El fósil de plesiosaurio (Sauropterygia) más antiguo de la Península Ibérica: una vértebra procedente del Hettangiense-Sinemuriense de Asturias

Abstract

In this paper, a pectoral vertebra of a plesiosaur is described. It comes from an exposure of the upper member of the Gijón Formation (lower Hettangian - basal Upper Sinemurian) in the coastal cliffs of the Villar hamlet in the Villaviciosa municipality (Asturias, Northern Spain). The specimen is not diagnostic further away from the superfamily level, and is assigned to a Plesiosauroidea indet. The Villar vertebra is the first vertebrate remain from the Gijón Formation and the oldest Mesozoic vertebrate fossil found in Asturias. Moreover, it represents currently the oldest record of plesiosaurs from the Iberian Peninsula, predating another indeterminate plesiosauroid specimen from the basalmost Pliensbachian of Villaviciosa (Asturias). It also represents the westernmost occurrence of Early Liassic plesiosaurs in the Tethys Ocean