T. rex tooth isotope analysis suggests body temperature similar to elephants

Isotope analyses of fossilized remains have revealed that several extinct giant species may have actively regulated their body temperatures. Researchers examined the ratios of oxygen‑18 to oxygen‑16 in bone phosphate and tooth enamel from specimens ranging from the Late Cretaceous to the Pleistocene. The measured values deviate from those expected in strictly ectothermic organisms, suggesting a physiological mechanism for maintaining a relatively stable internal climate despite fluctuating external conditions.

The study, conducted by an international team of paleobiologists and geochemists, compared the isotopic signatures of the giants with those of contemporary ectotherms and endotherms. By calibrating the data against known temperature-dependent fractionation patterns, the scientists inferred that the large vertebrates could have employed behavioral or metabolic strategies—such as basking, burrowing, or elevated metabolic rates—to modulate their thermal environment. These findings provide a new line of evidence for complex thermoregulatory adaptations in megafauna, expanding current understanding of their ecology and evolutionary success.

The results underscore the value of isotopic proxies in reconstructing the physiology of extinct organisms and may prompt revisions to models of ancient ecosystems. Further investigations are planned to assess whether similar temperature‑management mechanisms were present across other giant taxa and to explore the broader implications for climate resilience in prehistoric megafaunal communities.