When scientist Rich-ard Prum looked upon the dinosaur's remains, he could barely believe what lay before him. Locked in a slab of mottled brown stone was the fossil of a creature that, even in the fantastic world of the Cretaceous, seemed to spring more from imagination than from any era of Earth's history.
Very clearly, he saw the slender claws of a raptor, the wishbone-like pelvis - and four feathered wings.
It was a moment of revelation. For a decade, scientists burrowing through the farmland of northeast China had uncovered flightless, feathered raptors with two wings. The findings had, in no small part, confirmed the widely accepted notion that birds are descendants of dinosaurs.
But this discovery, announced yesterday, was something more. This peculiar creature, it seems, could fly, and etched in the fiber of its feathers and the spread of its wings were clues into one of the most tantalizing mysteries of paleontology: What did the first bird look like, and how did it first take flight?
They are questions that have filled letters and lecture halls since the days of Charles Darwin, when a curious bird-dinosaur was found in the limestone of a Bavarian quarry. Today, the discovery of what is likely that bird's cousin is again forcing scientists to challenge widely held theories.
"It is a remarkable find," says Paul Sereno, a paleontologist at the University of Chicago. "What this team has put together is amazing."
Specifically, Xing Xu and his colleagues at the Chinese Academy of Sciences have put together six specimens of an animal beyond most paleontologists' dreams. And their controversial report in this week's issue of Nature attempts nothing less than the overthrow of core scientific beliefs about avian evolution.