Researchers analyzing fossilized teeth have determined that Tyrannosaurus rex maintained an average body temperature of 97.3 degrees Fahrenheit, comparable to modern elephants and humans. Published in Science Advances, the findings indicate the apex predator was warm-blooded, providing new insights into how it survived northern winters and dominated ancient ecosystems.
Isotope Thermometry Reveals a Human-Like Body Temperature
Scientists have long debated whether the king of the dinosaurs operated more like a sluggish, sun-basking reptile or an active, energy-demanding endotherm. A research team led by University of California, Los Angeles geochemist Aradhna Tripati calculated the average body temperature of the prehistoric creature at about 36.3 degrees Celsius, or 97.3 degrees Fahrenheit. This research was published in Science Advances. A research team led by Aradhna Tripati, a professor of Earth sciences at the University of California, Los Angeles (UCLA), published their findings on estimating Tyrannosaurus body temperature from its teeth in the international journal Science Advances on the 16th (local time). By analyzing the chemical composition of fossilized teeth, researchers directly estimated the body temperature of T. rex and concluded that, unlike modern reptiles, dinosaurs were likely closer to endothermic animals
that actively maintain a high internal temperature.
The measurement was achieved using a technique that involves the use of rare types of carbon and oxygen molecules called isotopes. The authors analyzed Tyrannosaurus rex teeth from Montana, USA. The technique measures the bonding patterns of carbon and oxygen atoms in tooth enamel to determine the temperature at which the mineral formed. Co-author Robert Eagle, a geobiologist and associate professor at UCLA, remarked on the significance of this method as possibly the most direct and least complicated
means of determining T. rex’s actual body temperature.
Tyrannosaurus rex is perhaps the most intensely studied dinosaur owing to a relatively well-sampled record, earning it the status of an exemplar organism that is commonly referenced in studies of vertebrate paleontology,
said University of California-Los Angeles geobiologist Robert Eagle and his colleagues. “Aspects of the biology and ecology of Tyrannosaurus rex, which provide evidence for an endothermic thermophysiology, include locomotor costs, growth rates, and geographic distribution, yet confident estimates of body temperature are lacking.”
How Warm-Blooded Biology Fueled an Arctic Survivor
Maintaining an internal temperature well above the surrounding environment gave the predator distinct ecological advantages. Fossil evidence found in the northern areas, such as Alaska, hinted that the massive dinosaur could live in places where today’s reptiles would find it hard to exist. At that time in late Cretaceous, North America was warmer than today. However, in the north, there were seasonal colds and some areas of ancient Alaska had periods of limited light. Recent discoveries, notably including a fossilized footprint found in Alaska in 2022, have bolstered this theory.
By generating and regulating its own body heat, Tyrannosaurus rex could operate independently of external sunshine. That metabolic efficiency refutes the older perception of the dinosaur as a slow creature reliant entirely on ambient warmth. Jasmina Wiemann, an associate professor of Earth and planetary sciences at Johns Hopkins University who had no role in the latest work, noted, We can’t just use a thermometer to do that.
Contrasting the Apex Predator With Its Contemporaries
The results pointed to an average body temperature of about 36.3 degrees Celsius, comparable to living large mammals such as elephants. Dinosaurs were long regarded as ectothermic animals
whose body temperature varies with the external environment, like lizards or crocodiles, but paleontologists’ views have been changing in recent years. There is now a growing argument that dinosaurs were endothermic animals,
like mammals, rather than ectotherms.
The thermal gap between the apex predator and its reptile neighbors underscores a fundamental physiological division. While crocodilians relied on external heat, the dinosaur sustained a core temperature similar to modern large mammals like elephants.
Metabolic Costs and the Hunt for Prey
A warm-blooded physiology comes with heavy biological obligations. Endotherms require significantly more energy than ectotherms, meaning an elevated body temperature directly increased its need for food and constant hunting. The technique used in this research has previously been applied to various extinct species, including other dinosaurs and large mammals like woolly mammoths. It provides vital insights into how extinct animals survived.
Next Steps in Prehistoric Physiology
We figured out how warm the most famous animal of all, a T. rex, was,
said co-author Aradhna Tripati, a geochemist at the University of California, Los Angeles. Readings from teeth revealed an average body temperature of about 97 degrees Fahrenheit (36 degrees Celsius). That’s similar to modern elephants and not too far from the average body temperature of humans.
