Fossil Teeth Reveal T. Rex Body Temperature Was Nearly Human-Like
A new study analyzing chemical clues preserved in fossilized Tyrannosaurus rex teeth has determined that the dinosaur maintained a body temperature of approximately 97 degrees Fahrenheit—nearly identical to that of modern humans.
The research team examined isotopic signatures embedded within the enamel of T. rex teeth dating back roughly 66 million years. These chemical markers act as a kind of thermometer, preserving evidence of the animal's internal temperature at the time the tooth was forming.
The findings provide direct evidence that T. rex was warm-blooded, or endothermic—a trait that allows animals to generate their own body heat and maintain consistent temperatures regardless of their environment. This physiology would have given the massive predator significant advantages, including the ability to stay active and hunt effectively even in cooler climates.
Scientists note this is particularly significant given that T. rex fossils have been discovered as far north as Alaska, where temperatures would have been considerably cooler than in more southern regions. A warm-blooded metabolism would have allowed the predator to function effectively in these chilly environments, whereas a cold-blooded animal would have been far more limited by ambient temperatures.
The study contributes to an ongoing scientific debate about dinosaur physiology and helps explain how creatures of such enormous size were able to thrive as active apex predators across diverse ecosystems.