AbstraetThe Triassic is the period of the main radiation of the reptiles. Numerous new orders are developing such as the thecodonts, saurisehians and ornithisehians [dinosaurs], the erocodilians, pterosaurs, sauropterygians, lizards, the sphenodonts and rhynehosaurs, generally classified as rhynchocephalians, the ehelonians, iehthyosaurs, placodonts and therapsids. Their phylogenetic relations are still partly unknown. The step towards conquering new habitats on land, in the sea and in the air, the trend towards gigantic size, the development of armour, the improvement of gait and the aehievment of endothenny enabled the reptiles to dominate the earth absolutely during the Mesozoic. Moreover the obviously explosive evolution of the reptiles in the Triassie led to the development of two new classes of vertebrates, the birds and the mammals. Some Triassic reptiles can be used for paleogeographie reconstruction and stratigraphic correlation based on their wide distribution, great independence from the environment and rapid evolution.