Overview
- A peer‑reviewed study published Sept. 16, 2026 reports that clumped carbon‑oxygen isotopes in three Tyrannosaurus rex teeth record an average internal temperature of about 97°F (36°C) with an uncertainty of roughly ±4.5°F.
- Researchers used a minimally destructive clumped‑isotope method that cuts required enamel sample size by about 90 percent, which persuaded the Natural History Museum of Los Angeles County to supply tiny shavings from two teeth of the mounted specimen known as Thomas.
- The team ran geological controls on five contemporaneous crocodilian teeth from the same Montana formation and measured lower temperatures near 87.6°F, supporting a biological signal rather than chemical alteration of the fossils.
- A sustained 36°C body temperature implies higher metabolic rates for the sampled T. rex, which would raise daily food needs, allow longer active periods, and help explain fossil finds at high latitudes in Late Cretaceous North America.
- Authors stress the result applies to the tested individuals and note dinosaur thermoregulation likely varied across species, and they propose wider use of the refined technique to test other dinosaur groups and early mammal relatives.