1. National Geological Museum of China , Yangrou Hutong 15, Xisi, 100034 Beijing, People's Republic of China
2. Royal Tyrrell Museum of Palaeontology , Box 7500, Drumheller, Alberta T0J 0Y0, Canada
3. American Museum of Natural History , Central Park West at 79th Street, New York, New York 10024-5192, USA

Correspondence to: Philip J. Currie² Correspondence and requests for materials should be addressed to P.J.C. (e-mail: Email: pcurrie@mcd.gov.ab.ca).

Abstract

Current controversy over the origin and early evolution of birds centres on whether or not they are derived from coelurosaurian theropod dinosaurs. Here we describe two theropods from the Upper Jurassic/Lower Cretaceous Chaomidianzi Formation of Liaoning province, China. Although both theropods have feathers, it is likely that neither was able to fly. Phylogenetic analysis indicates that they are both more primitive than the earliest known avialan (bird), Archaeopteryx. These new fossils represent stages in the evolution of birds from feathered, ground-living, bipedal dinosaurs.

1. National Geological Museum of China , Yangrou Hutong 15, Xisi, 100034 Beijing, People's Republic of China
2. Royal Tyrrell Museum of Palaeontology , Box 7500, Drumheller, Alberta T0J 0Y0, Canada
3. American Museum of Natural History , Central Park West at 79th Street, New York, New York 10024-5192, USA

Correspondence to: Philip J. Currie² Correspondence and requests for materials should be addressed to P.J.C. (e-mail: Email: pcurrie@mcd.gov.ab.ca).