Aurornis xui – New Candidate for Oldest Bird

A newly discovered bird-like dinosaur named Aurornis xui is about 10 million years older than Archaeopteryx, the feathered dinosaur previously considered the oldest bird known to paleontologists.

Reconstruction of Aurornis xui (Emiliano Troco)

Reconstruction of Aurornis xui (Emiliano Troco)

“It’s an important fossil. Aurornis pushes Archaeopteryx off its perch as the oldest member of the bird lineage,” said Dr Gareth Dyke from the University of Southampton’s Ocean and Earth Science, senior author of the study published in the journal Nature.

Aurornis xui lived during the Middle-Late Jurassic period around 160 million years ago. It was about 50 cm from its beak to the tip of its tail – the size of a pheasant. It had a long tail and claws with legs similar to Archaeopteryx but some of its features were much more primitive.

Encased in sedimentary rock, the Aurornis fossil preserved traces of downy feathers along the animal’s tail, neck and chest, but the absence of larger feathers suggests it was not able to fly.

The generic name Aurornis is derived from the Latin word aurora, meaning ‘daybreak,’ and the Greek word ornis for ‘bird.’ The specific name xui honors the paleontologist Xu Xing.

Aurornis fossil (Pascal Godefroit et al)

Aurornis fossil (Pascal Godefroit et al)

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.

“With the find of Aurornis xui, 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,” explained study lead author Dr Pascal Godefroit of the Royal Belgian Institute of Natural Sciences.

The Aurornis discovery also reclassified the status of Troodontidae, a family of bird-like dinosaurs. Paleontologists now consider this dinosaur family to be a sister group of the avians.

“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,” said study co-author Dr Paul Barrett from the Natural History Museum in London, UK.

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Bibliographic information: Pascal Godefroit et al. A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds. Nature, published online May 29, 2013; doi: 10.1038/nature12168