Early archaeological study has shown that in their evolution into birds, dinosaurs become smaller in size and within each dinosaur group smaller species are normally more bird-like than their larger relatives.

But Chinese archaeologists said gigantoraptor erlianensis is more bird-like than its small relatives in many features such as a longer arm and a more bird-like leg.

"This suggests that there are different underlying mechanisms along the line to birds in theropod evolution," Xu said.

Chinese researchers also found that the one-and-half-tone gigantoraptor erlianensis had no teeth, but was beaked dinosaur.

Gigantoraptor's diet remains unknown, but it shows both herbivorous features (such as small head and long neck) and carnivorous features (such as sharp claws).

Other oviraptorosaurs are believed to have been plant-eaters, egg-eaters, mollusc-eaters, and meat-eaters according to various studies.

Researchers deducted that the animal probably died in its 11th year based on the growth lines preserved in the fibular bone.

They also inferred that the animal reached maturity within seven years and was still relatively young at the time of death.

The bird-like dinosaur fossil was discovered in 2005 at Erlian Basin, known for its dinosaur fossils and other vertebrate fossils.

The dissertation on gigantoraptor erlianensis will be publishedon Nature on June 14.

Editor:Chen Ge