Sixty-six million years after its last breath, Tyrannosaurus rex has offered up a quiet confession locked inside its teeth: it ran warm. Scientists analyzing isotopic ratios in fossilized tooth enamel have measured the great predator's body temperature at roughly 97 degrees Fahrenheit — a figure that places it alongside humans and elephants in the thermal company of the living. In doing so, a single chemical signature has begun to dissolve one of paleontology's most enduring assumptions, suggesting that the most iconic predator in Earth's history was not a cold-blooded giant waiting for the su