Was the Archaeopteryx: Bird or dinosaur?
HOW DID birds learn to fly? For over a decade now, this question has been at the centre of a debate about whether Archaeopteryx, the world's oldest bird-like creature -- found nearly 150 million years ago -- was a bird or a dinosaur.
While ornithologists believe Archaeopteryx was a bird that perched on trees and tried to master the air, quite like the quixotic winged leaps made from towers by human beings, palaeontologists claim it was a feathered, ground-dwelling dinosaur whose descendents eventually took to the air.
But now, ornithologist Alan Feduccia of the University of North Carolina at Chapel Hill points to the claws of the Archaeopteryx to cement his argument that it descended from the trees and was undoubtedly a bird. (Science, Vol 259, No 5096). "Paleontologists have tried to turn Archaeopteryx into an earth-bound, feathered dinosaur," says Feduccia. "But it's not. It is a bird, a perching bird.
Feduccia found the rounded claws of three Archaeopteryx specimens matched those of perchers such as the South American motmots. Another piece of evidence came from the curved claw on the beast's first toe, which Feduccia says is "strictly a perching adaptation; it would be a tremendous obstacle to running on the ground".
The Archaeopteryx also possessed wing claws, which, according to Feduccia, was an adaptation for life on trees. "These claws are extremely similar to the foot claws of modern trunk-climbing birds," he insists, and adds, "In fact, you would be hard-pressed to differentiate between a Archaeopteryx's wing claws and those of a woodcreeper."
However, evolutionary biologist Paul Sereno of the University of Chicago questions whether the Archaeopteryx's claws could tell anything definite about its overall behaviour. Sereno says, "Many so-called ground birds, such as hens, still spend some time in the trees."