A new theory of how dinosaurs learned to fly has
According to a US scientist, flight may have
evolved in two-legged dinosaurs that flapped their feathered
fore-limbs to climb slopes.
They eventually developed true wings and became
flying birds, says Kenneth Dial of the University of Montana.
The idea is based on a study of the habits of
modern flightless birds, which beat their wings to scurry up hills
and get away from predators.
It turns out that the physics of this
sort of flapping motion is different from that of aerial flight.
Professor Dial says it helps push the birds' feet
against the slope, thus improving traction - in the same way that
spoilers work on a racing car.
He came to this conclusion by studying partridges
running up hills and measuring their speed.
Even chicks with downy fluff were better at getting
up steep slopes than those whose flight feathers had been trimmed or
By modifying these wing movements, birds or their
ancestors - the dinosaurs - may have been able to launch themselves
into the air.
Fossils show that some dinosaurs had feathered
fore-limbs but were unable to fly - something that has puzzled
"The big dilemma has been, 'How do you explain the
partial wing?'," says Professor Dial.