New Prehistoric Bird Species is Oldest Known Avian

The confirmation of a new species of prehistoric bird has generated a multi-pronged discovery: the new species is 10 million years older than Archaeopteryx, the creature previously considered the oldest bird known to science, the discovery reclassified a family of bird-like creatures as avian, and, perhaps most importantly, it ended all debate around whether Archaeopteryx should truly be considered avian.

About the size of a pheasant, the new species, named Aurornis xui, had a long tail and claws with legs similar to Archaeopteryx but some of its features were much more primitive. An absence of large feathers suggests the ancient bird was flightless.

"It's an important fossil," said Southampton University senior paleontologist Gareth Dyke, according to The Guardian. "Aurornis pushes Archaeopteryx off its perch as the oldest member of the bird lineage."

That the new species trumps Archaeopteryx as the oldest known bird is significant because when it was discovered in Germany in 1861, Archaeopteryx came to be seen as the first proof that birds evolved from dinosaurs and was the first fossil to support Darwin's theory of evolution, which was published around the same time, The Guardian reported.

In addition to Aurornis xui,a number of similar creatures discovered in the famous fossil beds of Liaoning Province, China, initially resulted in the demotion of Archaeopteryx from avian status to that of a bird-like dinosaur, a move that was contested because there was scientific consensus that Archaeopteryx could fly. "By re-classifying the animal it had implied also that powered flight must have evolved at least twice - once on the real line to birds and again in this parallel pool of dinosaurs that merely shared some bird features," wrote BBC science correspondent Jonathan Amos.

But discovery of Aurornis xui re-simplifies the understanding of how birds came to emerge from dinosaurs and how powered flight originated.

Archaeopteryx is again considered an ancestor of birds and the new creature we describe is also a basal bird; and in fact it is even more primitive than Archaeopteryx," Pascal Godefroit from the Royal Belgian Institute of Natural Sciences and lead author on the paper that describes Aurornis xui, told the BBC.

The discovery of Aurornis xui also reclassified the status of Troodontidae, a family of bird-like dinosaurs. Godefroit and colleagues now consider the Troodontidae to be a sister group of the avains.

"The new species is certainly an older member of the bird lineage than Archaeopteryx, and it's fair to call it a very primitive bird. But what you call a bird comes down to what you call a bird, and a lot of definitions depend on Archaeopteryx," Paul Barrett, of the Natural History Museum in London, told The Guardian.

Godefroit's study is published in the journal Nature.