SCIENTISTS MEASURE T. REX BODY TEMPERATURE AT 36C

Scientists at the University of California, Los Angeles have determined that Tyrannosaurus rex had a body temperature of around 36°C (97°F), close to the average human body temperature, according to a study published in the journal Science Advances. The team analysed fossilised teeth using a method that measures how atoms cluster within tooth enamel depending on an animal's body heat at the time the enamel formed. Researchers tested material from Thomas the T. rex, one of the most complete tyrannosaur skeletons held at the Natural History Museum of Los Angeles County. One account said the tests drew on portions of two teeth, while another reported that readings were taken from three teeth. The researchers said the figure shows T. rex ran considerably warmer than modern reptiles, which typically sit at 28-30°C (82-86°F).

UCLA geobiologist Robert Eagle, a co-author of the study, said the reading was "about what I would have guessed" — higher than a reptile or a slow-moving mammal such as a sloth, but lower than a bird. Co-author Aradhna Tripati, a geochemist at UCLA, said the team had spent a decade refining the technique, eventually cutting the amount of fossil material needed for testing by around 90%, which persuaded the museum to release portions of the teeth. Tripati said a body temperature of 36°C would have allowed T. rex to maintain a stable internal temperature across both cooler and warmer parts of prehistoric North America. The findings support growing evidence, researchers said, that T. rex was warm-blooded rather than a cold-blooded, sun-dependent reptile, and was instead a fast-moving predator or scavenger able to survive in climates that would have proved fatal to other reptiles. Human body temperature typically ranges from 36°C to 37°C (97°F to 99°F), while modern elephants run at a similar level to the dinosaur, researchers said.

Jasmina Wiemann, a palaeobiologist at Johns Hopkins University who was not involved in the research, said she had expected T. rex to run a few degrees hotter, closer to modern birds, which descended from dinosaurs. Wiemann said a dinosaur's temperature cannot be taken directly, meaning scientists have had to rely on indirect methods such as studying growth patterns and bone structure to estimate it. Researchers said the finding could help explain what kind of prey T. rex needed to hunt to sustain its energy requirements. The study's authors said they now intend to apply the tooth-enamel technique to other dinosaur species to establish how their body temperatures varied.