Caudipteryx zoui, is a close relative of  birds. Caudipteryx shows besides some diferences also many similaritys with the family oviratorosauridae.The hind legs are in both animals extremely long which can be seen as a indication that this where fast running animals. 

According to Norell the fossils are considered theropod dinosaurs rather than true birds because they lack a number of features seen in Archaeopteryx and more advanced birds. He and his colleagues doubt that the creatures could fly because they had relatively short forelimbs, short feathers, and a body twice the size of Archaeopteryx. Whats more, their feathers had a symmetrical shape like that seen in flightless birds today.