US tooth study indicates Tyrannosaurus rex was warm-blooded
In the United States, scientists estimated the body temperature of Tyrannosaurus rex at approximately 36.3°C — close to the average human body temperature. An analysis of the chemical composition of the enamel of three T. rex teeth found in Montana indicates that this large predatory dinosaur was warm-blooded, Channel NewsAsia reports, citing Reuters.
Tooth enamel data
Researchers estimated T. rex's body temperature at 97.3°F, or 36.3°C, with a margin of error of 2.5°C. By comparison, the average human body temperature is 37°C. The figure is also close to the temperature of elephants — approximately 36°C — but lower than the average temperature of ostriches, which reaches about 39°C.
Scientists used a method of analyzing so-called clumped carbon and oxygen isotopes in tooth enamel. Enamel forms at an animal's body temperature, so its chemical composition can serve as a kind of thermometer. About 5 milligrams of enamel powder were taken from each tooth using a low-speed drill.
Comparison with crocodilians
Two teeth belonged to a well-preserved young adult tyrannosaur nicknamed Thomas, while another was part of a tooth from a different individual. All samples came from Carter County, Montana. They were provided by the Natural History Museum of Los Angeles County.
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For comparison, the scientists also studied five crocodilian teeth of the same age from the same geological formation. Their average temperature was estimated at 30.9°C, consistent with modern crocodilians and lower than the result for T. rex.
Senior study author, University of California, Los Angeles geoscientist Aradhna Tripati, noted that a warm-blooded animal does not depend on solar heat to maintain its body temperature. Study co-author Robert Eagle explained that a higher metabolic rate would have meant a greater need for food for T. rex, but would also have allowed it to remain active longer, hunt, migrate and live in colder conditions.
The study was published in the journal Science Advances. Scientists cautioned that conclusions about one species should not automatically be extended to all dinosaurs, as they may have had different thermoregulation strategies.
