Thecodontosaurus

Thecodontosaurus ("socket-tooth lizard") is a genus of herbivorous basal sauropodomorph dinosaur that lived during the late Triassic period (Rhaetian age).Its remains are known mostly from Triassic "fissure fillings" in South England. *Thecodontosaurus* was a small bipedal animal, about 2 m (6.5 ft) long. It is one of the first dinosaurs to be discovered and is one of the oldest that existed. Many species have been named in the genus, but only the type species *Thecodontosaurus antiquus* is seen as valid today.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, '**thēkē'**, "socket", and οδους, '**odous'**, "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.The original type specimen or holotype of *Thecodontosaurus*, BCM 1, a lower jaw, fell victim to heavy World War II bombings. Many remains of this dinosaur and other material related to it were destroyed in November 1940 during the Bristol Blitz. However, most bones were salvaged: today 184 fossil bones are part of the collection of the Bristol City Museum and Art Gallery. Later, more remains were found near Bristol at Tytherington. Currently about 245 fragmentary specimens are known, representing numerous individuals. In 1985, Peter Galton designated another lower jaw, a right dentary, as the neotype, BCM 2. The remains had been found in chalkstone infillings, breccia deposited in fissures in older rocks. The age of these deposits was once estimated as old as the late Carnian, but recent studies indicate that they date from the Rhaetian.Apart from the original type species, *Thecodontosaurus antiquus*, Riley and Stutchbury also found some teeth of carnivorous phytosaurians that they named *Palaeosaurus cylindrodon* and *P. platyodon*. In the late nineteenth century, the theory became popular that such remains belonged to carnivorous prosauropods: animals with the body of *Thecodontosaurus*, but with slicing teeth. In 1890, Arthur Smith Woodward accordingly named a *Thecodontosaurus platyodon,* and in 1908 Friedrich von Huene named a *Thecodontosaurus cylindrodon*. Though still defended by Michael Cooper in 1981, the hypothesis that such creatures existed has now been totally discredited.Apart from the original type species, *Thecodontosaurus antiquus*, Riley and Stutchbury also found some teeth of carnivorous phytosaurians that they named *Palaeosaurus cylindrodon* and *P. platyodon*. In the late nineteenth century, the theory became popular that such remains belonged to carnivorous prosauropods: animals with the body of *Thecodontosaurus*, but with slicing teeth. In 1890, Arthur Smith Woodward accordingly named a *Thecodontosaurus platyodon,* and in 1908 Friedrich von Huene named a *Thecodontosaurus cylindrodon*. Though still defended by Michael Cooper in 1981, the hypothesis that such creatures existed has now been totally discredited.Apart from the original type species, *Thecodontosaurus antiquus*, Riley and Stutchbury also found some teeth of carnivorous phytosaurians that they named *Palaeosaurus cylindrodon* and *P. platyodon*. In the late nineteenth century, the theory became popular that such remains belonged to carnivorous prosauropods: animals with the body of *Thecodontosaurus*, but with slicing teeth. In 1890, Arthur Smith Woodward accordingly named a *Thecodontosaurus platyodon,* and in 1908 Friedrich von Huene named a *Thecodontosaurus cylindrodon*. Though still defended by Michael Cooper in 1981, the hypothesis that such creatures existed has now been totally discredited.