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Peculiarities of the Structure and Locomotor Function of the Tail in Sauropterygia


Among ancient and modern marine reptiles, several structural types of the locomotor apparatus were or are present, supporting different styles of swimming. Ichthyosaurs, mosasaurs, saltwater crocodiles, and representatives of many other groups swam or swim with horizontal undulations of the body primarily using the tail with a vertical caudal fin. Sea turtles with a reduced tail and their body completely immobilized by the shell use only limbs transformed into flippers for swimming. Sauropterygians had a substantially immobilized trunk and a horizontal caudal fin. They used a unique type of subaquatic locomotion with the leading role of two pairs of powerful flippers and vertical undulations of the tail, partial analogs of which are found in sea turtles, sirens, cetaceans, and some semi-aquatic mammals.

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This work was supported by state subsidies to Kazan Federal University towards the increase of its competitiveness among the world’s leading scientific and educational centers, as well as by the Russian Foundation for Basic Research (project nos. 17-04-00410, 16-05-00711, and 17-54-10013).

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Sennikov, A.G. Peculiarities of the Structure and Locomotor Function of the Tail in Sauropterygia. Biol Bull Russ Acad Sci 46, 751–762 (2019).

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  • marine reptiles
  • Sauropterygia
  • Mesozoic
  • subaquatic locomotion
  • tail morphology
  • fins