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Vendredi, 01 Juillet 2011 16:00

X-rays Reveal Colors of First Birds

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X-rays Reveal Colors of First Birds

By Mark Brown, Wired UK

Confuciusornis sanctus, a prehistoric beaked bird which co-existed with dinosaurs some 120 million years ago, had a dark body, neck and tail, and impressive patterns along its feathers.

We know that, in remarkable detail, because a team of paleontologists from California and Manchester have used innovative x-ray techniques to get an close look at the shades and patterns of the ancient bird’s plumage.

The team used equipment at the Department of Energy’s SLAC National Accelerator Laboratory to map the chemical traces of eumelanin — a colouring agent responsible for brown eyes and dark hair in many species — in well preserved fossils of two ancient birds.

Those were Confuciusornis sanctus and the 100 million year oldGansus yumenensis, which is considered the oldest modern bird.

To find this pigment the team looked for residue of trace metals like copper, nickel, zinc and iron, because the atoms of those elements are often incorporated into eumelanin.

By taking one of those metals — in this case, copper — and mapping its distribution across the bird, the paleontologists were left with an incredible representation of how dark or how light the eumelanin was, the different patterns it produced and where it was most prominent.

The researchers did the same study on modern feathers and even squid, and saw how accurately the copper matched up with the animals’ patterns.

Unfortunately, with eumelanin only used for dark brown and black pigmentation, the researchers haven’t cracked color, yet. “If we could eventually give colors to long extinct species, that in itself would be fantastic,” said Uwe Bergmann, from the SLAC National Accelerator Laboratory, in a press release.

Nevertheless, the discovery is already rewriting the history books. “One of the reviewers of our article pointed out that a recently published book on [Confuciusornis] has now to be rewritten because the shading we find in our study doesn’t agree with what was depicted in that book,” said Bergmann.

“These new techniques for teasing out evidence of pigmentation will take a lot of the guesswork out of reconstructing the appearance of extinct dinosaurs and birds,” said Dinotopia illustrator James Gurney in the release.

As well as making movies, dioramas and textbook illustrations more realistic, the discovery will give paleontologists more information on the ways these birds used camouflage, communicated and selected mates.

Image: Drawing of C. sanctus. (Gregory Stewart/SLAC National Accelerator Laboratory)

Video: StanfordUniversity/YouTube

Source: Wired.co.uk

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