Four-winged bird sheds light on origins of flight

Posted by Emma Woollacott

A Chinese-American team says it's settled the long-standing question of how bird flight began.

The researchers conducted flight tests on a model of a four-winged gliding raptor called microraptor, and concluded that flight began as a process of gliding between trees.

While this might seem obvious, many paleontologists have argued strongly that animals developed flight as ground dwellers.

But the team from the University of Kansas and Northeastern University in China says that fossils of the hawk-sized microraptor backs up the gliding theory.

"We've done the scientific work and flight tests to show that microraptor was a very successful glider," said Burnham. "In 2003, they found one that was so well-preserved that you could count the feathers on its wings."

The new flight model is modeled on casts of the original bones of a microraptor and the preserved impressions of feathers from specimens in Chinese museums.

The fossils show, says the team, that an essentially sprawling posture gave a plausible hind-limb wing position to provide stable flight, with gliding parameters better than those of modern flying lemurs.

The 'biplane' posture advanced by some other researchers suggested that an upright stance was best for gliding. But the KU-China team argues that this would require an impossibly heavy head to maintain a proper center of gravity.

In any case, they say, the presence of seven-inch-long flight feathers on the feet would make any extended stay on the ground pretty tricky. Thus, microraptor must have been completely arboreal.

"We decided that we would take the skeleton we had, put wings on it from the feather pattern and show that it could fly," says KU's David Burnham.

"If others think that it was a terrestrial runner, they should make a model and put it on a treadmill and show that it could run with those long feathers on its hind legs."

So yah boo sucks to you.

A video of some of the flight tests is available here; details of the research appear in Proceedings of the National Academy of Sciences.