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For Immediate Release
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June 16, 2006
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preserved fossils from China providing new
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Pittsburgh … The discovery of dozens of beautifully-preserved fossils of the ancient bird Gansus yumenensis in China is providing fresh evidence of how and when modern-style birds evolved from their dinosaur ancestors.
A Chinese-American research team, co-led by Carnegie Museum of Natural History Associate Curator of Vertebrate Paleontology Matt Lamanna, PhD, Dr. Hai-lu You of the Chinese Academy of Geological Sciences, and Dr. Jerry Harris of Dixie State College of Utah, has unearthed approximately 40 new specimens of Gansus from Early Cretaceous (~110 million years old) lake beds near the tiny, remote town of Changma in northwestern Gansu Province. Several of these specimens are nearly complete skeletons; some preserve rarely fossilized soft-tissues like feathers and skin. The team's findings are published in today's issue of the journal Science.
The new specimens reveal that Gansus is the oldest known member of the Ornithurae, the group that includes all modern birds and their closest extinct relatives. Previously, members of the Ornithurae were known exclusively from beds that are Late Cretaceous (~99 million years old) or younger in age. Therefore, for its age, Gansus is the most evolutionarily advanced bird ever discovered. Additionally, many hind limb features of Gansus, most notably its webbed feet, demonstrate that it was semi-aquatic, adept at swimming and diving. As a result, the team has concluded that the modern-type birds may have originated in aquatic environments.
"Gansus is a missing link in bird evolution," said Lamanna. "It provides a rare and detailed picture of what the ancestors of today's birds were probably like, in appearance as well as habits."
Until the new Gansus fossils were discovered, all that was known of this bird was an incomplete hind limb found by Chinese paleontologists at Changma in 1981. Fossils of close relatives of living birds are generally rare in rocks from the Mesozoic Era (the "Age of Dinosaurs"), being greatly outnumbered by relatively primitive species that more closely resemble their dinosaurian forerunners. Because of this situation, how, when, and in what kinds of environments modern-style birds originated have remained unknown.
"The incompleteness of the original fossil of Gansus yumenensis prevented scientists from understanding much about this species and its relationships to other birds, so it was often ignored or forgotten," said Lamanna. "Our new specimens are extremely well preserved, with some even including feathers and webbed skin between the toes. Because these fossils are in such good condition, they've enabled us to reconstruct the appearance and relationships of Gansus with a high degree of precision. They provide new and important insight into the evolutionary transformation of carnivorous dinosaurs into the birds we know today."
In life, Gansus would have resembled a modern loon or diving duck, but it is not closely related to any particular bird group alive today. The new Gansus fossils were discovered during an expedition to Changma in the summer of 2004. This expedition was conceived in September of 2002, when Dr. You briefly visited Changma and recovered a fossil bird wing - after the original specimen of Gansus, only the second avian fossil ever found at the site. After showing them photos of this wing, Dr. You invited Drs. Lamanna and Harris, his former graduate school classmates at the University of Pennsylvania, to join him in exploring for additional bird fossils at Changma.
"We went to Changma hoping that we'd discover one, maybe two, fragments of fossil birds," said Lamanna. "Instead, we found dozens, including some almost complete skeletons with soft tissues. We were successful beyond our wildest dreams."
The fossil-bearing rocks at Changma formed in an ancient lake and today belong to a geologic unit called the Xiagou Formation. The Xiagou Formation appears to be approximately 5-15 million years younger than the fossil beds in northeastern China's Liaoning Province that are celebrated for their feathered dinosaurs and diversity of primitive birds. The localities at Liaoning are approximately 1,200 miles east of the Changma site; thus, Gansus is far removed both in time and space from its counterparts at Liaoning. As most of the bird fossils found at Changma are those of Gansus, the site also represents the oldest known locality where close relatives of modern birds outnumber the more primitive, dinosaur-like birds that predominated elsewhere at roughly the same time.
Apart from birds, the Changma site has already yielded fossils of many other types of Early Cretaceous organisms, including plants, aquatic invertebrates, insects, fish, a salamander, and turtles. Drs. Lamanna, You, Harris, and their team are optimistic that the scientific significance of the Changma site will eventually come to rival that of Liaoning.
"The fossil beds at Changma are probably younger than those at Liaoning by at least a few million years," Lamanna said. "Therefore, continued research at Changma should provide significant new information on ecosystems developing in Asia around 110 million years ago. We think there's a great chance that future expeditions to Changma will produce spectacular new fossils of many important kinds of plants and animals, such as flowering plants, feathered dinosaurs, and mammals. Such fossils will undoubtedly provide new insight into the evolution of these key groups.
"Thanks to the Liaoning sites, paleontologists now have a pretty good idea of what land ecosystems were like around 120-125 million years ago, when birds first really diversified. My colleagues and I want to know what happened next, and Changma is the perfect place to find out."
The expedition to Changma that unearthed the Gansus fossils was chronicled by The Science Channel in the documentary Rise of the Feathered Dragon, which premiered in February. The Science Channel will re-broadcast this program on Monday, June 19 at 9:00 PM EST.
In addition to Drs. Lamanna, You, and Harris, other co-authors of the Science paper on Gansus include Dr. Luis Chiappe and Jingmai O'Connor of the Natural History Museum of Los Angeles County; Drs. Shu-an Ji, Jun-chang Lü, Chong-xi Yuan, and Qiang Ji of the Chinese Academy of Geological Sciences; Da-qing Li of the Third Geology and Mineral Resources Exploration Academy of Gansu Province; Xing Zhang of the Provincial Museum of Gansu Province; Dr. Kenneth Lacovara of Drexel University; and Dr. Peter Dodson of the University of Pennsylvania.
Funding for the Changma research was provided by the Discovery Quest program for The Science Channel, Carnegie Museum of Natural History, Dixie State College of Utah, the Chinese Geological Survey of the Ministry of Land and Resources of China, and the Ministry of Science and Technology of China (973 project).
Please note: Matt Lamanna will be in Washington, D.C. during the week of June 12 but can be reached via e-mail, or by phone at (202) 633-1381 or (202) 737-2200. If assistance is required please contact:
a copy of the paper, please contact:
For comment on fossil birds and avian evolution:
Luis M. Chiappe
PLEASE NOTE: Dr. Chiappe is a co-author of the paper