CHAPEL HILL - Working together on fossilized remains, Chinese and U.S. researchers have discovered a previously unknown species of primitive bird, a finding that offers new evidence that early bird evolution was considerably more complex than previously believed.
In the process, the scientists have identified on its nearly complete skeleton, the world's oldest surviving horny beak, part of a fossil dating back some 130 million years. They also say they've added more weight to the argument that birds descended not from dinosaurs, but rather from unknown earlier reptile ancestors.
"One of the really interesting things about these discoveries is that they unexpectedly and vividly show that birds had already diversified by the late Jurassic-early Cretaceous period," said Dr. Alan Feduccia, chair of biology at the University of North Carolina at Chapel Hill. "The oldest known bird, Archaeopteryx, which dates to 150 million years ago, had no beak, but rather a very reptilian jaw with teeth."
A report on the discovery appears in the June 17 issue of Nature, a British science journal. Besides Feduccia, authors are Drs. Lianhai Hou and Fucheng Zhang of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing and Larry D. Martin and Zhonghe Zhou of the University of Kansas in Lawrence.
The researchers have named the new species Confuciusornis dui in honor of Wenya Du, the man who collected the specimen near the edge of a lake in northeast China's Liaoning Province and donated it to the Beijing institute. It is a smaller but close relative of Confuciusornis sanctus, another crow-like bird of the same age the researchers found and reported in Nature in 1995.
Because hundreds of specimens of C. sanctus now have been found in the same area, volcanic eruptions likely killed them along the lakeshore instantaneously and froze them in time, Feduccia said. The new species was an unexpected but pleasant surprise.
"This bird was more advanced than Archaeopteryx in that it had a beak but was less advanced in that it had two small openings in the rear of its skull very similar to the reptile progenitors of birds," he said. "This is a mosaic pattern we see very much in vertebrate evolution - in other words, various lineages showing both primitive and advanced features at the same time. What this really shows is that early bird evolution was not linear, as many people have depicted it, but rather a far more complicated 'bush' with many extinct lines."
Neither of the two cousin species likely were ancestors of modern birds, Feduccia said. Instead, they were side "twigs" that disappeared from their family tree -- or bush -- millions of years ago.
Males of both species bore two long tail plumes indicating the sexes differed significantly from each other. Like its cousin, the new bird C. dui also grew asymmetric wing feathers characteristic of all modern flying birds. Ostriches and other birds that can't fly well sprout nearly symmetric feathers incapable of creating an airfoil and hence lift.
"These birds also have highly curved foot claws and reversed big toes showing they were clearly tree-dwelling creatures," the scientist said. "Together, these and other characteristics -- and the fact that the birds lived in complex social colonies - show that they were pretty well developed.
"It seems to us that this was a tree-dwelling bird, not an earth-bound, feathered dinosaur as people advocating a dinosaur origin of birds have said."
In 1979, Feduccia made international news by publishing a paper proving that the oldest known bird, Archaeopteryx, could fly because its wing feathers were asymmetric. Barbs on one side of its wing feather quills clearly grew longer than barbs on the other side.
"Some other scientists had speculated that Confusciusornis was a ground-living predator whose beak may have been hooked like a hawk, and this restoration was recently featured as a cover of Scientific American," Martin said. "The new fossil shows something very different. The beak is pointed and turned up at the tip very much like the cartoon bird Woody Woodpecker."
Combining modern and ancient features in the same skull was surprising, he said.
"This is very much like having the space shuttle with a back end built like a Model T."
Dui, the new specimen, also shows that the half-moon shaped bone in the wrist that's been used to support a dinosaurian ancestry for birds is the same in Confusciusornis and Archaeopteryx as in modern birds, but is a different bone in dinosaurs, Martin said.
"It no longer can be one of the main supports for a dinosaurian origin of birds," he said.
The above story is based on materials provided by University Of North Carolina At Chapel Hill. Note: Materials may be edited for content and length.
Cite This Page: