New Claim on Bird Family Tree Ruffles Tempers
A rare fossil of a plumed reptile 75 million years older than the earliest known bird is challenging the popular idea that dinosaurs and modern fowl are birds of a feather.
The tiny primordial creature, which predates all but the most primitive dinosaurs, had feathers like a bird, according to new research made public today in Science. That has some questioning a widely held theory that birds are descended from the same dinosaur family that gave rise to tyrannosaurs, velociraptors and other toothy denizens of a vanished world.
Several scientists were elated by the find, saying it could topple a cherished scientific shibboleth about the origin of birds. Ornithologist Alan Feduccia at the University of North Carolina, a coauthor of the new study, called the theory that birds are related to dinosaurs “a delusional fantasy.”
Other experts, however, just as quickly dismissed the new finding as a flight of fancy. “This is quackery, basically,” said Richard O. Prum, a leading expert on ornithology and the origin of feathers at the University of Kansas, who has seen the fossil.
“I don’t believe those things are feathers,” said Luis M. Chiappe, an expert on avian evolution at the Los Angeles Museum of Natural History.
Indeed, among authorities on dinosaurs and birds, the responses from each faction have been as vociferous and predictable as a party-line split in a congressional budget debate.
Stirring these partisan passions is a fossil of a four-legged creature perhaps 10 inches long that skittered through the groves of central Asia 220 million years ago. At that time, the planet was dominated by a single massive continent and lumbering reptiles were the kings of creation.
Called Longisquama insignis, it was a member of the group of reptiles that gave rise to dinosaurs, crocodiles and birds.
The specimen appears to show half a dozen pairs of unusual feathery spines sprouting like wings from the animal’s back. Whether they were true feathers, vanes, spines, weird scales or folds in a flap of membrane is in the eye of the beholder.
Such fierce clashes of irreconcilable views may be disconcerting to a public that expects certainty from scientists, but the disputes are the essence of the highly competitive research process.
“One of the great things about science is that it is not like religion. . . . You always have to be willing to give up everything you believe, if the evidence is there,” said Mark A. Norell, an expert on dinosaurs and bird evolution at the American Museum of Natural History in New York. However, Norell has no doubt that the new study is wrongheaded.
As the scientists argue heatedly, the dead past has never seemed so lively.
The fossil was discovered in Kyrgyzstan in 1969, cursorily examined and then stored in a drawer at the Russian Academy of Sciences’ Paleontological Institute in Moscow for many years, unavailable for detailed analysis.
Not until the fossil came to Kansas last year as part of a touring exhibit of Russian fossils did U.S. scientists have a chance to scrutinize it.
Two paleobiologists from Oregon State University--John Rueben and Terry D. Jones--caught up with the exhibit at a shopping mall, took one look at the fossil and concluded that its importance had been overlooked.
It appeared to have feathers, they said.
“This animal looks like an ancestral bird, even if you ignore the feathers,” said Jones, who is now at Stephen F. Austin State University in Texas. “So we are quite sure we are looking at the earliest feather. That means there is very little chance that feathers could have originated in dinosaurs.”
The fossil also shows rows of elongated scales along the creature’s front legs, chin and neck resembling the fringe-like ruffles of skin that decorate a modern lizard called the bearded dragon, which is often sold in pet shops.
Several things convinced Jones and his colleagues that the structures along the animal’s back were feathers instead of scales.
They identified a long, thin “shaft” running down the center of each structure. A dense row of fine strands called “pinnae” project from either side, Jones said.
The base of the shaft is divided into several subsections, which is thought to be a signature of the complex developmental patterns unique to feathers. Other features also seem to be evidence of a development pattern resembling that of modern plumage, he said.
Other experts said the discovery that feathers might have evolved so early does not, by itself, disprove the relationship between birds and dinosaurs.
At the least, the new fossil find may be consistent with a growing storehouse of evidence that feathers--once thought to be unique to birds--may have been as common among dinosaurs and their predecessors as horns, spikes, elaborate frills and bony crests.
Recent fossil finds in China have turned up several examples of carnivorous dinosaurs covered with down or with tails tipped with plumed feathers, suggesting that modern feathers are a surviving trace of a relatively common feature of creatures that lived long before birds appeared or the beginning of bird-like flight.
Even so, several experts said, the fossil is not enough to disprove the close kinship between birds and dinosaurs, which is based on additional anatomical and behavioral evidence.
Chiappe at the Los Angeles Museum of Natural History said, “I don’t think that you can say that because they have feathers these animals are the ancestors to birds and forget everything else we know that supports the [theory that] birds evolved from dinosaurs.
“This is a very weird animal that we know very little about.”
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The Origin of Birds
A reptile with feathers that predated most dinosaurs would challenge the theory that modern birds are descended from dinosaurs.
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Sources: Science magazine; “From So Simple a Beginning,” Associated Press
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