T. Rex Teeth Suggest it Had a Body Temperature Like Humans
WHO:
Cowboy State Daily - Paleontologist Paul Sereno stated, “I was told this might be an extraordinary specimen,” regarding Rex Junior.
Science Daily - T. rex, a giant predator dinosaur.
WHAT:
Cowboy State Daily - Rex Junior is a partial skeleton of a sub-adult T. rex found on the Zerbst Ranch near Newcastle, Wyoming.
Cowboy State Daily - The main concretion containing Rex Junior weighed over 5,000 pounds, with subsidiary pieces around 2,000 pounds.
Cowboy State Daily - The articulated right arm of Rex Junior is the only complete T. rex hand and forearm ever found.
Science Daily - T. rex maintained a body temperature of about 97 degrees Fahrenheit.
Ars Technica - Isotope ratios in T. rex teeth suggest the dinosaur was actively managing its body temperature.
WHERE:
Science Daily - T. rex lived in environments as far north as Alaska.
WHY:
Cowboy State Daily - Sereno believes Rex Junior was buried alive in a flood, as it appears to be perfectly three-dimensionally preserved, unlike typical mummified specimens.
Science Daily - The finding provides direct evidence that T. rex was warm-blooded, which helps explain how it stayed active and survived in chilly environments.
HOW:
Cowboy State Daily - Rex Junior was removed from the Zerbst Ranch using a 17-foot U-Haul truck after being wrapped in plaster and wood for transport.
Cowboy State Daily - The preparation of Rex Junior is ongoing, with the primary 5,000-pound concretion mostly prepared on one side, revealing the right arm and most of the ribcage.
Science Daily - Chemical clues preserved inside fossilized T. rex teeth were analyzed to determine body temperature.
(UPDATED September 20, 2026 15:56 UTC)
Paleontologist Paul Sereno has described Rex Junior as an extraordinary specimen, which is a partial skeleton of a sub-adult T. rex discovered on the Zerbst Ranch near Newcastle, Wyoming. The main concretion containing Rex Junior weighs over 5,000 pounds and includes the only complete T. rex hand and forearm ever found, while the ongoing preparation has revealed the right arm and most of the ribcage. Sereno suggests that Rex Junior was buried alive in a flood, as its preservation is remarkably three-dimensional compared to typical mummified specimens.
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(UPDATED September 20, 2026 13:58 UTC)
Scientists have discovered that T. rex, the giant predator dinosaur, maintained a body temperature of about 97 degrees Fahrenheit, suggesting it was warm-blooded. This finding, based on the analysis of chemical clues preserved in fossilized T. rex teeth, provides direct evidence of how the dinosaur managed its body temperature while living in environments as far north as Alaska. The ability to stay active in chilly climates helps explain how T. rex thrived in such diverse habitats.