Osteological redescription of the Late Triassic sauropodomorph dinosaurThecodontosaurus antiquusbased on new material from Tytherington, southwestern England

Thecodontosaurus antiquusis a basal sauropodomorph from the Rhaetian locality of Durdham Down in Bristol, U.K. Sauropodomorph material putatively assigned to this species was found at the nearby site of Tytherington. Here, we describe the Tytherington specimens and compare them withT. antiquusand other Late Triassic sauropodomorphs from Britain. We find that this material can be assigned toT. antiquusbased on multiple shared morphological traits, and we provide a revised diagnosis of this taxon. The new anatomical information from the Tytherington specimens enriches the osteology of the species, particularly of previously unknown parts of the skeleton such as the skull. We find poor anatomical support to distinguish the contemporaryPantydraco caducusfromT. antiquus, such that the former might represent a juvenile of the latter. We also discuss the questionable validity ofAsylosaurus yalensis.Thecodontosaurus antiquusis one of the most basal sauropodomorphs that show craniodental traits related to herbivory, while retaining a plesiomorphic limb morphology and posture. This taxon was an important component of Rhaetian insular ecosystems of southwestern Britain.