This feature supports the idea that the evolution of flight involved a four-winged stage. Here we describe a fossil of an enanti-ornithine bird from the Early Cretaceous period in China that has substantial plumage feathers attached to its upper leg(tibiotarsus). The discovery could be important in view of the relative length and aerodynamic features of these leg feathers compared with those of the small 'four-winged' gliding dinosaur Microraptor and of the earliest known bird, Archaeopteryx. Theymay be remnants of earlier long, aerodynamic leg feathers, in keeping with the hypothesis that birds went through a four-winged stage during the evolution of flight.
展开▼
