If it really is a single animal and not a chimera, "Protoavis" would raise questions about when birds began to diverge from the dinosaurs, but until better evidence is produced, the animal's status currently remains uncertain. Furthermore, paleobiogeography suggests that true birds did not colonize the Americas until the Cretaceous; the most primitive lineages of unequivocal birds found to date are all Eurasian. Certainly, the fossils are most parsimoniously attributed to primitive dinosaurian and other reptiles as outlined above. However, coelurosaurs and ceratosaurs are in any case not too distantly related to the ancestors of birds and in some aspects of the skeleton not unlike them, explaining how their fossils could be mistaken as avian. Palaeontologist Zhonghe Zhou stated: