A three-meter long carnivore living around 160 million years ago has been identified as the earliest known member of the fierce Tyrannosaurus rex (T.rex) family, Chinese and U.S. scientists reported on Wednesday.
The finding, filling a big blank about tyrannosaurus, appeared in the Feb. 9 issue of the journal Nature. The first author of the paper, Xing Xu, is a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.
The new species, found in Xinjiang in northwestern China, was identified as the most primitive known member of the tyrannosaurus family. The creature is a significantly smaller relative of T. rex, which could reach a towering 13 meters.
But its gaping, beak-like face armed with teeth, and its powerful legs, show that it would also have been a killer. The researchers named it Guanlong wucaii, meaning "crested dragon with five colors."
The name came from the huge nasal crest on the creature's head, and the fact that it was found in a region of China characterized by many-colored rocks.
"G. wucaii is the oldest known tyrannosauroid and shows several unexpectedly primitive pelvic features. Nevertheless, the limbs of G. wucaii share several features with derived coelurosaurs and it possesses features shared by other coelurosaurian clades," the researchers said.
"This unusual combination of character states provides an insight into the poorly known early radiation of the Coelurosauria," they wrote in the Nature paper.
Dinosaur specimens of this vintage are rare, with most other Jurassic dinosaur fossils having been unearthed in America.
The presence of a nasal crest is particularly interesting, according to the researchers, because it is so similar to the head ornaments carried by many of today's birds. The finding further supports the theory that birds and carnivorous dinosaurs such as tyrannosaurus belong to one evolutionary family.
"Notably, the presumed predatory Guanlong has a large, fragile and highly pneumatic cranial crest that is among the most elaborate known in any non-avian dinosaur and could be comparable to some classical exaggerated ornamental traits among vertebrates, " the researchers said.
The paper-thin crest of G. wucaii probably functioned as a signal, either to attract potential mates or for species recognition, the researchers said.
If it was a sexual ornament, it might imply that this individual was a male. But if it was for species recognition, that would leave the dinosaur's sex for further study, they noted.