Dinosaurs were neither cold-blooded nor warm-blooded, study says

BY Justin Scuiletti  June 16, 2014 at 11:59 AM EST

A Tyrannosaurus rex skeleton on display at the Houston Museum of Natural Science. New research sheds light on dinosaur metabolism. Photo by Flickr user Erin Blatzer

A Tyrannosaurus rex skeleton on display at the Houston Museum of Natural Science. New research sheds light on dinosaur metabolism. Photo by Flickr user Erin Blatzer


Just like the bowl of porridge in “Goldilocks and the Three Bears,” it appears that dinosaurs’ body temperatures may have been just right.

New research published Friday by the University of New Mexico postulates that dinosaurs were not cold-blooded creatures as previously believed, yet not warm-blooded like mammals either. Instead, the study claims that dinosaurs were mesothermic — an intermediate stage between the two.

UNM graduate student John Grady, who led the research, compiled a database of animal growth versus energy use for the study, which found that animals that grew faster required more energy and possessed higher body temperatures. Applied to growth estimates for dinosaurs, their metabolic rates were calculated to lie in a middle ground between animals that are cold-blooded, which require the sun to regulate body temperature, and warm-blooded, in which the body can self-regulate.

Being mesothermic also explains why dinosaurs likely grew to be so large: such a metabolism would not require an animal of that size to constantly consume large amounts of food to regulate body temperature, also allowing the animal to move quickly without draining energy too quickly.