TAIL FEATHER
Of all China's amazing non-bird dinosaurs and birds, none has proven more astonishing than Caudipteryx ("tail feather"). This long-legged, turkey-sized creature seems a mixture of both kinds of animal, with a bird-like beak, feathers and short-tail, but teeth and bones that proclaim it a non-bird theropod dinosaur. Caudipteryx lived in Early Cretaceous times, not long after the first known bird. Scientists have suggested it might have been either a strange theropod dinosaur, a theropod dinosaur with ancestors that flew, or a bird that evolved from birds that had lost the power to fly. It is most probable that Caudipteryx was a dinosaur, and the maniraptoran ("grasping hand") and oviraptorid dinosaurs were its nearest relatives.

Feather function
Feathers of different kinds covered most of Caudipteryx. Short down provided insulation, and implied that Caudipteryx was warm-blooded. Feathers with 20 cm (8-in) long quill shafts sprouted from its arms, fingers, and tail, but Caudipteryx could not fly. Its wing feathers were symmetrical, whereas the wing feathers found in birds that can fly are asymmetrical. Caudipteryx's feathers might have been brightly coloured and used for mating displays.

Puzzling relationships
Scientists stressing Caudipteryx's bird-like nature have claimed it had a reversed "big" toe, and used muscles like a bird's to pull back its legs as it walked. Other scientists believe both suppositions unproved, and stress details indicating that this was a non-bird dinosaur. For instance, the pubic hip bones pointed forwards, while the beak, tail bones, and other hip bones hint that Caudipteryx was closely related to the dinosaur Oviraptor.