"These studies have linked anatomical, physiological or behavioral inferences with an increased metabolic potential, suggesting that if not bird-like in metabolism, theropods were at least 'more similar' to birds than to reptiles," said the researchers.
A pulmonary machinery for enhanced gas exchange in dinosaurs would have produced a quick metabolism — necessary for a predatory lifestyle — pushing dinosaurs closer to being warm-blooded creatures.
"This doesn't mean they maintained this warm-bloodedness all the time. They probably fell somewhere between cold- and warm-blooded," O' Connor said.
According to Paul Barrett, a palaeontologist at the Natural History Museum in London, the research adds to evidence that counters theories which dispute a link between dinosaurs and birds.
"This work is another nail in the coffin for that competing theory," Barrett told
Nature.
