Feathered dinosaur's full plumage unveiled

Paleontologists have revealed the detailed colour pattern of the feathers of a four-winged dinosaur that lived more than 150 million years ago.

The dinosaur, Anchiornis huxleyi, had a dark grey or black body, long white feathers fringed with black on its wings, and a long reddish-brown crest on its head and matching speckles on its face, the scientists said.

"This was no crow or sparrow, but a creature with a very notable plumage," said Richard O. Prum, a biologist at Yale University and a co-author of the study. "This would be a very striking animal if it was alive today."

The research, published online this week in Science Express, was done in a similar way to the study published in Nature last week that revealed the orange-and-white pattern of feather-like bristles on the tail of a small two-legged dinosaur.

The Yale scientists say their study is different because it analyzed the melanosomes, microscopic structures that carry pigment, of an entire fossil, and assigned colours to individual feathers.

The team of scientists which included scientists from the University of Texas at Austin, the University of Akron, Peking University and the Beijing Museum of Natural History used scanning electron microscopes to examine 29 fossil feather samples from the dinosaur.

They found microscopic fossils indicating the type of melanosomes that were present in the feathers, and even at different locations on individual feathers.

The shape of the melanosomes offers a clue to their colour: in modern birds and mammals, sausage-shaped melanosomes carry black and grey pigments and spherical ones carry orange and brown colours.

Some of the feather fossils contained no evidence of melanosomes and were probably white.

The researchers found that the colour pattern on Anchiornis huxleyi was similar to ones found in living birds, including domesticated waterfowl and the spangled Hamburg chicken.

The dinosaur wasn't capable of powered flight, so the researchers say their study is further evidence that feathers first evolved for other purposes.

"This means a colour-patterning function for example, camouflage or display must have had a key role in the early evolution of feathers in dinosaurs, and was just as important as evolving flight or improved aerodynamic function," said Julia Clarke of the University of Texas at Austin, in a statement.

For Prum, an ornithologist by training, the discovery of the colour pattern on the feathers of this dinosaur was especially interesting.

"Writing the first scientifically based 'field guide' description of the appearance of an extinct dinosaur was a exciting and unforgettable experience the ultimate dream of every kid who was ever obsessed with dinosaurs," Prum said.