A new specimen of Teleidosaurus calvadosii (Eudes-Deslongchamps, 1866) (Crocodylia, Thalattosuchia) from the Middle Jurassic of France

Abstract

Our understanding of early metriorhynchid evolution, the highly specialised pelagic clade of Mesozoic crocodylomorphs, is hampered by the paucity of basal metriorhynchoids and how poorly preserved most of these fossils are. This means the transition from a ‘gharial-like’ body-plan to a ‘pseudo-dolphin-like’ one, which characterises metriorhynchoid evolution, is still poorly understood. Herein the Middle Jurassic taxon Teleidosaurus calvadosii (J.A. Eudes-Deslongchamps, 1866) is re-evaluated. The holotype of T. calvadosii was destroyed during World War Two, as were all referred specimens. All that survived are plaster casts of the holotype. However, a recently discovered specimen from the middle Bathonian of Ecouché, Normandy, France is herein referred to T. calvadosii. This specimen preserves the antorbital region, an incomplete mandible and one cervical vertebra. This specimen is designated as neotype of T. calvadosii. The new specimen allows to re-evaluate the anatomy of T. calvadosii, in particular the antorbital fenestra, which has been misunderstood. Moreover, a comparison is made between the French Middle Jurassic metriorhynchoids Teleidosaurus and Eoneustes. Both genera appear as valid and E. bathonicus is considered to be a nomen dubium.