Scientists have studied the teeth of Tyrannosaurus rex, a famous meat-eating dinosaur, and found that it probably had a body temperature of about 36.3°C. This is almost the same as the average human body temperature. The study looked at fossilised T. rex teeth found in Montana, USA. The enamel, or hard outside layer of the teeth, can show what body temperature the dinosaur had when it was alive.

The main reason for this research was to find out if T. rex was warm-blooded. Warm-blooded animals, like humans and birds, keep their bodies warm inside even when it is cold outside. Scientists tested the T. rex tooth enamel and compared it to teeth from ancient crocodiles found in the same place. The crocodile teeth showed a lower temperature, more like modern reptiles.

Because of this finding, scientists now believe that T. rex was warm-blooded, not cold-blooded like lizards. This means T. rex could stay active in cold weather. It also needed more food to keep warm, so it had to hunt more. These results help us better understand how T. rex lived.