Oct. 12, 2005 — Dinosaurs never had feathers, according to a new study that could through a wrench into the popular theory that birds directly evolved from carnivorous, two-legged dinosaurs.

While the authors of the new Journal of Morphology study believe that birds and dinosaurs likely had some reptilian ancestor in common, they think many scientists have jumped to incorrect conclusions about links between today's birds and prehistoric dinos.

Alan Feduccia, lead author of the paper, told Discovery News that the problem really began to surface in 1996, when an official from the National Geological Museum in Beijing presented a photo of what was said to be the first "feathered dinosaur," a small dino called Sinosauropteryx from the early Cretaceous, around 127 million years ago.

Sinosauropteryx had fossilized "fuzz" on some of its bones, which the Beijing researchers identified as protofeathers, or an early type of feather that may have evolved into full-fledged feathers in birds.

"The next day the New York Times ran a cover story and since then, other media have popularized the idea of feathered dinosaurs and their direct link to birds when, in reality, no biological or structural science supports the claims," said Feduccia, who is a professor of ornithology and evolutionary biology at the University of North Carolina at Chapel Hill.

Feduccia and his team analyzed the Chinese data and studied the structure and decomposition of collagen fibers in existing animals, such as snakes and lizards.

According to the new study, these fibers, once decomposed, resemble the "fuzz" on dinosaurs.

"The so-called protofeathers appear to us to be fossilized, flayed skin," he said.

He added that the Cretaceous dinosaurs from China existed around 25 million years after the earliest known bird, Archaeopteryx, which lived about 150 million years ago.

"Archaeopteryx had a bird brain, wings, and feathers that appear to be virtually identical to those of modern birds, so it is preposterous to suggest early Cretaceous dinosaurs originated feathers and were the direct ancestors of birds because feathered birds already existed," Feduccia said.

He and his colleagues believe Velociraptor and other very bird-like microraptors that had feathers and are categorized as dinosaurs actually were flightless birds.

Feduccia and his team also examined the way digits formed within the wings and limbs of dinosaurs and extinct and existing birds. Many scientists who support the theory that birds evolved from dinosaurs point to the fact that both share a three-digit system somewhat comparable to the human thumb, index finger and middle finger.

The new study found that birds have more of an index finger, middle finger and ring finger arrangement within their wings and on their feet. Since this "digit identity" is different from what two-legged dinosaurs had, the authors of the new paper say their findings cast additional doubt on the hypothesis that birds evolved from theropods.

Instead, Feduccia supports the theory that birds and dinosaurs shared a common ancestor, but that birds and dinos developed separately on their own evolutionary paths.

"A good candidate for this common ancestor is Lagosuchus, a small, quadrupedal archosaur (ancient reptile) that lived around 220 million years ago in what is now Argentina," he said.

He explained that Lagosuchus had a five-digit hand that could have evolved into the digits found on both birds and dinosaurs.

John Ruben, chair of the Zoology Department at Oregon State University, told Discovery News that the new study is "quite good and presents very carefully researched data."

Ruben said, "There is no question birds and dinosaurs are closely related, but the question is, do birds emerge after the appearance of meat-eating dinosaurs or beforehand."

Ruben, like Feduccia, believes the evidence as it stands now does not support the existence of feathered dinosaurs or the theory that birds evolved from carnivorous theropods.

Frances James, professor emerita in the Department of Biological Science at Florida State University, told Discovery News that she also supported the new study's findings.

"Flight must have evolved from the trees down and not from the ground up," she said. "The ancestor to birds therefore could have been some arboreal archosaur, but we just don't know. The question as to where birds came from is now left open."