Researchers from the University of California, Los Angeles and the Natural History Museum of Los Angeles County have used a novel chemical‑signature technique on two tiny samples of a Tyrannosaurus rex tooth to estimate the dinosaur’s body temperature. The analysis, published in Science Advances, puts the temperature at roughly 97 °F (36 °C) – essentially the same range as modern humans.
How the measurement was made
The team examined isotopic bonds of carbon and oxygen preserved in the enamel of the teeth. These bonds form at rates that vary with temperature, allowing scientists to back‑calculate the temperature at which the enamel solidified over 66 million years ago. By drilling out only a few milligrams of material, the researchers avoided damaging the specimens, which are part of the nearly 70 % complete “Thomas” skeleton on display at the museum.
Implications for dinosaur biology
“This is probably the most direct constraint on a T. rex’s actual body temperature yet,” said co‑author Robert Eagle, a geobiologist at UCLA. The finding adds weight to the hypothesis that tyrannosaurs were endothermic, meaning they could regulate their internal heat and remain active in environments that would freeze cold‑blooded reptiles.
Warm‑blooded animals typically maintain higher metabolic rates, which would have allowed T. rex to hunt for longer periods and survive in the cooler climates of the Late Cretaceous, from present‑day Mexico up to Alaska. The study’s authors note that the temperature sits between that of modern reptiles (about 82‑86 °F) and the higher ranges seen in small, high‑metabolism birds (up to 104 °F).
Broader scientific context
Isotopic analysis has previously been applied to a handful of extinct species, including woolly mammoths and megalodons, but this is the first direct temperature estimate for a non‑avian dinosaur. The technique could soon be used on other iconic taxa such as Triceratops, Stegosaurus and Brachiosaurus, helping paleontologists resolve long‑standing debates about dinosaur metabolism.
“We have wondered about whether dinosaurs were warm‑blooded since the first time the name was coined,” said vertebrate paleontologist Thomas Holtz Jr. of the University of Maryland. While other lines of evidence—bone histology, biomechanics, and growth rates—have suggested endothermy, the new chemical data provide an independent line of support.
What this means for the public
Beyond academic interest, the study reshapes how we picture these ancient predators. A T. rex capable of maintaining a human‑like core temperature would have been a highly active hunter, able to pursue prey over long distances and endure colder, higher‑latitude habitats that were previously thought inhospitable to such large reptiles.
The researchers also used paleoclimate models to map potential habitats across North America during the Late Cretaceous, concluding that the species could have ranged from present‑day Mexico to Alaska. This broad distribution aligns with fossil finds of T. rex remains in both southern and northern sites.
Future directions
Lead author Aradhna Tripati, a climate scientist at UCLA, emphasized that the method’s minimal sample requirement opens the door for studying many more specimens without compromising museum collections. She added that applying the technique to early mammal ancestors could illuminate when warm‑blooded metabolism first emerged in the lineage that led to humans.
As the scientific community continues to refine these methods, our understanding of dinosaur biology—and the evolutionary pathways that led to modern birds and mammals—will become increasingly detailed.
Original reporting: El Paso News (HLL/CB) — read the source article.
