The Discovery
For the first time, scientists have directly determined the body temperature of a Tyrannosaurus rex by analyzing fossilized teeth. The study, published in Science Advances, focused on minute fragments from two teeth of a T. rex skeleton named Thomas, housed at the Natural History Museum of Los Angeles County.
Lead author Ariadhna Tripati and her team spent over a decade perfecting their methodology. Their work enabled them to decrease the volume of fossil material required for analysis by 90 percent, opening new possibilities for studying delicate specimens.
What Scientists Found
The testing method examines oxygen and carbon isotopes trapped inside tooth enamel. Because the chemical bonds between these isotopes form according to temperature during enamel growth, researchers were able to decipher the thermal record preserved for 66 million years. The results showed that T. rex had a body temperature of roughly 97°F, which is very close to human body temperature.
The research team also incorporated paleoclimate models to examine the historical geographic range of the species. The findings suggest T. rex may have occupied a vast territory across North America, extending from present-day Mexico to Alaska.
Why It Matters
This high body temperature offers further confirmation that T. rex was warm-blooded. Having an elevated internal temperature would have enabled the predator to maintain an active metabolism, stay mobile far longer than cold-blooded animals, and live in cold climates. This supports earlier evidence of warm-bloodedness, including a fossilized footprint discovered in Alaska in 2022.
Moving forward, researchers aim to test this tooth enamel technique on various other dinosaur species to explore how thermal regulation functioned across prehistoric species and trace the evolution of warm-bloodedness.
Source: dinosaur fossil discovery - BingNews · Published September 27, 2026