Source: China Daily

07-23-2007 17:25

The remains of a giant, birdlike dinosaur as tall as the formidable tyrannosaur have been found in China, a surprising discovery that indicates a more complicated evolutionary process for birds than originally thought, scientists said Wednesday.

Fossilized bones uncovered in the Erlian Basin of northern China's Inner Mongolia region show that the specimen was about 26 feet long, 16 feet tall and weighed 3,000 pounds, said Xu Xing, a paleontologist at the Institute of Vertebrate Paleontology & Paleoanthropology in Beijing.

The height is comparable to the meat-eating tyrannosaurs. But the dinosaur, called Gigantoraptor elrianensis, also had a beak and slender legs and likely had feathers. It was 35 times larger than its likely close relation, the Caudiperyx, a small, feathered dinosaur species, Xu said.

That puts the Gigantoraptor's existence at odds with prevailing theories that dinosaurs became smaller as they evolved into birds and that bigger dinosaurs had less birdlike characteristics, he said.

"This is like having a mouse that is the size of a horse or cow," said Xu, who co-authored a paper on the finding published Thursday in the journal Nature. "It is very important information for us in our efforts to trace the evolution process of dinosaurs to birds. It's more complicated than we imagined."

The Caudiperyx and the Gigantoraptor belong to a group of dinosaurs called oviraptors, which tend to be human-sized or smaller. In recent years paleontologists have found turkey-sized, feathered representatives of the group, but they have never found anything close to the scale of Gigantoraptor.