Flying study

did the earliest flying birds evolve from fast runners that learnt to flap their wings and take off? Proponents of this theory have faced some nagging problems. How could a ground-dwelling animal run fast enough to reach takeoff speed, and why would it be flapping its wings?

One calculation based on the bone structure of Archaeoptery , the earliest bird suggested that it could reach a top running speed of only two metres per second, far short of the six metre per second needed for it to become airborne. But the calculation left out an important factor, says Phillip Burgers, of the San Diego Natural History Museum.

He points out that flapping wings provided forward thrust as well as upward lift. After calculations, the team found that Archaeoptery 's wings would have given enough forward thrust to accelerate the animal to takeoff velocity in just three seconds. Extra speed from flapping wings would have come in handy for earlier ancestors of birds whose wings were too poorly developed for flight, say experts. Researchers say this could explain why large feathered wings evolved in the first place.