Evolution: A gigantic bird-like dinosaur

The remains of a gigantic, surprisingly bird-like dinosaur have been uncovered in Inner Mongolia, China. The animal — which lived in the Late Cretaceous (about 70 million years ago) — is thought to have had a body mass of about 1,400 kilograms, which is surprising as most theories suggest that carnivorous dinosaurs got smaller as they got more bird-like. The dinosaur has been classed as a new species and genus.
Xing Xu and colleagues carried out a phylogenetic analysis of the skeleton and have grouped the fossil with a family that included the beaked, bird-like Oviraptor because of its similarly avian features. What is most striking, however, is that at 1,400 kilograms the fossil is about 35-times heavier than other similar feathered dinosaurs, which rarely exceeded a body mass of 40 kilograms.
The authors estimate that the new dinosaur would have been about eight metres long and would have stood, at the shoulder, twice the height of a man. They suggest that a growth rate considerably faster than large North American tyrannosaurs contributed to this. The team also noticed lines of arrested growth on the fossil, indicating that it was still a young adult when it died, so the full-sized dinosaur may have been even larger than this. But, despite its great size, many features of its anatomy were more bird-like, rather than less, as would have been expected.
CONTACT
Xing Xu (Chinese Academy of Sciences, Beijing, China)
Tel: +86 10 8836 9196; E-mail: xu.xing@ivpp.ac.cn or xingxu@vip.sina.com