Herrerasaurus, the clade's type species

Herrerasauria is a clade of early theropod dinosaur, that were also ancestors of all dinosaur groups later. Herrerasauria are, in fact, the oldest dinosaurs known, that appeared in South America, roughly 230 million years ago (in the late Triassic), and lasted until the very end of the same era.

The type species of the Herrerasauria is the theropod Herrerasaurus ischigualastensis, the clade's biggest member.


Herrerasaurs were bipedal, carnivorous dinosaurs. They were only small dinosaurs, not passing over the lenght of 16ft (or 5m), and, being such primordial theropods, they had very primitive and unusual characteristics, like a partly open Acetabulum, and only two sacral vertebrae. Furthermore, the pubic bone was rotated posteriorly, the hand were primitive, having 5 fingers, the third finger being longer than the second.