Scientists find early ancestor of T. rex

NEW YORK -- Digging near Chinese badlands that appeared in the movie "Crouching Tiger, Hidden Dragon," scientists have found their own hidden dragon: the oldest known tyrannosaur, a primitive ancestor of the fearsome Tyrannosaurus rex.

The two skeletons they unearthed shed light on the lineage that produced T. rex, revealing a creature that lived some 160 million years ago. That's more than 90 million years before T. rex came along.

A two-legged meat-eater with a puzzling crest on its head, the beast was far smaller than its celebrity descendant, measuring about 10 feet from its snout to the tip of its tail and standing about 3 feet tall at the hip. It also sported relatively long, three-fingered arms, rather than the two-fingered stubby arms T. rex had. Scientists suspect it had feathers because related dinosaurs did.

The discovery is reported in today's issue of the journal Nature.

The surprise, said study co-author James Clark of George Washington University in Washington, D.C., was the finding of a narrow, delicate, largely hollow crest on its head. While other dinosaurs have had similar features, this one was unusually large and elaborate for a two-legged meat-eater, Clark and co-authors wrote.

The researchers named the creature Guanlong wucaii, from the Chinese words for "crown" and "dragon," referring to the crest, and for "five colors," from the badlands where the creature was found.

Because it preserves anatomical features from its ancestors that were lost in T. rex and other tyrannosaurs, the primitive beast helps scientists understand where tyrannosaurs fit in the evolutionary tree, said an expert not involved in the discovery.

"This is the best look so far at the ancestral condition from which the tyrant dinosaurs, T. rex and company, evolved," said the expert, Thomas Holtz Jr. of the University of Maryland.

Along with some other finds, the creature helps illustrate the sequence of anatomical changes that occurred along the way to the later, more specialized tyrannosaurs, said Philip Currie of the University of Alberta in Canada.

Ken Carpenter, curator of lower vertebrate paleontology at the Denver Museum of Nature and Science, said he tentatively accepts the creature as a tyrannosaur but isn't convinced of its age. It could be much younger, he said. Clark said that other data, not yet published, support the proposed age of 160 million years.

On the Net

Nature: www.nature.com/nature

Background on tyrannosaurs:

www.ucmp.berkeley.edu/diapsids/saurischia/tyrannosauridae.html