T. rex Teeth Indicate Body Temperature Close to an Elephant's, Researchers Say

The finding comes after a century of shifting views about the dinosaur. For most of the last century, T. rex was pictured as a sluggish, tail-dragging reptile that had to warm up in the sun before it could go anywhere. Further research changed that image and replaced it with the active, bird-like animal shown in the movie Jurassic Park. Whether T. rex used warm blood to power that activity remained a question. The new dental measurement may have brought scientists closer to an answer, according to the report.

The method used in the work is known as dental thermometry. The report says the team measured the T. rex body temperature by analyzing its teeth, yielding the roughly 36 degrees Celsius reading. That temperature is close to that of a modern elephant. The reading places T. rex near a modern elephant in body temperature, but the report does not present the broader debate over dinosaur thermal strategies as settled.

Paleontologists have long argued about dinosaur physiology using indirect evidence such as bone microstructure, growth rates, and where fossils turn up on the map. Some studies suggested many dinosaurs were endotherms, generating their own body heat like birds and mammals. Others argued that each lineage may have had its own thermal strategy. The new T. rex dental reading adds one more piece of evidence to that debate, pointing to a body temperature comparable to that of a modern elephant rather than to that of a sluggish, sun-warmed reptile.