According to paleontologist Sankar Chatterjee and retired aeronautical engineer R.J. Templin, a small early Chinese dinosaur called Microraptor gui used a two-level, biplane wing configuration to fly from tree to tree in the early Cretaceous. Among the evidence for the early biplane is that Microraptor had unmistakable flight feathers on its hind limbs as well as on its wings, says Chatterjee, a distinguished professor at Texas Tech University in Lubbock. The Chinese paleontologists who first reconstructed Microraptor had guessed that its four wings were used in tandem, similar to those of dragonfly.
Chatterjee presented the new biplane flight findings on Sunday, 16 October, at the Annual Meeting of the Geological Society of America in Salt Lake City.
"The most unusual thing is that they have flight feathers not only on the hand section, but also on foot," said Chatterjee. Flight feathers differ noticeably from other feathers in that they are asymmetrical with interlocking barbules to keep their shape. The leading edge of each long feather was narrower than the trailing edge, which helped streamline the body in flight. The hooked, interlocking barbs gave strength and flexibility to the feather and prevented air from passing through it in flight.
Some present-day birds, especially raptors as well as the earliest Jurassic bird Archaeopteryx, also have (or had) feathers on their legs, Chatterjee says. But these are not flight feathers and appear adapted to streamline the legs during catching and carrying prey so they don't interfere with flight.
Another key element to discovering Microraptor's flight secrets was setting some realistic limitations on how the dinosaur could move its hindlimbs ? something that was initially overlooked by Chinese
Source:Geological Society of America