Several recent fossil discoveries are used as proof that not all dinosaurs became extinct, but are the animals we call birds. The fossil findings of Caudipteryx zoui and Protarchaeopteryx robust from China are seen by some paleontologists as proof that birds not only descended from dinosaurs, but are dinosaurs. The remains of these two 120 million-year-old species were found in Liaoning Province in northeast China. Two fossils were Protarchaeopteryx robust, while a third was a Caudipteryx zoui.

Protarchaeopteryx robust fossils indicate this animal was a relative of Archaeopteryx lithographica; it was turkey-sized and covered with down-and quill-like feathers. The Caudipteryx zoui fossil remains show features of a theropod dinosaur, but it was also covered with down-and quill-like feathers. The wing feathers were not swept-back (as needed for flight), but were symmetrical in shape.

Both animals had the shape of swift, long-legged runners and, based on their skeletal characteristics, were more closely related to dinosaurs than birds. Even though they had feathers, neither appeared capable of flight. This seems to indicate that certain dinosaurs developed feathers for reasons other than flight. These feathered dinosaurs did not go extinct at the end of the Cretaceous period, and some scientists believe they continued to evolve into modern birds.