CHAPEL HILL, June 22, 2000 -- By painstakingly studying a fossil unearthed in central Asia and first reported in 1970 by a Russian scientist named A.G. Sharov, a team of U.S. and Russian researchers has discovered what they believe are by far the oldest feathers ever found. Some 220 million years ago, the small primitive reptile could at least glide efficiently, the scientists say.
The discovery casts serious doubt on the view that birds descended from dinosaurs, as many paleontologists maintain. Ornithologists -- scientists who study birds -- say that could not have happened because feathers and the creatures that grew them predated dinosaurs. Instead, the latter believe both birds and dinosaurs undoubtedly evolved from earlier reptilian ancestors known as archosaurs.
"This question has been debated since the late 1800s and debated heatedly for about the past 10 years," said Dr. Alan Feduccia, Heninger professor and chair of biology at the University of North Carolina at Chapel Hill. "But just as you can't be your own grandmother, birds can't have come from theropod dinosaurs because the fossil record shows the time line is all wrong."
Feduccia first briefly examined the fossil of Longisquama insignis, an unusual archosaur from the Late Triassic period with wing-like appendages growing out of its back, in Moscow in 1982. At that time, he was given access to only part of the fossil and did not have special equipment the team used in its recent investigation.
"But the fossil was brought to Kansas City last year as part of a traveling Russian fossil exhibit, and Terry and John were struck by previously unnoticed similarities between the appendages and feathers," the UNC-CH biologist said. "We then got together as a team at the University of Kansas to study it in tremendous detail using microscopy."
The team found that the creature: . bore hollow-shafted feathers almost identical to modern bird feathers, . used the feathers, which evolved from reptilian scales, for flight instead of for regulating body heat, . molted like modern birds do, likely used aerodynamic forelimbs for steering and had a wishbone similar to modern birds.
"These are the earliest structures in the fossil record that can be called feathers," Feduccia said. "They predate the so-called 'fuzzy dinosaurs' from China by at least 100 million years. Here we show unequivocally that the earliest known feathers evolved in the context of flight and not thermo-regulation."
The exact relationship of Longisquama to birds is uncertain, he said, and they clearly were not birds themselves and probably did not evolve into birds. The oldest known bird, Archaeopteryx, dates back 150 million years.
In 1979, Feduccia made international news by publishing a paper in Science proving that the animal could fly because its wing feathers were asymmetric. Barbs on one side of its wing feather quills grew significantly longer than barbs on the other side, which is characteristic of modern flying birds, he observed. Barbs on either side of the quills of flightless birds are nearly symmetrical.
"The most bird-like of the dinosaurs, such as Bambiraptor and Velociraptor, lived 70 million years after the earliest bird," Rubin said. "So you have birds flying before the evolution of the first bird-like dinosaurs. We now question very strongly whether there were any feathered dinosaurs at all. What have been called feathered dinosaurs were probably flightless birds."
A report on the findings appears in the June 23 issue of the journal Science.
Besides Feduccia, authors are Drs. Terry D. Jones and John A. Ruben of Oregon State University, Larry D. Martin of the University of Kansas, Evgeny N. Kurochkin and Vladimir Alifanov of the Russian Academy of Sciences' Paleontologic Institute, Paul F.A. Maderson of the City University of New York, Willem J. Hillenius of the College of Charleston and Nicholas R. Geist of Sonoma State University. Jones, a student of Ruben's, is about to join the Stephen F. Austin State University faculty.
By DAVID WILLIAMSON UNC-CH News Services
Note: For fossil images, visit http://osu.orst.edu/dept/ncs/photos or call David Stauth at 541-737-0787. Feduccia can be reached at 919-962-8321 or 962-3050, Martin at 785-864-5639 and Ruben and Jones at 541-737-5347.
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Science