A recent study has found that the Tyrannosaurus rex, or T. rex, had a body temperature of about 97°F (36°C), which is similar to that of modern humans and elephants. This is the first direct measurement of the dinosaur's core temperature and was determined by analyzing isotopes in the teeth of T. rex fossils. Scientists looked at the bonds between rare isotopes of carbon and oxygen in the enamel. These bonds change depending on the temperature, with warm-blooded animals typically having fewer such bonds than cold-blooded animals. The research, published in the journal Science Advances, involved examining three T. rex teeth from the Hell Creek Formation in Montana. The results showed that the T. rex's body temperature was higher than that of cold-blooded reptiles but lower than that of modern birds, which typically range from 104°F to 109°F (40°C to 43°C). This suggests that T. rex was an active, fast-moving predator or scavenger, capable of surviving in a variety of climates, including cooler areas where cold-blooded reptiles would have had difficulty. Earlier studies had proposed that T. rex and its relatives were warm-blooded, but this study provides the first direct evidence of their body temperature. The findings support the idea that T. rex could regulate its internal temperature, which would have allowed it to live in a wide range of environments, from what is now Mexico to Alaska. Being able to maintain a stable body temperature would have supported a high-energy lifestyle, enabling the dinosaur to hunt or scavenge effectively. The lead researchers, including Robert Eagle from UCLA and Randy Flores, used a method that required only small amounts of fossil material, allowing them to test the technique on T. rex teeth without damaging the specimens. This discovery also helps scientists understand how T. rex evolved from cold-blooded dinosaurs and adapted to the warm conditions of the Cretaceous Period, when it lived around 68 to 66 million years ago.