A juvenile plesiosaur from the Pliensbachian (Lower Jurassic) of Asturias, Spain

Abstract

Mesozoic marine reptiles are poorly known in Spain (see Quesada et al., 1998 for a bibliography). Up to now, the plesiosaur record of Spain consisted only of fragmentary remains coming from the Jurassic of Asturias (Schulz, 1858; Ruiz-Omeñaca et al., 2006) and the Cretaceous of the Basque Country and Castellón (Bardet et al., 1999a; Yagüe et al., 2003). The Asturias record includes (1) an historical nineteenth century specimen (now lost)—one of the oldest fossil reptiles from Spain—briefly mentioned as “part of a skeleton and paddles of a plesiosaur, which largest vertebrae reach a diameter of 6 cm, found in Lower Jurassic rocks (most probably Rodiles Formation, Pliensbachian, J. C. G.-R. pers. obs.), between the localities of El Puntal and Tazones in Villaviciosa” (Schulz, 1858:108). Unfortunately, no figure was provided and we have no definitive certitude about the plesiosaurian affinities of this specimen. (2) isolated remains from the Lower Jurassic (HettangianSinemurian; Gijón Formation) and Upper Jurassic (Kimmeridgian; Tereñes Formation) of the same area (Ruiz-Omeñaca et al., 2006). Here we report on the discovery of an immature plesiosaur from the Pliensbachian of Asturias. It is the most complete plesiosaur specimen found in Spain, one of the very few juvenile plesiosaurs known worldwide, and an additional specimen from the very poor Pliensbachian fossil record.