shorter than the legs, and its tail was much longer than the head, neck and body put together. On average, it was long, or 1 ft. tall, and weighed . The largest individuals had an estimated length of . In 2000, Michael Benton noted the existence of a robust morph in the population, seen by him as a possible second species or, more likely, an instance of sexual dimorphism. Benton also indicated some unique derived traits, or autapomorphies, for the species: a long basipterygoid process on the braincase; a dentary that is short in relation to the total length of the lower jaw; an ilium that has a back end that is subquadrate instead of rounded. The small size has been explained as an instance of insular dwarfism. Classification Riley and Stutchbury originally saw Thecodontosaurus as a member of the Squamata, the group containing lizards and snakes. This did not change when Richard Owen coined the term Dinosauria in 1842, because Owen did not recognise Thecodontosaurus as a dinosaur; in 1865, he assigned it to the Thecodontia. It was not until 1870 that Thomas Huxley became the first person to understand that it was a dinosaur, though referring it incorrectly to the Scelidosauridae. Later, it was placed in either the Anchisauridae or its own Thecodontosauridae alongside Agrosaurus. Modern exact cladistic analyses have not been conclusive. Although not actually the earliest member of the group, Thecodontosaurus is sometimes placed in a very basal position among the sauropodomorph dinosaurs. It was earlier included under the Prosauropoda, but more recently it has been suggested that Thecodontosaurus and its relatives preceded the prosauropod-sauropod split. Paleobiology Examination of Thecodontosaurus revealed it was exclusively bipedal. Studies of the muscle attachments in its fore and hindlimbs suggest that it was an extremely fast bipedal runner that relied on its weaker front limbs for grasping vegetation, cutting it up and feeding it into its mouth. Its advanced running capabilities suggest it was well adapted for high-speed sprinting, probably as a means of escaping predators. References Further reading Moody, Richard. Dinofile. Pg. 23. Octopus Publishing Group Ltd., 2006 Sauropodomorphs Rhaetian life Late Triassic dinosaurs of Europe Triassic England Fossils of England Fossils of Serbia Fossil taxa described in 1836 Taxa named by Samuel Stutchbury