A UCLA team estimated Tyrannosaurus rex’s body temperature at about 97°F (36°C) by analyzing chemical signatures in three fossil teeth, according to a study published on September 16, 2026, in Science Advances. The authors said they could not completely rule out seasonal bias, although samples from different parts of two teeth produced statistically indistinguishable temperatures.
The estimate is above the 82–86°F range given for modern cold-blooded reptiles but below the 104–109°F range given for birds. The team said the findings suggest T. rex stayed warmer than its surroundings and may help explain how it could range across North America, including the Arctic.
