Source: Xinhuanet

07-19-2007 19:34

Chinese archaeologists have discovered a the remains of gigantic bird-like dinosaur in the Gobi Desert in north China's Inner Mongolia Autonomous Region, which could overturn theories that dinosaurs became generally smaller as the evolved into birds.

BEIJING, June 14 (Xinhua) -- Chinese archaeologists have discovered a the remains of gigantic bird-like dinosaur in the Gobi Desert in north China's Inner Mongolia Autonomous Region, which could overturn theories that dinosaurs became generally smaller as the evolved into birds.

The animal, named gigantoraptor erlianensis, is believed to have been about eight meters in length, weighed 1,400 kg, and stood up to five meters high.

Chinese archaeologists said that despite its enormous size, gigantoraptor erlianensis belonged to the oviraptorosauria, a group of smaller, feathered animals.

In light of its size, the researchers performed two different tests to confirm that it belonged to the oviraptorosaur family.

"The analyses strongly supported the oviraptorosaur affinity ofgigantoraptor erlianensis and suggested this new dinosaur was in an intermediate position in oviraptorosaurian evolution," Xu Xing,a researcher with the Institute of Vertebrate Paleontology and Paleon anthropology with the Chinese Academy of Sciences.

Chinese archaeologists believe gigantoraptor erlianensis was an anomaly in the evolution of dinosaurs to birds and its discovery complicates the evolutionary pattern.

Xu said they had no direct evidence that gigantoraptor erlianensis was feathered like its close relatives, but based on its close relationship to other feathered species such as caudipteryx and protarchaeopteryx, gigantoraptor erlianensis probably had feathers on its arms and tail at least.

The largest known feathered animal so far is the 500-kg Stirton's thunder bird (dromornis stirtoni), which lived in Australia eight to six million years ago. Gigantoraptor erlianensis was about three times as heavy as dromornis stirtoni.

"Discovering such a big featured animal is beyond our imagination. It's like seeing a mouse as big as a pig," Xu said.

Researchers found that gigantoraptor erlianensis possessed many features unknown in other dinosaurs, such as highly specialized caudal vertebrae and the bizarre humerus, suggesting that morphological diversity among the dinosaurs is higher than previously known.

Xu said normally when dinosaurs become so large, they had proportionally stouter limbs and shorter lower legs than their smaller relatives. However, gigantoraptor erlianensis has much more slender limbs and longer lower legs than similarly-sized theropods, suggesting that it might have been adapted for running.