Was the T. rex really as warm-blooded as an elephant?

New tooth-chemistry analysis suggests Tyrannosaurus rex maintained a body temperature comparable to a modern elephant. Scientists infer that temperature from oxygen isotopes locked into tooth enamel as it formed, which act like a chemical record of the animal’s internal heat. A warmer-running T. rex could have sustained activity far longer than a sluggish cold-blooded predator, changing how researchers model its hunting and daily behavior. This is one line of evidence rather than the last word, but it moves the long-running metabolism debate further toward warm-bloodedness.