By Seth Borenstein
Washington - Scientists have for the first time confirmed colour in a dinosaur. It is reddish-orange.
The first solid proof of pigmentation has been spotted in the fossilised tail feathers of a smallish meat-eating dinosaur found in China and named Sinosauropteryx. The creature seems to have russet-coloured rings, according to a paper published online on Wednesday in the journal Nature.
That 125-million-year-old tail has the same internal cellular colouring agents as the hair of a red-haired person, said study lead author Mike Benton, a professor of paleontology at the University of Bristol in England. And the same finding provides what some outside experts say is even more conclusive evidence that some dinosaurs had feathers, further linking them to birds.
Benton and his colleagues did not actually see the reddish colour itself. Using an electron microscope, they spotted the specific cellular signs of the colour. An earlier study by another group of researchers and Benton's team found similar cellular colour hints in prehistoric bird feathers.
Drawings of dinosaurs show them in all sorts of hues, usually duller Earth tones such as brown and grey, but scientists have only speculated on their colouring. As their connection to birds became known, so did the idea of brighter colours. But until now, there was no proof of any colouring.
Before Benton's technique, which is likely to be copied with other dinosaur fossils, paleontologists had to look to a dinosaur's anatomy to guess at colours, said famed dinosaur expert Paul Sereno at the University of Chicago. The colour and the feathers were probably used for display, like a peacock, he theorised. Sereno, who wasn't part of Benton's team, called it a "landmark paper" that gives us "a sneak peek at how they might have appeared when alive".
"That's really cool just to be able to pin down this aspect," said University of Maryland paleontologist Thomas Holtz Junior, who was not part of the discovery team. "It does sort of help bring a more complete view of the living creature and further from just being a bunch of bones."
This dinosaur was "a dinky little guy", Holtz said. Adult Sinosauropteryx were about three feet (one meter) long, but the tail accounted for more than half of that length and it had a long neck, so "there's not a lot of dinosaur there," he said. It fed on small mammals, sort of like a prehistoric roadrunner, he said.
While some dinosaurs are rather closely connected to birds evolutionarily, Sinosauropteryx is not. It was around earlier than the beginnings of birds and is the "most primitive feathered" dinosaur, Benton said. And those feathers, early in their evolutionary development, resemble tiny bristles, less than one-fifth of an inch tall, he said.
"They are stuffed with melanosomes just like any other feathers," Benton said. Melanosomes are molecules that contain colour-producing pigments. With the pigment long gone in fossils, the shape of the melanosome shows what colour it used to be. Sinosauropteryx had sphere-shaped melanosomes which translate to red, and sausage-shaped ones which are whitish-grey.
He and other researchers say the findings also strongly suggest these are feathers and not cartilage or some other tissue. Benton said it disproves the concept that the material is bacteria, a theory floated by a handful of scientists who still disagree with the mainstream view that dinosaurs had feathers.
One of those feather sceptics, John Feduccia at the University of North Carolina, was not convinced by the Benton study. He said the melanosomes are not similar to those of other animals and doesn't disprove the bacteria concept.
"Many people want dinosaurs to be feathered, so evidence is typically stretched beyond its content," Feduccia said in an email. "There is a strong lure to be able to vicariously study dinosaurs at the backyard bird feeder."
However, Sereno said Benton's research makes the case that colour cells couldn't be bacteria because they are packed orderly instead of randomly.
The idea of feathers on dinosaurs and the link to birds "is pretty much, I think, a done deal", Sereno said. - Sapa-AP