Sinosauropteryx prima (Ji and Ji 1996; Early Cretaceous, Yixian Formation) is considered to have very primitive feathers, but the large reptile tree indicates this plummage is reduced from more elaborate feathers found in earlier Archaeopteryx and contemporaneous Microraptor. Sinosauropteryx nests with Juravenator in the large reptile tree.
The rostrum is relatively short. The dorsal vertebrae are robust. The tail is quite long and gracile. The humerus is short. The elbow (ulna) and manual digit 1 are both robust. The hind limbs are shorter, but more robust.