Mesozoic World

A fossil dinosaur has been unearthed that was wrapped from head to tail in feathers.

It will add to the debate about birds being descended from dinosaurs and suggests that the evolution of feathers predates the development of flight.

The 130 million-year-old Dromaeosaur specimen provides the best evidence yet that some dinosaurs developed primitive feathers - not for flight but probably to keep warm. The creature was a small predator closely related to the Velociraptor which starred in the film Jurassic Park.

Like Velociraptor they had a sickle-like claw on the middle toe, sharp teeth, and a bone structure similar to that of modern birds.

Barbed features

The fossil was unearthed last spring by farmers digging in north-eastern China's Liaoning Province. It was entombed in two slabs of fine-grained rock.

When the slabs were separated they saw a fossil that resembles a large duck with a long tail and an oversized head. The fine-grained rock allowed minute details to be preserved showing that the creature's head and tail were covered with downy fibres, while other parts of the body seemed to have tufts or sprays of filaments resembling primitive feathers.

The arms also seemed to be adorned with branched structures similar to the barbs of modern bird feathers.

Fierce arguments

Dr Mark Norell, from the American Museum of Natural History, New York, said: "This fossil radically modifies our vision of these extinct animals. It shows us that advanced theropod (two-legged) dinosaurs may have looked more like weird birds than giant lizards."

Several new species of dinosaur with feather-like structures have been found in the Liaoning fossil beds since the first, Sinosauropteryx, was discovered in 1995. In most cases, the fossils were incomplete, making it unclear how the featherlike structures related to the animal's body. Most experts believe that modern birds evolved from dinosaurs, and cite the Liaoning fossils as evidence.

However, critics of the theory have argued that the feather-like structures are not the remains of primitive feathers, or that the specimens are mixed-up fossils of early birds and dinosaurs.

Body temperature

The new find may help resolve the debate. It contains details so fine that scientists will be able to see how the primitive feathers were attached to the dinosaur's body.

Ji Qiang, from the Chinese Academy of Geological Sciences, Beijing, said: "This is the specimen we've been waiting for. It makes it indisputable that a body covering similar to feathers was present in non-avian (flightless) dinosaurs."

The Dromaeosaur is more primitive than birds, suggesting that feathers developed before flight. Scientists think the feathers may have evolved as insulation to keep the animal warm. Dr Norell said: "It's conceivable that smaller dinosaurs like this one and even the young of larger species like Tyrannosaurus rex may have needed featherlike body coverings to maintain their body temperature."

The Dromaeosaur fossil, on loan from China, was being displayed for the first time at the American Museum of Natural History in 2001. While in the United States, it also travelled to Texas for imaging with a CAT scanner, which provided a three dimensional view of the skeleton.

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