Xu Xing and his colleagues from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing uncovered two specimens of the beast--a fully grown 12-year-old and a still-developing six-year-old--in the multi-hued rocks of the Junggar Basin in Xinjiang. These rocks date back to the end of the Jurassic era, roughly 160 million years ago. Based on the presence of such characteristics as fused nasal bones and U-shaped teeth in the front of the upper jaw, the researchers were able to identify the creature as a tyrannosaur. And its three-fingered hand, among other primitive traits, indicates that it was an early member of this family.
Its crest is a particularly spectacular example of the snout decorations common to tyrannosaurids. The function of the crest is unknkown, however. "It seems paradoxical that this predatory [group of animals] possessed a seemingly delicate, highly pneumatized cranial crest," Xing's team writes in its report on the findings, published today in Nature. The researchers suggest that it may have served to attract mates, much as the antlers of elk and the tails of peacocks do.
But the crested tyrannosaur also shares some features with small and swift coelurosaurs, lending even more credence to the theory that T. rex evolved from that diminutive group of predators rather than larger carnosaurs like Allosaurus. And although Guanlong was too small to be the top predator of its era, its descendant T. rex, which stood as much as 13 meters high, certainly reigned supreme during its day, despite lacking an awe-inspiring crown.