Study Finds T. rex Had Body Temperature Similar to Modern Animals

NEW YORK (AP) — Using fossilized teeth, scientists have determined that the body temperature of Tyrannosaurus rex was similar to that of modern animals. Researchers previously believed that dinosaurs were cold-blooded, but later studies suggested that some were warm-blooded and could regulate their body temperature. Most scientists now agree that T. rex was warm-blooded, but accurately measuring the core temperature of an extinct species presents challenges. "We can't just use a thermometer to do that," said Jasmina Wiemann, a paleobiologist at Johns Hopkins University who did not participate in the study. Previous methods, such as examining T. rex growth patterns and bone structure, did not yield definitive results. In a new study, researchers analyzed chemical clues found in the teeth of T. rex. The arrangement of atoms within the enamel varies according to an animal's body temperature. "We figured out how warm the most famous animal of all, a T. rex, was," said co-author Aradhna Tripati, a geochemist at the University of California, Los Angeles. Measurements from three teeth indicated an average body temperature of approximately 97 degrees Fahrenheit (36 degrees Celsius), comparable to modern elephants and close to the average human body temperature, which ranges from 97 to 99 degrees Fahrenheit (36 to 37 degrees Celsius). The study was published in the journal Science Advances. Wiemann expressed surprise at the findings, noting she expected a higher body temperature based on her previous research, which suggested that T. rex might have been similar to modern birds, which are descendants of dinosaurs. Understanding the body temperature of T. rex could provide insights into its lifestyle and habitat. At 97 degrees (36 degrees Celsius), T. rex could have thrived across much of prehistoric North America, adapting to both cooler and warmer climates. The research may also inform scientists about the types of prey T. rex needed to hunt to sustain its energy levels. Researchers emphasize the importance of applying these methods to other dinosaur species to further explore their thermal regulation. "There's lots of interesting, charismatic species that could be explored using this," said study co-author Robert Eagle, a geobiologist at UCLA.