Plateosaurus was a Prosauropod Dinosaur that lived in the Late Triassic. It ate plants and was one of the first large dinosaurs to walk the earth. New Blood, scaring away some Coelophysis. They are some of the first truly massive Dinosaurs, and were the precursor to the later rule of even larger herbivores. It is important to note however, that many people mistakenly think that Plateosaurus gave rise to the Sauropods. As it happens, the Prosauropod suborder of which Plateosaurus is a key member, is just a forerunning group of large herbivores of the Saurischian (lizard-hipped) Order that includes Sauropodamorphs (Prosauropods and Sauropods) and all Theropods collectively. They are in a sense the Triassic prototypes that are made redundant in the Jurassic by the separate evolution of the 'new model' Sauropoda Sauropodomorphs. Prosauropods were in a sense, cousins that came first, but died as the newcomers took over their roles. Plateosaurus lived from the Norian Stage of the Triassic Period, but along with all Prosauropods became extinct entirely relatively shortly after the end of the Triassic Period during the Early Jurassic Period.