09/20/2026
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T. Rex Was Warm-Blooded! Scientists Find Clues in Fossil Teeth
A 66-million-year-old mystery
For decades, scientists have wondered whether Tyrannosaurus rex was cold-blooded like many modern reptiles or warm-blooded like birds and mammals.
Now, fossilized teeth are providing new evidence that this enormous predator maintained a surprisingly familiar body temperature.
96.8°F (36°C)
Estimated T. rex body temperature
Remarkably close to the average human body temperature of 98.6°F.
How do you take a dinosaur’s temperature?
You can’t exactly put a thermometer in a T. rex’s mouth!
Instead, researchers at the University of California, Los Angeles, examined the chemical composition of fossilized tooth enamel discovered in Montana.
Using a technique that analyzes isotopes preserved in the enamel, scientists were able to estimate the temperature at which the dinosaur’s teeth originally formed.
The results suggest that T. rex maintained an internal temperature of approximately 96.8°F.
What does this discovery tell us?
Ancient teeth hold remarkable clues
Tooth enamel can preserve chemical evidence of body temperature for millions of years, giving scientists a way to investigate the biology of extinct animals.
A warm-blooded giant
The findings support the idea that T. rex could regulate its body temperature rather than relying entirely on its surroundings for warmth.
More birdlike than we once imagined
Along with other research into dinosaur metabolism, these findings reveal important similarities between ancient dinosaurs and their living relatives: birds.
Could T. rex have survived in the Arctic?
The research suggests that T. rex may have been capable of maintaining a stable internal temperature across a wide range of climates.
That ability could have helped it survive in environments much colder than the warm prehistoric landscapes we typically associate with dinosaurs.
However, the temperature estimate alone does not establish that T. rex actually inhabited the Arctic.
So, was T. rex really a giant chicken?
Not exactly! But chickens and T. rex share a fascinating evolutionary connection.
Modern birds are living dinosaurs, and both chickens and T. rex belong to the theropod dinosaur lineage.
Although we don’t know exactly how feathered an adult T. rex was, its relatives provide evidence that feathers evolved long before modern birds appeared.
The takeaway: T. rex wasn’t simply an oversized cold-blooded lizard. Evidence from its fossilized teeth suggests it maintained a warm body temperature comparable to that of a human, adding another piece to our understanding of dinosaurs as active, complex animals.
And yes, the mighty T. rex and your backyard chicken are distant evolutionary cousins!
