The two new pterosaurs, however, have not been found there before.
Pterosaurs vs. Birds
The fossil deposits could provide researchers with an insight into the competition between pterosaurs and early bird species in this area of China.
"These areas of exceptional preservation give us a larger sample size that allows us to ask questions about community structure," said Jeffrey Wilson, a paleontologist at the University of Michigan in Ann Arbor. "For instance, which flying animalsbirds or pterosaurswere more predominant in this terrestrial deposit?"
Kellner suggests that birds must have been largely confined to inland areas, whereas pterosaurs dominated the coasts.
"Most pterosaurs come from deposits that represent ancient coastlines, lagoons, and shallow interior seas," Kellner said. "There birds were very rare. On the other hand the Liaoning deposits, which are far from the coast, show more birds than pterosaurs in both number of species and diversity."
But Wilson, the University of Michigan paleontologist, says it's too soon to make generalizations without comparing the recent finds with those in other deposits.
"We must ask whether this is a local or more general effect," he said. "After all there are few deposits to compare to the Jehol."
Other experts point out that pterosaurs were also quite common, although not diverse, in inland China at this time.
"The Tugulu group in northwestern China is roughly the same age as the formation in Liaoning, and pterodactyls [a kind of pterosaur] are incredibly common in it," said James Clark, a paleontologist at George Washington University in Washington, D.C.
Kellner acknowledges that there are many questions left unanswered about the pterosaurs.
"How do we know if Liaoning was a better place for pterosaurs to live than other places?" he said. "Actually we don't."
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