Dinosaurs may have been warm-blooded: study

Dinosaurs may have been warm-blooded, scientists said Wednesday, in a finding that could debunk one of the most commonly-held images of the extinct giants.

Researchers in Spain and Norway reported in the journal Nature they had found tree-like growth rings on the bones of mammals, a feature that until now was thought to be limited to cold-blooded creatures ... and dinosaurs.

They also found evidence that dinosaurs probably had a high metabolic rate to allow fast growth ― another indicator of warm-bloodedness.

"Our results strongly suggest that dinosaurs were warm-blooded," lead author Meike Koehler of Spain's Institut Catala de Paleontologia told AFP.

If so, the findings should prompt a rethink about reptiles, she said.

Modern-day reptiles are cold-blooded, meaning they cannot control their body temperatures through their own metabolic system ― relying instead on external means such as basking in the sun.

While the dinosaurs may have been warm-blooded, their other characteristics kept them squarely in the reptile camp, said Koehler.

Palaeontologists have long noted the ring-like markings on the bones of cold-blooded creatures and dinosaurs, and taken them to indicate pauses in growth, perhaps due to cold periods or lack of food. (AFP)