Dinosaurs may be warm-blooded animals.

Through dinosaur fossils of tyrannosaurs and other species, scientists inferred their body mass index and growth rate to judge their metabolism, and found that these former dominants of the earth were warm-blooded animals just like modern mammals.

Other researchers concluded last year that dinosaurs were neither cold-blooded nor warm-blooded, and that their metabolism was somewhere in between. Michael D’Emic, a paleontologist at Stony Brook University in New York, disagreed.

Scientists began to argue in the 19th century whether dinosaurs were cold-blooded animals that were thought to be slow and bulky at first, or whether they had warm-blooded physiological functions and could have an energetic lifestyle.

Demick believes that last year’s study underestimated the growth rate of dinosaurs and should use statistical methods to analyze dinosaurs in the same group, as in the case of modern birds.

“The focus of my research so far is that dinosaurs, on average, are warm-blooded animals like modern mammals,” he said.

Last year’s study suggested that dinosaurs might raise their body temperature to a certain extent, enough to make their nerves and muscles work faster and turn them into fast predators, but not enough to regulate their body temperature at all times.

This adjustment allows them to sprint quickly, but usually they move slowly. Based on their analysis, the researchers reckon that if Tyrannosaurus Rex had what we know about warm blood metabolism, it would have to eat continuously in order to survive.

But Demick knows that his reasoning is far from enough to end the debate: “Overall, we know little about dinosaur growth, because we seldom study them in this way.” “My research argues that the dinosaurs I’ve observed have mammalian-like metabolic and growth rates, but of course that doesn’t mean that all dinosaurs are like this.”