The fossilised ‘Dawn bird’, Aurornis xui, lived 160m years ago and had downy feathers but was probably unable to fly

Aurornis xui ‘pushes Archaeopteryx off its perch’ as the oldest known member of the bird lineage. Photograph: Emiliano Troco

A prehistoric beast the size of a pheasant has become a contender for the title of oldest bird to stalk the Earth.

The small, feathered “Dawn” bird lived around 160m years ago, about 10m years before Archaeopteryx, which holds the official title of the earliest bird known to science.

The new species, which scientists have named Aurornis xui, had claws and a long tail, with front and hind legs similar to those of Archaeopteryx, but some features of its bones were more primitive. It measured 50cm from its beak to the tip of its tail.

Encased in sedimentary rock, the 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.

When scientists reconstructed the evolutionary tree of similar beasts using measurements from their skeletons, A xui appeared on the bird lineage, but closer to the base of the tree than Archaeopteryx.

“It’s an important fossil,” said Gareth Dyke, a senior palaeontologist involved in the study at Southampton University. “Aurornis pushes Archaeopteryx off its perch as the oldest member of the bird lineage.”

Archaeopteryx holds a prized position in evolutionary history. The fossil, discovered in Germany in 1861, proved that modern birds evolved from dinosaurs, and was the first fossil to support Darwin’s theory of evolution, which had been published only two years earlier.

Scientists bought the remains from a local fossil dealer, who claimed they had been unearthed in Yaoluguo in western Liaoning, China. Photograph: Thierry Hubin/IRSNB

Researchers named the new species Aurornis xui because it marks the earliest days of the evolutionary path that led to modern birds. Aurornis combines aurora, the Latin for dawn, and ornis, the Greek for bird. The second part of the name, xui, honours Xu Xing, a Chinese palaeontologist, according to a report in Nature.

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