Feathers are an unmistakable trait of birds, and the relative lack of fossils showing the origin and evolution of feathers has driven much of the debate over bird origins. A turkey-sized dinosaur named Sinosauropteryx and another find dubbed Protarchaeopteryx, were described by Ji Qiang and Ji Shu'an of the National Geological Museum of China in two reports . These fossils were found in Liaoning province in strata dating to the late Jurassic or early Cretaceous. Sinosauropteryx has fringed elements along its backbone and body surface which may be feather precursors.
It does, however, have many differences with birds and probably is related to the theropod Compsognathus. This finding may be either a maniraptoran theropod or possibly a bird, but a full description of its anatomy still awaits publication . Hou and colleagues (1995) have reported the finding of Confuciusornis sanctus, a pigeon-sized specimen from a formation in northeastern China dated to the Jurassic-Cretaceous boundary. This species may have lived before Archaeopteryx, but exhibits the hindlimbs and retroverted pubis similar to Archaeopteryx. The skeleton also has unfused carpal elements and long fingers with long, curved claws (Hou et al, 1995). There also exist avian-like contour feathers, which could indicate endothermic physiology.