Overview
- The UCLA-led study published Wednesday, Sept. 16, 2026 reconstructed T. rex internal temperature at about 97.3°F (36.3°C ±2.5°C) from three fossil teeth, two of which came from the Natural History Museum of Los Angeles County specimen nicknamed Thomas.
- Researchers used a refined clumped‑isotope method that cuts required enamel sample size by roughly 90 percent so only a few milligrams of tooth were needed and museums could permit minimally destructive sampling.
- Controls from five crocodilian teeth from the same Hell Creek–type deposits recorded substantially lower temperatures (about 87.6°F), which supports the interpretation that the T. rex signal reflects biologically generated heat rather than ambient conditions.
- The measured temperature places T. rex in a warm‑blooded physiological range that implies higher metabolic rates, greater food needs, improved stamina, and the ability to live across broad latitudes including high‑latitude regions.
- Authors and external experts caution this result applies to T. rex and related theropods rather than all dinosaurs, and the team plans to apply the technique to more taxa to map the diversity of dinosaur thermoregulation.