Abstract
ABSTRACT Thecodontosaurus antiquus is 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 with T. antiquus and other Late Triassic sauropodomorphs from Britain. We find that this material can be assigned to T. antiquus based 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 contemporary Pantydraco caducus from T. antiquus, such that the former might represent a juvenile of the latter. We also discuss the questionable validity of Asylosaurus yalensis. Thecodontosaurus antiquus is 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.
Highlights
Dinosaurs are a clade of avemetatarsalian archosaurs that originated in Gondwana in the Middle–Late Triassic (Marsola et al, 2019), splitting early in their history into three main lineages (Baron et al, 2017; Langer et al, 2017) and rising to ecological dominance by the EarlyJurassic (Brusatte et al, 2008a; 2008b)
One of these Late Triassic sauropodomorphs was Thecodontosaurus antiquus, which lived in the region that today forms the British Isles (Benton et al, 2000) and occupies a basal phylogenetic position as a nonplateosaurian sauropodomorph (Benton et al, 2000; Otero and Pol, 2013; Langer et al, 2019)
Thecodontosaurus was named and described by Riley and Stutchbury (1836; 1840) from dinosaurian material found in the fissure fill deposit of Durdham Down in Bristol, U.K
Summary
This is the author accepted manuscript (AAM). We describe the osteology of the Tytherington specimens, comparing them to T. antiquus and other Late Triassic sauropodomorphs from Britain. We find that this material can be assigned to T. antiquus based on multiple shared morphological traits, and we provide a revised diagnosis of this taxon. Thecodontosaurus is one of the most basal sauropodomorphs that shows 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
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