[Islam-Online- Science, Ideas & Technology]

WASHINGTON (AFP) - The discovery of a four-chambered dinosaur heart suggests the legendary creatures were warm-blooded and had relatively high metabolisms more like human beings than lizards, according to a report in Science magazine.

"It's truly amazing that this animal seems to have had such a highly-evolved heart," says Dale Russell of the North Carolina State Museum of Natural Sciences, who co-authored the report. "The implications completely floored me," he says.

X-ray imaging of the heart of a Thescelosaurus, a pony-sized 66-million-year-old vegetarian dinosaur whose remains were found in South Dakota, showed two ventricles and what scientists believed were the remains of two aortas, the four heart-chambers typical of warm-blooded animals. "This means that low- and high-oxygen blood were separated," says Russell.

In contrast, two-chambered hearts in cold-blooded animals allow mixing of oxygen-rich and oxygen-poor blood. Without purely oxygen-rich blood flowing to their muscles and other tissues, cold-blooded creatures, like reptiles, must make do with a slower metabolism - and a more sluggish lifestyle.

The analysis of the Thescelosaurus heart offers the strongest evidence yet supporting the growing view that dinosaurs were forerunners not of reptiles but of modern-day birds, which are warm-blooded like mammals.

Found in 1993 by professional fossil hunter Michael Hammer and his son, in South Dakota's Hell Creek, the Thescelosaurus - a 3.9-meter (13-foot) long, parrot-beaked plant-eater who probably weighed some 360 kilograms (800 pounds) - was remarkably well preserved in silt and sand.

Oxygen-poor environments, like the sediment beneath a streambed, can sometimes fossilize even the soft tissues of an animal, though researchers do not understand exactly how, according to the report