is one of the oldest known dinosaurs.
Scientists had expected such a dinosaur forerunner to be a smallish, two-legged predator resembling early dinosaurs such as Herrerasaurus
, which lived about 231 million years ago in Argentina.
They say the fossils, which were first unearthed in the 1930s in Tanzania, are those of a creature the size of a Labrador retriever, but with a five foot-long tail, that walked the Earth about 10 million years before more familiar dinosaurs like the small, swift-footed Eoraptor and Herrerasaurus
For instance, one of the Argentinean dinos, Herrerasaurus
, was a two-legged meat eater about the size of a crocodile.
Sereno's scientific expeditions started 22 years ago in the foothills of the Andes in Argentina, where he and his team of researchers uncovered what are believed to be among the first dinosaurs to roam the Earth, predators called Herrerasaurus
It is a gargantuan display, with authentic fossils and detailed casts spanning the era from Herrerasaurus
, one of the earliest dinosaurs, to the ferocious meat-eaters of the Late Cretaceous Period.
Retrospective permission to use the figures of Herrerasaurus
(Sereno and Novas, 1992) and Sinornis (Sereno and Rao, 1992) has now been given.
Carnivorous species like Tyrannosaurs were among the most "damaging, efficient" biters despite having less teeth, Herrerasaurus
, Carcharodontosaurus, and Ceratosaurus relied mainly on the back teeth to bite.
Based on these trends, the researchers proposed at the vertebrate paleontology meeting that Herrerasaurus
, an early predatory dinosaur with few neurovascular foramina, had lizard-like lips.
The oldest and most basal theropods, such as Eoraptor, Herrerasaurus
, and the ceratosaurs (e.g., Coelophysis, Syntarsus, Dilophosaurus), have relatively short, raptorial fore-limbs (Welles 1984; Gauthier 1986; Colbert 1989; Sereno 1993; Sereno et al.