T. rex teeth reveal the dinosaur's body temperature

Paleontologists analyzed clumped isotopes in three T. rex teeth from Montana's Hell Creek Formation, revealing a body temperature of 36.3 ± 2.5°C—matching modern mammals and birds. This warm-blooded physiology allowed T. rex to thrive across North America, even in cooler regions, and explains its dominance as a top predator requiring vast amounts of food.

The clumped isotope-derived T. rex body temperature of 36.3 ± 2.5°C is in agreement with those of extant large mammals such as Indian and African elephants with reported body temperatures of 36.0° and 36.2°C, respectively.