Scientists Took a Tyrannosaurus Rex’s Temperature for the First Time, and It was Almost Like that of a Human

Scientists took a Tyrannosaurus Rex’s temperature for the first time, finding it to be almost like that of a human. The study, published in Science Advances, used a technique that measures body temperatures of extinct species by analyzing isotopes in fossilized teeth. The researchers found that T. rex maintained a body temperature of around 97°F, comparable to humans. The method, which involves analyzing carbon and oxygen isotopes in tooth enamel, was refined over the years to require only 10% of the original fossil material. The study used two teeth from a T. rex skeleton on display at the Natural History Museum of Los Angeles County. The sample was taken from Montana’s Hell Creek site, a major source of preserved dinosaur material. The team compared their findings with a crocodilian sample from the same site to rule out local geology influencing the results.

• The study used a technique that measures body temperatures of extinct species by analyzing carbon and oxygen isotopes in fossilized teeth.
• The researchers found that T. rex maintained a body temperature of around 97°F, comparable to humans.
• The method was refined to require only 10% of the original fossil material.
• The sample was taken from Montana’s Hell Creek site, a major source of preserved dinosaur material.
• The team compared their findings with a crocodilian sample from the same site to rule out local geology influencing the results.

The findings offer direct evidence that T. rex could maintain an elevated body temperature even in challenging environments. The study suggests that T. rex was warm-blooded, a finding that contrasts with the typical cold-blooded nature of reptiles. The research also helps paleontologists understand the climate and lifestyle of T. rex. The study shows that T. rex could survive in colder climates, despite the generally warmer conditions of the Late Cretaceous. The work also helps reconstruct the range of North America 66 million years ago, based on where T. rex could have survived with a 97°F body temperature. The paper, “The Body Temperature of Tyrannosaurus Rex,” appeared in Science Advances on September 16, 2026.

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