Paleontologists have argued over the years about whether dinosaurs were cold-blooded or warm-blooded. Due to varying evidence, multiple theories have emerged.
A Tyrannosaurus Rex could never have been warm-blooded because a cold-blooded animal needs less food than a warm-blooded animal. As big meat eaters, they would have to be hunting nonstop if they were warm-blooded. But if they were cold-blooded, they would have been able to take breaks, since cold-blooded animals need ten times less food. Some paleontologists’ theories say that some of the biggest dinosaurs, like the Diplodocus, were big enough that they were gigantothermic. This means that they held onto their warmth instead of cooling down when it got colder. So, they could have been warm-blooded without having a warm-blooded metabolism. Metabolism is the energy that an animal makes from its food. Studying animals metabolisms are just one of the many ways that scientists can tell if an animal is warm or cold-blooded. Investigating animals’ heart chambers is another way.
Warm-blooded animals have four-chambered hearts, and cold-blooded animals only have three-chambered hearts. Since no one has ever found an intact dinosaur heart, it hasn’t been possible to use this approach to find if they are warm or cold-blooded.
Paleontologists have also compared the ratio of predators to prey to find out whether animals are warm or cold-blooded. Since during the Mesozoic era, there were fewer predators than prey, this might offer proof that there were some warm-blooded dinosaurs.
Whether or not they were warm or cold-blooded or both, there is probably still a lot we don’t know about the lives of dinosaurs.