Abstract

Post-Triassic ichthyosaurus are characterized by a tailbend, a downward flexure of the vertebral column that forms the internal skeleton of the lower lobe of the caudal fin. The tailbend arises because several of the vertebrae at the apex of the bend have wedge-shaped centra. There has recently been some question whether the swordfish-like ichfhyosaur Eurhinosaurus, from the upper Liassic (Toarcian), had a tailbend. However, computed tomography of the tail region of an unprepared specimen from the Holzmaden area of Germany confirms a tailbend. This is angled at about 40° to the horizontal, which is less steeply downturned than early restorations depicted, but fairly steep compared with other upper Liassic species. Five markedly wedge-shaped centra, contribute to the tailbend, with lesser degrees of wedging in two others.

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