A group of researchers from the Institute of Paleontology and Paleoanthropology of the Vertebrates of Beijing, Archaeopteryx, has proposed to remove from this position a group that has long been considered pioneer of birds. In the review of the characteristics of Archaeopteryx fossils and their comparison with other fossils found in recent times, the need to change their location has been seen.
Archaeopteryx was the first fossil discovered with strong anterior feathers and tips. The fossil also looked like a dinosaur, so it was considered as an intermediate group in the evolution of dinosaurs and birds. However, in recent years more fossils of these characteristics have been found, and hence the doubt arises of what would be the true ancestors of the birds and the members of a line that accompanies them.
The fossil that has pushed this last revision has been one of those found in the province of Liaoning in northwest China: It has been discovered in rocks of 161-145 million years (upper Jurassic) and belongs to the species Xiaotingia zhengi. This species also had feathers, but they have come to the conclusion that it belonged to the group of dinosaurs Deinonychosauria and not to the group of birds (Avialae). And they have seen that it has many common features with Archaeopteryx. Therefore, it has also been proposed to classify Archaeopteryx in this group. Among other things, the individuals of both groups had the flat end and the back of the extended buttonholes. For their part, the skulls of the ancestors of the birds were very different.