Fierce, Yes, But Feathered, Too

Picture this: Adult Velociraptors, savage man-sized hunters with slashing claws, may have been covered in downy feathers, like newly hatched chicks. The same goes for the young of Tyrannosaurus rex, and even the full-grown monster might have had a tuft or two. A recent fossil find--a down-covered Velociraptor relative called a dromaeosaur--is fueling speculation that dinosaurs up and down the family tree may have sported plumage.

The 40-centimeter-high dromaeosaur, 125 million years old, is the latest of five stunningly well-preserved fossils unearthed over the last several years from fossil beds in China. All of the fossils are apparently clad in some kind of feathers, ranging from fibrous down to true feathers as unmistakable as a pigeon's.

Reported this week in Nature by Xiao-Chun Wu and his colleagues at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, the new fossil "has more bird features than any of the other feathered dinosaurs [do]," says James Clark of George Washington University. At the same time, the fossil makes it almost certain that the later, larger Velociraptors had similar plumage, notes dinosaur paleontologist Mark Norell of the American Museum of Natural History in New York. "We have as much evidence that Velociraptors had feathers as we do that Neandertals had hair," he says.

A small, energetic band of dissenters is not at all ready to accept the feathery dinosaur hypothesis. The halos of fibers found around several of the crucial specimens, including the latest one, are far more likely to be some kind of fossilized internal connective-tissue fibers left behind when the flesh decayed than anything related to feathers, according to John Ruben of Oregon State University in Corvallis. "We think these are just collagen," he says.

If Ruben and his fellow skeptics are wrong about the nature of these fibers, the images of many familiar dinosaurs should be softened with a coating of down. But don't start describing T. rex to your 4-year-old as a toothy version of Big Bird. "Whether an adult T. rex had full plumage--well, there's no direct evidence for it, and it might not be great to have a lot of insulation when you weighed 5 to 6 tons and lived in an environment like Louisiana," says Thomas Holtz of the University of Maryland, College Park. "I wouldn't be at all surprised if adult T. rex had lost its plumage, although it may have had feathers here and there."