By Carl Zimmer
New York Times / January 28, 2010
Dino tail feathers were carrot colored, study says.
That is what a team of Chinese and British scientists reported yesterday in Nature, providing the first clear evidence of dinosaur colors from studies of 125-million-year-old fossils of a Sinosauropteryx.
“We might be able to start painting a picture in color of what these things looked like,’’ said Lawrence M. Witmer, a paleontologist at Ohio University who was not involved in the study.
Of course, such pictures have been painted many times, but the colors were products of a painter’s imagination, not a scientist’s laboratory.
Dinosaur fossils are mostly drab collections of mineralized bones. A few preserve traces of skin, and fewer still preserve structures that many scientists have argued are feathers.
In the new study, Michael Benton, a paleontologist at the University of Bristol, and colleagues have analyzed the structures of what appear to be feathers and say they match the feathers of living birds down to the microscopic level. And they used those microscopic features to determine what color the ancient feathers were.
The study builds on earlier work on fossil bird feathers by Jakob Vinther, a graduate student at Yale, and his colleagues. In 2006, Vinther discovered what looked like an ink sack preserved in a squid fossil. Putting the fossil under a microscope, he discovered the sack was filled with tiny spheres. The spheres were identical to pigment-loaded structures in squid ink, known as melanosomes.
Vinther knew that melanosomes created colors in other animals, including bird feathers. He and his colleagues made a microscopic inspection of fossils of feathers from extinct birds. They discovered melanosomes with the same sausage-shaped structure of those found in living birds. By analyzing the shape and arrangement of the fossil melanosomes, they were able to get clues to their original color. They determined, for example, that a 47-million-year-old feather had the dark iridescent sheen found on starlings today.
Starting in the 1970s, a growing number of paleontologists argued that birds had evolved from a two-legged group of dinosaurs called theropods. The paleontologist pointed to traits in their skeletons found elsewhere only in birds. In 1996, Chinese paleontologists discovered the fossil of a theropod, Sinosauropteryx, that had whiskerlike structures on its head and back.
Since then, however, scientists have found a number of well-preserved theropod fossils with many more featherlike structures.
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