Diet: Thecodontosaurus was an herbivore (a plant eater or a primary consumer). It probably ate cycads, palms, and other low-lying plants. It had blunt teeth with serrated edges; they resembled the teeth of a monitor lizard, but were embedded in distinct sockets in the opposing jaw (Thecodontosaurus was named for its unusual teeth).

Anatomy: Thecodontosaurus was about 7 feet (2.1 m) long. It had a small head, large thumb claws, long legs, a relatively short neck, shorter arms than legs, and a long tail. It could probably walk on two or four legs, perhaps grazing and walking on all fours, but running on two legs. Thecodontosaurus had four toes on each foot and five fingers on each hand (including a thumb with a large, curved claw).

Fossils and Name: Fossils of Thecodontosaurus have been found in England (near Bristol) and Wales, which were probably dry and desert-like when Thecodontosaurus lived. Thecodontosaurus (meaning "socket-toothed lizard") was named by Morris in 1843, but was first described by H. Riley and S. Stutchbury in 1836. The type species is T. antiquus (Morris, 1843).