New Tyrannosaur Discoveries Reveal Details about T. rex [Slide Show]
A flood of new tyrannosaur finds is helping to shed light on how their gargantuan successor developed
By Katherine Harmon
September 17, 2010
Tyrannosaurs emerged about 165 million years ago, during the middle Jurassic, about 100 million years before T. rex lived. The earliest tyrannosaurs were quite a bit smaller than the tremendous Tyrannosaurus rex, including many that were close to human size. Guanlong (seen here, an illustration of the Guanlong wucaii) lived some 160 million years ago and measured about three meters long. This unusual-looking dinosaur was in fact relatively typical for an early tyrannosaur in that its head was crowned by a large crest.
By examining many of the newly described species, scientists have learned that early tyrannosaurs were far from central figures in their ecosystems. Instead these dinosaurs inhabited fringe roles. Also, the comparison revealed that T. rex "is quite abnormal when compared with other members of the group," Stephen Brusatte, a graduate researcher with the American Museum of Natural History and co-author of the new Science paper that assessed a host of new discoveries about tyrannosaurs, said in a prepared statement.