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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, say the team, which includes a Carolina researcher.
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 Alan Feduccia, Heninger professor and chair of
biology at Carolina. "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."
A report on the findings appears in the June 23 issue of the journal Science.
Besides Feduccia, authors are 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.
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 Carolina 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; and
* 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."
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