Four-winged dino may be missing link in bird debate

By | September 26, 2009

Feathered dinosaur (Xing Xu)The stunning remains of a “four-winged” dinosaur have confirmed that birds owe their ancestry to two-footed dinosaurs that lived millions of years ago, the world’s most famous fossil-hunter said.

Xing Xu of the Chinese Academy of Science in Beijing is staking the claim thanks to an astonishingly-preserved fossil of a bird-like dinosaur called Anchiornis huxleyi.

Until now, A. huxleyi was thought to be a primitive bird. It was presumed to have been a near-contemporary of Archaeopteryx, the first recognised bird, which flew around 150 million years ago.

But these opinions were based on an incomplete fossil.

The new, nearly-complete specimen gives a different picture, suggesting that A. huxleyi is millions of years older than Archaeopteryx and has both dinosaur and avian features.

It is the long-sought evidence that proves birds descended from theropod dinosaurs, argues Xu.

His team, whose work was announced late Thursday by the British journal Nature, describe a dinosaur with long feathers covering its arms, tail as well as its feet.

This is an arrangement that Xu says is “four-winged”, although no guarantee that the creature had aerial ability. In contrast, its elongated lower legs suggest it was a good runner.

Some evolutionary biologists have suggested that a four-winged condition played a role in the origin of flight, but the idea is opposed by others.

The plumage attachment is especially important because it shows how bird-like dinosaurs developed skeletal and other features enabling them to have feathers, the paper says.

via Four-winged dino may be missing link in bird debate – Yahoo! News.

An artist's impression of how these creatures  may have lookedExceptionally well preserved dinosaur fossils uncovered in north-eastern China display the earliest known feathers.

The creatures are all more than 150 million years old.

The new finds are indisputably older than Archaeopteryx, the “oldest bird” recognised by science.

Professor Xu Xing and colleagues tell the journal Nature that this represents the final proof that dinosaurs were ancestral to birds.

The theory that birds evolved from dinosaurs has always been troubled by the absence of feathers more ancient than those on the famous Archaeopteryx.

This has given critics room to question the idea.

But the new fossils, which come from two separate locations, are in most cases about 10 million years older than the primitive Archaeopteryx discovered in the late 19th Century.

One of the new dinosaur specimens, named Anchiornis huxleyi, is spectacular in its preservation.

It has extensive plumage covering its arms and tail, and also its feet – a “four-winged” arrangement, says Professor Xu from the Chinese Academy of Science in Beijing. …

– via bbc

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