Wikipedia
Yandangornis is a genus of primitive bird (or possibly non- avialan theropod) from the Late Cretaceous. It lived 85 million years ago in what is now China. The type species, Y. longicaudus, was formally described by Cai and Zhou in 1999. The holotype specimen is in the collection of the Zhejiang Museum of natural History, with accession number M1236. The fossil was discovered in 1986, near Linhai City in Zhejiang Province, China. It includes most of one complete skeleton.
The specimen is small, roughly the size of Archaeopteryx, with a total length around . The head is long. It is preserved in a seated position and visible from the ventral aspect. It has a long tail. It has no teeth and no enlarged 2nd toe claw.
Cai and Zhao noted some features of Yandangornis that are more primitive than Archaeopteryx, and some, like toothlessness, that could be more derived.
Zhou and Zhang, 2007, reviewed the specimen and concluded that it lacks the diagnostic characters of birds, and that thus may to be a non-avian dinosaur.