1) Bird-footed dinosaur 2) Herrerasaur 3) Theropod 4) Theropod dinosaur 1) Herrerasaur 
For many years, the classification of Herrerasaurus was unclear because it was known from very fragmentary remains. It was hypothesized to be a basal theropod, a basal sauropodomorph, a basal saurischian, or not a dinosaur at all but another type of archosaur. However, with the discovery of an almost complete skeleton and skull in 1988, Herrerasau...
primitive carnivorous dinosaur or close relative of dinosaurs found as fossils in Argentine deposits from the Late Triassic Period (227 million to ...