The long-standing belief that dinosaurs were cold-blooded may have been premature, if new research into herbivorous mammals is anything to go by, potentially overturning dino theory. Dinosaurs had long been assumed cold-blooded because bone microstructures identified in fossilized remains showed portions of slowed development also seen in lizards and crocodiles today. However, Nature reports, a new study has discovered that same pattern in warm-blooded animals.
The so-called lines of arrested growth (LAGs) had previously only been spotted in cold-blooded reptiles, usually connected to periods when resources are in short supply. A team led by palaeontologist Meike Köhler at the Autonomous University of Barcelona in Bellaterra, Spain, however, found the same LAGs in ruminants across the globe.
The study, published in Nature this week, suggests that slowing down body development is a method of energy conservation shared by warm- and cold-blooded animals, implemented when conditions become harsh.
“LAGs cannot be used as an argument that dinosaurs could not have been endothermic”, Köhler says of the study’s finding. In actual fact, dinosaurs are more likely to have grown rapidly and demonstrate high metabolic rates, the study concludes, with their bone tissue indistinguishable from that endothermic ruminants today.