Abstract
ICHTHYOSAURS are extinct marine reptiles, probably belonging to the Diapsida1, that ranged from the Early Triassic to Late Cretaceous2,3. Post-Triassic ichthyosaurs achieved the highest level of aquatic adaptation among reptiles4, with a streamlined body, lunate tail and a dorsal fin, features exemplified today by thunniform (tuna-like) fishes. However, little is known of how such a body plan evolved from a terrestrial diapsid. Here we report the most complete specimen of the oldest known ichthyosaur, Chensaurus, representing a transition between the two body plans. The specimen, which has a partial skin impression, has a small caudal fin, a long and narrow body, and a high presacral vertebral count. These features all suggest an anguilliform swimming mode. Later ichthyosaurs retained the high vertebral count, but overcame the high swimming costs of this plesiomorphy, achieving a rigid tunniform bauplan by evolving discoidal vertebrae, and a deep fusiform body. Chensaurus therefore seems to be an evolutionary intermediate between the shorter-bodied terrestrial stock from which the group evolved, and advanced thunniform ichthyosaurs.
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References
Massare, J. A. & Callaway, J. M. Geol. Soc. Am. Bull. 102, 409–416 (1990).
Baird, D. Mosasur 2, 129–133 (1984).
Callaway, J. M. & Massare, J. A. Neues Jb. Geol. Palaont Mh. 178, 37–58 (1989).
Carroll, R. L. Spec. Pap. Palaeont. 33, 145–155 (1985).
Chen, L.-Z. Reg. Geol. China 15, 139–146 (1985).
Mazin, J.-M., Suteethom, V., Buffetaut, E., Jaeger, J.-J. & Helmcke-Ingavat, R. C. r. hebd. Séanc. Acad. Sci., Paris 313, 1207–1212 (1991).
Wang, G. X. Marine Facies of Triassic System of Anhui 1–73 (Anhui Science and Technology, Hefei, 1984).
McGowan, C. Palaeontology 35, 555–570 (1992).
Webb, P. W. & Blake, R. W. in Functional Vertebrate Morphology (eds Hildebrand, M., Bramble, D. M., Liem, K. F. & Wake, D. B.) 110–128 (Harvard Univ. Press, Cambridge, MA, 1985).
Webb, P. W. & Keyes, R. S. Fish. Bull. F.A.O. 89, 803–812 (1982).
Thomson, K. S. & Simanek, D. E. Am. Zool. 17, 343–354 (1977).
Webb, P. W. Am. Zool. 28, 709–725 (1988).
Massare, J. A. Paleobiology 14, 187–205 (1988).
Romer, A. S. The Osteology of the Reptiles 1–772 (Univ. Chicago Press, 1956).
Hoffstetter, R. & Gasc, J.-P. in Biology of the Reptilia Vol. 1 (eds Gans, C., Bellairs, A. d'A. & Parsons, T. S.) 201–310 (Academic, New York, 1969).
McGowan, C. Life Sci. Contr. R. Ont. Mus. 97, 1–37 (1974).
McGowan, C. Life Sci. Contr. R. Ont. Mus. 100, 1–30 (1974).
McGowan, C. Palaeontogr. am. A166, 93–135 (1979).
Merriam, J. C. Mem. Univ. Calif. 1, 1–196 (1908).
Kosch, B. F. J. Vertebr. Paleontol. 10, 512–514 (1990).
Riess, J. Palaeontogr. am. A192, 93–155 (1986).
Springer, V. G. & Garrick, J. A. F. Proc. U.S. natn. Mus. 116, 73–96 (1964).
Kuhn-Schnyder, E. Neujahrsblatt, Die Triasfauna der Tessiner Kalkalpen 1–119 (Natur-forschenden Gesselschaft, Zurich, 1974).
Last, P. R. & Stevens, J. D. Sharks and Rays of Australia 1–513 (CSIRO Australia, 1994).
Hauff, B. & Hauff, R. B. Das Holzmadenbuch 1–136 (Repro-Druck, Fellbach, 1981).
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Motani, R., H., Y. & McGowan, C. Eel-like swimming in the earliest ichthyosaurs. Nature 382, 347–348 (1996). https://doi.org/10.1038/382347a0
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DOI: https://doi.org/10.1038/382347a0
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