Oldest Known Dinosaur Relative Discovered

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Scientists have discovered a very close relative of the first true Dinosaurs in Tanzania Africa. Asilisaurus kongwe, a proto-dinosaur belonging to the newly named group silesaurs, lived abouut 10 million years before the appearance of its famous cousins in the Mid Triassic. Unexpectedly, unlike the earliest dinosaurs who were small, two legged carniverous animals, it appears to have been a herbivorous, four legged one.



(The sail‑backed archosaur Hypselorhachis is the animal in the background)

http://www.sciencedaily.com/releases/2010/03/100303131530.htm

Asilisaurus kongwe is part of a newly recognized group known as silesaurs. "We knew that there were a number of species from the Triassic that were similar to Asilisaurus," said Irmis, "but we were only able to recognize that they formed this group called silesaurs with the new anatomical information from Asilisaurus." Members of the silesaur group were distributed across the globe during the Triassic, when all of the continents were together in a supercontinent called Pangaea.

Silesaurs are the closest relatives of dinosaurs, analogous to the close relationship of humans and chimps. Even though the oldest dinosaurs discovered so far are only 230 million years old, the presence of their closest relatives 10 million to 15 million years earlier implies that silesaurs and the dinosaur lineage had already diverged from a common ancestor by 245 million years ago. Silesaurs continued to live side by side with early dinosaurs throughout much of the Triassic Period (between about 250 million and 200 million years ago). The researchers conclude that other relatives of dinosaurs, such as pterosaurs (flying reptiles) and small forms called lagerpetids, might have also originated much earlier than previously thought.