Science: Dinosaurs got feathers to stay warm

In the world of dinosaurs, one argument is increasingly occupying scientists: did birds evolve from lizard-like dinosaurs, or from some other group of animals?

Now, two newly discovered specimens from China seem to show dinosaurs which developed primitive feathers for warmth rather than flight, and could be early ancestors of today's birds.

The well-preserved fossil skeletons of the chicken-sized biped dinosaur Sinosauropteryx, which lived about 140 million years ago, were recently found in Liaoning in north-eastern China. The most interesting discovery was the quill-like "integumentary structures" covering both specimens, the science journal Nature reports today. Running from the base of the head along the back and tail, they are thought to be the remains of feathers, or feather-like structures, but were clearly not designed for flight. It is possible they were used to stop the dinosaur losing body heat, which would suggest they were warm- blooded, unlike lizards which are cold-blooded.

The argument over whether birds developed from dinosaurs has intensified in the past few years. The generally held view is that Archaeopteryx, a dinosaur with wing-like arms which lived about 150 million years ago, was the precursor of modern birds. But that view has been challenged by a group of scientists who think they evolved in parallel from a common ancestor with dinosaurs. The evidence from Sinosauropteryx indicates that feathers evolved from simpler, branched structures that appeared in non-flying dinosaurs, possibly as a means of insulation.