A fossil unearthed in China may provide a first look at dinosaurs' bird-like sleep.

Xu Xing, of the Chinese Academy of Sciences, and Mark Norell, of the American Museum of Natural History, said in a report published in the American journal Nature that the fossil was discovered in Beipiao, Northeast China's Liaoning Province. It has lain undisturbed for around 140 million years.

The two scientists said the specimen was preserved in a stereotypical sleeping or resting posture strikingly similar to that of modern birds, showing that this position might have evolved before they did.

It is the first such fossil to be found in a sleeping pose.

It was named it Mei Long, "soundly sleeping dragon."

Mei Long seems to have died with its hind limbs folded underneath it and its head tucked under one forelimb, just as birds roost, with their head under their wing.

The fact that Mei Long seems to have a sleeping habit similar to that of modern birds could mean that the two share a common ancestor not much older than the dinosaur itself, the authors said.

It is rare for a fossil to be preserved in a "life pose," which can tell people about an animal's behaviour as well as its body.

Mei Long may have been buried alive quickly as a result of an eruption, the report says. It was found in volcanic sediments in Liaoning Province. There's lots of ash in the sediments.

It could also have been poisoned by a noxious gas such as carbon monoxide.

The specimen's bird-like-posture also could hint that the animal was warm-blooded. Modern birds tuck their heads under one wing to conserve heat.

This closeness is underlined by the dragon's diminutive size. At just 53 centimeters long, the discovery would support the theory that the evolution of flight in birds was helped by the fact that, as a family, they were fairly tiny.

The scientists speculated that Liaoning might be the world's richest treasure trove of fossil dinosaurs since numerous other three-dimensionally preserved vertebrate fossils have been recovered recently at this locality, including some specimens which shed light on behavioral information.

(China Daily October 16, 2004)