Scientists have wondered for decades how dinosaurs’ activity levels affected their body temperatures. Now an analysis of fossilized dinosaur eggshells from Argentina and Mongolia has revealed that dinosaurs with high body temperatures were more active and energetic predators. And those with lower body temperatures were less active. Findings of the study were published in the latest issue of the journal Nature Communications.
How researchers determined body temperatures of dinosaurs
Researchers at the University of California Los Angeles found that at least some dinosaurs were capable of raising their body temperatures with the help of heat sources in the environment, such as the sun. It’s the first time that dinosaur eggshells have been used to study the metabolism and body temperatures of dinosaurs.
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The Argentine eggshells were of long-necked, large Titanosaurs. These eggshells were approximate 80 million years old. Other eggshells unearthed from Mongolia’s Gobi desert are estimated to be 71-75 million years old, and belonged to smaller, two-legged oviraptors. Scientists led by Robert Eagle of UCLA measured the bonds between isotopes Carbon-13 and Oxygen-18 in calcium carbonate mineral of eggshells.
More bonds between the two isotopes form at low temperatures and less at hot temperatures. In case of eggshells, it reflects the body temperature of the female when the eggshells formed. Scientists found that Titanosaurs’ body temperatures were warm at 99.7 degrees Fahrenheit, but oviraptors had lower temperatures of 89.4 degrees Fahrenheit.
Some dinosaurs were not fully endotherms
Until now, most people believed that dinosaurs were either fully warm-blooded (producing heat internally) like most birds and mammals, or at an intermediate state that had not reached full endothermy. Cold-blooded animals such as lizards, crocodiles and alligators rely on external sources to regulate their body temperature. Researchers said at least some dinosaurs were not fully endotherms like modern birds.
The smaller oviraptors could have produced some heat internally and used external sources to elevate their body temperatures. In contrast, Titanosaurs were warmer because of their slow metabolism and size.