Paleontologists working in China say they have unearthed the first fossil of a dinosaur that appeared to have mature feathers identical to those of modern birds, including long, showy plumage on its tail and hind legs.
The U.S.-Chinese research team said the 3-foot fossil should settle once and for all the acrimonious debate over whether birds and dinosaurs are related.
It also reinforces the idea that dinosaurs were not cold-blooded after all, as the textbooks said for generations, but warm-blooded creatures that needed feathers for warmth, not flight.
The specimen is believed to be about 128 million years old. It is a small, fleet-footed theropod, a two-legged carnivore that could not fly and belongs to the same family as the larger and more fearsome Tyrannosaurus rex.
The researchers said the evidence of feathers consists of feathery impressions in the rock as well as what they described as "feather residue."
Details of the discovery will appear in Nature issued on March 7, 2002. The fossil is housed at the Beipiao Paleontological Museum in China.
"We have unequivocal feathers on an unequivocal non-avian dinosaur," said the study's lead author Mark Norell, paleontology chairman at the American Museum of Natural History in New York City.
The feathered theropod is the latest in a succession of fossils from China's Liaoning Province that have stirred the bird-dinosaur debate.
But it is unlikely to settle the question.
Skeptic: fossil was "salted"
Critics complained they are limited to examining photographs of the specimen. And they were skeptical that the specimen contains either tail feathers or feather parts, including the rachis, which is the central hollow supporting shaft of modern feathers.
Other feathers apparent in the specimen could have come from actual birds of the early Cretaceous Period that were mixed into the rock formation, researchers said. Or the specimen could be a composite from several sources, they suggested.
"I am not impressed," said Storrs Olson, senior zoologist at the Smithsonian Institution's National Museum of Natural History and an ardent critic of Norell's work. "I would want to be very certain that the fossil has not been deliberately salted with feathers from some other source."
The specimen is a dromaeosaur, a predator with hollow bones that were strikingly like a bird's. It was armed with a killing talon on each foot.
The quarry site once was a pond rimmed by forest. Volcanic eruptions filled the pond with talc-like ash and buried creatures. The dense layer contained little trapped oxygen, preserving rare details of the creatures, as well as petrifying their bone.
Norell said the specimen has a group of feathers at the end of the tail, giving it a much more extensive tail plume than previous specimens.
Feathers also fringe the back of the forelimbs and hindlimbs, as well as the front and back of the hand. Some measure more than 5 inches long.
(China Daily March 7, 2002)