Move over Archaeopteryx, an older bird just landed on the evolutionary tree.

Scientists writing in Nature magazine, say a feathered, chicken-sized creature known as Aurornis xui, unearthed recently in northeastern China, challenges the "pivotal position of Archaeopteryx" — long regarded as the oldest bird.

Aurornis is dated to the Jurassic period, 160 million years ago and about 10 million years before Archaeopteryx makes its first known appearance in the fossil record.

"Our analyses indicate [Aurornis is] the most primitive bird known," co-author Andrea Cau, a vertebrate paleontologist at the Museo Geologico Giovanni Capellini in Italy, says. "It looked like a ground bird, but with a long tail, clawed hands and toothed jaws."

As The Los Angeles Times writes:

"The study authors argue that Aurornis represents the earliest known bird, but other scientists say it could be part of a group of bird-like dinosaurs that were developing feathers and bird-like features but never quite got off the ground, evolutionarily speaking.'You're looking at an animal that is either a very primitive bird or something very closely related to birds,' said [Luis] Chiappe, a veterbrate paleontologist at the National History Museum of Los Angeles who is not involved in the Nature study. 'I tend to think that it's not a bird, but that it's one of those true very close ancestors of bird.'"

The discovery is not all bad news for newly dethroned Archaeopteryx.

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