Mid-Triassic – 231.4 Mya
South America: Argentina
Length: 4.6 meters (15 feet)
Height: 2.1 meters (7 feet)
Weight: 210–350 kg (463–772 lb)
With the discovery of an almost complete skeleton and skull in 1988 the small, lightly built Herrerasaurus was finally determined to be either a very early theropod or early saurischian (lizard-hipped dinosaur). But its pubis is very much like the pelvis of later ornithischians including hadrosaurs, ceratopsians and ankylosaurs. Herrerasaurus may be close to the ancestry of several major groups of dinosaurs.
This mid-Triassic dinosaur first appeared in a time when dinosaurs were not yet dominant and competed against larger, more powerful animals for food. It most likely captured small animals, including other smaller dinosaurs, through ambush and surprise.