Thecodontosaurus

Thecodontosaurus ("socket-tooth lizard") is a genus of herbivorous basal sauropodomorph dinosaur that lived during the late Triassic period (Carnian age). Its remains are known mostly from Triassic "fissure fillings" in southern England. Thecodontosaurus was a small bipedal animal, about long. It is one of the first dinosaurs to be discovered and is one of the oldest that ever existed. Many species have been named within the genus, but only the type species Thecodontosaurus antiquus is seen as valid today.

==Discovery and naming== ===Thecodontosaurus antiquus=== thumb|left|Size comparison In the autumn of 1834, surgeon Henry Riley (1797–1848) and the curator of the Bristol Institution, Samuel Stutchbury, began to excavate "saurian remains" at the quarry of Durdham Down, at Clifton, presently a part of Bristol, which is part of the Magnesian Conglomerate. In 1834 and 1835, they briefly reported on the finds. They provided their initial description in 1836, naming a new genus: Thecodontosaurus. The name is derived from Greek θήκή, ', "socket", and οδους, ', "tooth", a reference to the fact that the roots of the teeth were not fused with the jaw bone, as in present lizards, but positioned in separate tooth sockets. Thecodontosaurus was the fifth dinosaur named, after Megalosaurus, Iguanodon, Streptospondylus and Hylaeosaurus, though Riley and Stutchbury were not aware of this, the very concept of Dinosauria only being created in 1842. In 1843, in his catalogue of British fossils, John Morris provided a complete species name: Thecodontosaurus antiquus. The specific epithet, "antiquus", means "ancient" in Latin.