A fossil of two Confuciusornis
The abundance of Confuciusornis at Liaoning is expected to eventually reveal a great deal about this stage in the evolutionary development of flight. For example, visible anatomical differences that reveal gender — sexual dimorphism — are common among dinosaurs. Confuciusornis is no exception as the males, who are larger than females, sport a pair of exceptionally long, narrow tail feathers.
THE GEOLOGICAL MUSEUM OF CHINA