Tyrannosaurus rex maintained an average body temperature of about 36.3 degrees, functioning as an active, warm-blooded animal with a rapid metabolism, according to a study published in Science Advances. Researchers from the University of California, Los Angeles, alongside international colleagues, determined the prehistoric reptile’s internal warmth by analyzing rare chemical bonds preserved within fossilized dental enamel.
Dental Isotopes Reveal Endothermic Metabolism
To establish the dinosaur’s thermal regulation, the research team examined isotopic bonds formed by rare carbon and oxygen isotopes inside tooth enamel. According to UCLA researcher Robert Eagle, the concentration of these specific chemical bonds increases at lower temperatures and decreases at higher temperatures. Because tooth enamel consists of exceptionally durable crystalline structures, it preserves these temperature-dependent atomic arrangements across millions of years.
The analysis yielded a calculated body temperature of 36.3 degrees, give or take 2.5 degrees. This thermal baseline aligns closely with the body temperatures of mammals and humans, offering concrete physiological evidence that at least some members of the dinosaur clade possessed warm-blooded traits. Co-author Alessandro Chiarenza of University College London noted that maintaining this elevated internal temperature allowed the animal to thrive in cooler environments where cold-blooded animals would have struggled to survive.
Advanced Sampling Methods on Museum Specimens
Testing this paleothermometer technique on a T. rex previously posed a major logistical hurdle. Earlier versions of the isotope method required more bone material than museums were willing to cede. To overcome this limitation, the research team refined their analytical protocol, reducing the required sample size by 90 percent.
This technical breakthrough persuaded the Natural History Museum of Los Angeles to grant access to small, unexposed portions of teeth from “Thomas,” the most complete tiranosaur skeleton in its dinosaur hall. Luis Chiappe, director of research and collections at the museum, stated that weighing potential specimen damage against the value of acquiring new knowledge about the natural world justified the sampling of two teeth.
Behavioral Implications for Prehistoric Predators
Knowing the thermal regulation of Tyrannosaurus rex shapes how its behavior and ecological role are deduced. According to Eagle, a warm-blooded T. rex would be an active animal, hunting or scavenging to fuel its fast metabolism. Furthermore, these findings help clarify the chronology, demonstrating how far the ancestors of modern birds had already diverged from cold-blooded dinosaurs.
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