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FossilsChallenge Bird Origin

AP Science Writer

WASHINGTON (AP) JUNE 22, 2000 —The fossil of a small lizard-like, flying reptile with a complex set of featherschallenges the theory that birds evolved from dinosaurs, a new study says.

Researchers say the featheredreptile lived 225 million years ago, proving that feathered animals evolvedmillions of years before the appearance of the dinosaurs that most experts sayare the ancestors of modern birds.

The fossil has been calledLongisquama and is thought to be an archosaur, a member of a reptile group thatlater gave rise to dinosaurs, crocodiles and birds. The first known bird,Archeopteryx, appeared about 145 million years ago, some 75 million after thedate for Longisquama.

"Here you've got an animalthat isn't a bird and it isn't a dinosaur, and yet it has feathers,'' saidNicholas R. Geist, paleobiologist at Sonoma State University and co-author of astudy appearing Friday in the journal Science.

"It is going to be a majormonkey wrench in the theory about the dinosaurean origin of birds,'' he said."It is going to cause some people to take a real good second look at theirdata.''

However, Jacques Gauthier of YaleUniversity, an expert on the evolution of dinosaurs, said that Longisquama is apoorly preserved specimen that is important only "if you allow yourimagination to run wild.''

"Thereis a huge body of data that show birds evolved from dinosaurs,'' said Gauthier."This (the Longisquama study) is way over the top.''

Gauthier said that a singlespecimen is not enough to dismiss a theory that is supported by many studiesthat point to the dinosaur ancestry of birds, including evidence that somedinosaurs had feathers.

The Longisquama fossil includesthe head, forelegs and part of a torso of a lizard-like animal. Along its backare a series of appendages that Geist and his co-authors say are feathers.

Longisquama was found inKyrgyzstan, in central Asia, in 1969, and was stored for years in a drawer inMoscow. The specimen provoked little interest until it was included as part of atraveling exhibition and spotted at a shopping mall in Kansas by Oregon StateUniversity paleontologists John Ruben and Terry Jones, co-authors of the studyin Science.

Ruben and Jones said theyidentified the appendages on the back of the small fossil as feathers and begana long study of the small critter.

Jones said that the feathers alongthe back of Longisquama are fully developed and very "birdlike.''

"Theskeleton is also very birdlike,'' said Jones. "It has a birdlike head,shoulders and a wishbone. The wishbone is almost exactly like that ofArcheopteryx.''

Geist said the feather structureof Longisquama was well preserved in hardened mud because the animal apparentlysank to a lake bottom after it died.

He that Longisquama probably hadmuscle control of the feathers and that it used them to glide from trees. Theanimal was not able to achieve true flight as do modern birds, said Geist.

"Thesefeathers emerge from a follicle the way feathers do in modern birds,'' saidGeist. "They had a quill-like structure that was hollow.''

Geist said that feathers are verycomplicated structures and that it is unlikely that feathers would have evolvedtwice -- once among the early reptiles and then later among the dinosaurs.

Ruben said that other researchershave identified dinosaurs as having feathers and as being birdlike. But he saidtwo of the most birdlike dinosaurs, Bambiraptor and Velociraptor, lived 70million years after the earliest known bird.

Longisquama, however, he said,lived at the right time and had the feathers that suggest it could have been anevolutionary ancestor of birds.

Jones said that the feathers onLongisquama are so well developed that it is likely that the first feathersappeared on reptiles many generations before Longisquama came along.

But Gauthier said the study isgoing to have little effect on the theory that birds evolved from dinosaurs, anidea that can be traced back through the work of hundreds of scientists overmany decades.

Accepting a Longisquama as thefirst bird "would be like saying suddenly that humans are not primates oreven mammals,'' said Gaiter. He said more evidence than Longisquama would beneeded to disprove a theory that has been long accepted by the majority ofpaleobiologists.


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