UCLA Study Finds T. Rex Body Temperature Similar to Humans

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UCLA scientists reported Wednesday they have determined the body temperature of Tyrannosaurus rex for the first time, using fossilized teeth to calculate that the dinosaur had a temperature of about 97 degrees Fahrenheit — roughly comparable to humans.

The findings, published in the journal Science Advances, provide further evidence that T. rex was warm-blooded and support theories that tyrannosaurs were active animals capable of surviving in climates too cold for many reptiles.

UCLA researchers developed a method about a decade ago to determine whether extinct animals were warm- or cold-blooded by measuring chemical bonds preserved in fossils. But testing the method on T. rex initially required more fossil material than museums were willing to provide.

Researchers subsequently refined the technique, reducing the amount of material needed by about 90%.

The Natural History Museum of Los Angeles County then provided portions of two teeth from Thomas the T. rex, the most complete of the tyrannosaur skeletons displayed in the museum’s dinosaur hall, officials said.

The researchers drilled enamel from the teeth and analyzed bonds formed by rare isotopes of carbon and oxygen. The number of those bonds varies with temperature, allowing scientists to estimate the temperature at which the tooth enamel formed.

The scientists compared the T. rex results with ancient crocodilian fossils from the same Hell Creek site in Montana. The crocodilian registered a body temperature of about 86 degrees, compared with 97 degrees for T. rex, helping researchers rule out the possibility that geological processes had altered the fossils to produce the temperature reading.

Researchers said T. rex’s ability to regulate its body temperature would have supported an active metabolism and allowed the animal to live across a broad range of climates.

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