes.[8][9] Claudiosaurus was recovered as a relative of turtles by Li et al. (2018), forming a clade with the basal neodiapsid Acerosodontosaurus.[10] Although another study in 2020 specifically disputed these conclusions.[11]

Paleoenvironment

The Lower Sakamena Formation was deposited in a wetland environment situated within a North-South orientated rift valley, perhaps similar to Lake Tanganyika. The climate at the time of deposition was temperate, warm, and humid, with seasonal rainfall and possible monsoons.[12] Flora from the formation includes the equisetalean Schizoneura, the glossopterid gymnosperm Glossopteris, and seed fern Lepidopteris. Other vertebrates known from the Lower Sakamena Formation include the palaeoniscoid fish Atherstonia, the procolophonid parareptile Barasaurus, the gliding weigeltisaurid reptile Coelurosauravus, the neodiapsids Hovasaurus, Thadeosaurus, and Acerosodontosaurus, fragments of rhinesuchid temnospondyls, an indeterminate theriodont therapsid and the dicynodont Oudenodon.[13]

References

  1. ↑ Nuñez Demarco, Pablo; Meneghel, Melitta; Laurin, Michel; Piñeiro, Graciela (27 July 2018). "Was Mesosaurus a Fully Aquatic Reptile?". Frontiers in Ecology and Evolution. 6: 109. doi:10.3389/fevo.2018.00109. hdl:20.500.12008/30631.
  2. ↑ Ketchum, Hilary F.; Barrett, Paul M. (2011-02-09). "New reptile material from the Lower Triassic of Madagascar: implications for the Permian-Triassic extinction event". Canadian Journal of Earth Sciences. 41 (1): 1–8. doi:10.1139/e03-084.
  3. ↑ "Amphibious and Early Marine Mesozoic Reptiles", Ecology and Behaviour of Mesozoic Reptiles, Berlin/Heidelberg: Springer-Verlag, pp. 23–43, 2005, doi:10.1007/3-540-26571-6_4, ISBN 978-3-540-22421-1, retrieved 2023-10-20
  4. 1 2 3 4 "Plesiosaur ancestors from the upper permian of Madagascar". Philosophical Transactions of the Royal Society of London. B, Biological Sciences. 293 (1066): 315–383. 1981-07-16. doi:10.1098/rstb.1981.0079. ISSN 0080-4622.
  5. ↑ Canoville, Aurore; Laurin, Michel (2010-05-19). "Evolution of humeral microanatomy and lifestyle in amniotes, and some comments on palaeobiological inferences: AMNIOTE MICROANATOMY AND PALAEOBIOLOGICAL INFERENCE". Biological Journal of the Linnean Society. 100 (2): 384–406. doi:10.1111/j.1095-8312.2010.01431.x.
  6. ↑ Araújo, Ricardo; Correia, Fernando (2015-03-16). "Plesiosaur pectoral myology: Soft-tissue anatomy of the Plesiosaur pectoral girdle inferred from basal Eosauropterygia taxa and the extant phylogenetic bracket". Palaeontologia Electronica. 18 (1): 1–32. doi:10.26879/446. ISSN 1094-8074.
  7. ↑ De Buffrénil, Vivian; Mazin, Jean‐Michel (September 1989). "Bone histology of claudiosaurus germaini (reptilia, claudiosauridae) and the problem of pachyostosis in aquatic tetrapods". Historical Biology. 2 (4): 311–322. doi:10.1080/08912968909386509. ISSN 0891-2963.
  8. ↑ Simões, Tiago R.; Kammerer, Christian F.; Caldwell, Michael W.; Pierce, Stephanie E. (2022-08-19). "Successive climate crises in the deep past drove the early evolution and radiation of reptiles". Science Advances. 8 (33): eabq1898. doi:10.1126/sciadv.abq1898. ISSN 2375-2548. PMC 9390993. PMID 35984885.
  9. ↑ Pritchard, Adam C.; Sues, Hans-Dieter; Scott, Diane; Reisz, Robert R. (2021-05-20). "Osteology, relationships and functional morphology of Weigeltisaurus jaekeli (Diapsida, Weigeltisauridae) based on a complete skeleton from the Upper Permian Kupferschiefer of Germany". PeerJ. 9: e11413. doi:10.7717/peerj.11413. ISSN 2167-8359. PMC 8141288. PMID 34055483.
  10. ↑ Li, Chun; Fraser, Nicholas C.; Rieppel, Olivier; Wu, Xiao-Chun (August 2018). "A Triassic stem turtle with an edentulous beak". Nature. 560 (7719): 476–479. Bibcode:2018Natur.560..476L. doi:10.1038/s41586-018-0419-1. PMID 30135526. S2CID 52067286.
  11. ↑ Gardner, Nicholas M.; Van Vranken, Nathan E. (2020). "The Permian diapsid reptiles Acerosodontosaurus and Claudiosaurus are not stem-turtles: Morphological and fossil phylogenetic analyses must take a cautious, holistic approach toward turtle origins". Proceedings of the West Virginia Academy of Science. Nicholas M. Gardner and Nathan E. Van Vranken. 92. doi:10.55632/pwvas.v92i1.626. S2CID 248952833. Retrieved April 29, 2020.
  12. ↑ Buffa, Valentin; Frey, Eberhard; Steyer, J.-Sébastien; Laurin, Michel (4 March 2021). "A new cranial reconstruction of Coelurosauravus elivensis Piveteau, 1926 (Diapsida, Weigeltisauridae) and its implications on the paleoecology of the first gliding vertebrates" (PDF). Journal of Vertebrate Paleontology. 41 (2): e1930020. Bibcode:2021JVPal..41E0020B. doi:10.1080/02724634.2021.1930020. S2CID 237517962.
  13. ↑ Smith, Roger M. H. (2000). "Sedimentology and taphonomy of Late Permian vertebrate fossil localities in southwestern Madagascar". hdl:10539/16377. {{cite journal}}: Cite journal requires |journal= (help)

Further reading

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