T. Rex Tooth Isotopes Show Heat of an Elephant

Fossilized Tyrannosaurus rex teeth are yielding a new kind of vital sign. By measuring isotope ratios preserved in the teeth, researchers have found evidence that the dinosaur ran at a body temperature similar to that of a modern elephant. The technique offers a fresh way to probe the biology of extinct animals.

The results suggest that T. rex was not merely absorbing heat from its surroundings but was actively managing its internal temperature, according to the report. Elephants are a relevant comparison because they are large animals that maintain a stable, high core temperature despite their size.

The authors frame the evidence as a hint rather than a definitive measurement. The finding adds to a long-running debate about dinosaur metabolism, and if it holds, it could inform how paleontologists understand the activity and energy demands of the Late Cretaceous predator.