Scientists say they've found the earliest known tyrannosaur, shedding light on the lineage that produced the fearsome Tyrannosaurus rex. The discovery comes with a puzzle: Why did this beast have a strange crest on its head?
Digging in the badlands of northwestern China that appeared in the movie "Crouching Tiger, Hidden Dragon," researchers found two skeletons of 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, the beast was far smaller than T. rex, 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 Thursday's issue of the journal Nature.
The big 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.
Nobody knows its purpose, but it was probably some kind of display to other members of its own species, said Clark, co-leader of 2002 expedition that found the beast.
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 multi-hued 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.
By Malcolm Ritter