The oldest dinosaur fossil ever found dates back around 230 million years. But the fossils of around a dozen specimens of a new animal called Asilisaurus kongwe, or silesaur, found in Tanzania lead researchers to believe dinosaurs diverged from another evolutionary line around 243 million years ago.
“Back then it was a very large river system, maybe something like the Mississippi today,” said lead author and University of Texas at Austin paleontologist Sterling Nesbitt. During that time, Africa, South America, Antarctica, Australia and India were all one giant continent called Gondwana.
Though silesaurs are very closely related to dinosaurs, they lack the open hip-sockets that are universal in dinosaurs. The Asilisaurus was a small, four-legged creatures with a long tail. Their beak-like jaws and leaf-shaped teeth helped the animals eat the soft, fibrous leaves of the primordial palms, ferns and conifers that were prevalent during the Triassic period. That suggests that, while the animal may not have been exclusively vegetarian, a good portion of its diet came from plants, he said.
The silesaur changes the conventional wisdom that the dinosaur's closest relatives were predators. Link