The Triassic period («triad» in Greek) — is the Mesozoic era period, between 250 and 202 million years ago. The name «three» was given because of Western European rock deposits backdated to that time, including shell-limestone, caper and sandstone.
Before the Triassic period, all continents formed a single giant continent called Pangea. Later it started to split, inland seas became shallower and arid areas expanded.
Soon after split, the great dinosaur age started. Argentina hosted most of early inhabitants: terrestrial Eoraptor, Coelophysis, and Plateosaurus, flying Eudimorphodon and Preondactylus. The primitive Archosaurs Desmatosuchus and Postosuchus were already on the brink of extinction. The huge aquatic Mastodontosaurus and Cryostega were also fading away.