World's First Bird: Evidence of a New Species Has Scientists Reconsidering the Evolutionary Development of Avian Creatures

For over 150 years, the Archaeopteryx has been thought to be the world's first bird, but now new evidence shows that may not be the case, and that a new species, Aurornis xui may actually be the first bird, according to National Geographic.

The new species was described by paleontologist Pascal Godefroit in the journal Nature. The finding includes fossil remnants of feathers and was discovered in the 160-million-year-old rock of China's Tiaojishan Formation. Aurornis is thought to have lived approximately 10 million years earlier than Archaeopteryrx, and far from the archipelago in Europe where it was found. However, the study did conclude that the two birds were close relatives at the base of bird evolution.

"It's among the earliest birds, being it's both older and apparently less 'bird-like' than Archaeopteryx along the 'bird branch,'" Andrea Cau, a co-author of the study from Italy's Museo Geologico, said.

The two birds share a close ancestral proximity, which counters a previous study that was published in Nature two years ago, which argued that Archaeopteryx and related dinosaurs were further removed from bird ancestry than the new study believes.

The researchers in the previous study thought that, in addition to Archaeopteryx, two other species fell outside the bird line and were more similar to a branch of non-bird dinosaurs called deinonychosaurs. That group includes feathery birds as well as the famous clawed dinosaur, the velociraptor.

Due to the recent discoveries of many bird-like species, there has been debate over what exactly makes a bird. Feathers alone don't do it, and scientists are trying to determine how to distinguish between the creatures that truly were prehistoric birds and those that are simply good candidates for archaic avian creatures.

"By being so primitive there is no definite way to place them as stem-birds, stem-deinonychosaurs," or members of another group, Thomas Holtz, Jr., a paleontologist at the University of Maryland, said. The animals are very close at the base of their lineage and separating them into which is a bird and which is not is a very difficult process.

"The problem we are facing these days is that all these animals are anatomically very similar, and our definition of birds, arbitrary as it is, sets a line between what is and what isn't called a bird," Luis Chiappe, a paleontologist at the Natural History Museum of Los Angeles, said.

Figuring out the evolutionary tree of birds will help historic scientists develop theories about how the first avian creatures evolved, as well as the origin of flight.