Artist's impression of the 110 million-year-old amphibious bird Gansus yumenensis, in a lake in what is now the Changma Basin of northwestern Gansu Province, China.
Credit: Mark A. Klingler/CMNH
SYDNEY, 16 June 2006 - The earliest known ancestors of modern birds may have been aquatic birds like ducks, according to new evidence uncovered in China.
Research published in today's issue of the U.S. journal Science, said new bird fossils preserved in almost pristine condition were found in an ancient lake near Changma, about 2,000 kilometres west of Beijing and have been dated to 110 million years ago.
The remains of the five Gansus yumenensis skeletons were found mostly unbroken and uncrushed with the added bonus of carbonised feathers and foot webbing. The lead author, Hai-lu You of the Chinese Academy of Geological Sciences, said that the fact the birds lived and died in a lake was the key to the quality of the fossils. "Extremely fine sediment can be deposited yearly and soft parts can be preserved," he said.
G. yumenensis belongs to the group Ornithurae, an ancient lineage of birds which includes all modern birds (Neornithes) and their immediate fossil ancestors. Palaeontologists believe ornithuran birds probably developed sometime between 140 and 110 million years ago in the Early Cretaceous period.
Ornithuran fossils "are relatively rare in the Cretaceous, which is part of what makes Gansus so exciting," said co-author Matthew Lamanna of Carnegie Museum of Natural History in the USA. The lake has yielded around 50 Gansus fossils, but none so complete as the latest find.
Other ornithuran birds have also showed aquatic adaptations. Said Lamanna: "When we mapped ecology onto our evolutionary tree, a pattern became apparent that species leading up to modern birds are mostly aquatic." Modern terrestrial bird groups like the ostrich family have ornithuran relatives dating back to the Cretaceous, suggesting to researchers that some early members of the modern bird group went back to living on the land.
The famous deposits of ‘feathered dinosaurs' at Liaoning Province (northeast of Beijing) are only a few million years older than the Changma fossils. Since this Liaoning group, the enantiornitheans, subsequently died out, comparison between the two groups may provide an understanding as to how and why ornithurans dominated over enantiornitheans.
Liaoning provided an insight into ecosystems around 125 million years ago so now Changma may provide insight into the events shortly after that. "It may represent not only the next chapter in bird evolution, but the next phase in the evolution of a lot of different types of organisms," said Lamanna.
