New York: For 150 years, scientists have debated the nature of dinosaurs' body temperatures and how it influenced their daily life. Now, scientists, including an Indian-origin researcher, indicate that some dinosaurs had the capacity to raise their body temperature using energy from the Sun.
These dinosaurs were probably more active than modern-day alligators and crocodiles which can be active and energetic but only for a brief time.
Led by Robert Eagle, researcher in the department of earth, planetary and space sciences at University of California-Los Angeles, the team examined fossilised dinosaur eggshells from Argentina and Mongolia.
Analysing the shells' chemistry allowed them to determine the temperature at which the eggshells formed -- information that had not been previously known.
“This technique tells you about the internal body temperature of the female dinosaur when she was ovulating,” said Aradhna Tripati, study co-author and assistant professor of geology, geochemistry and geobiology.
“This presents the first direct measurements of theropod body temperatures,” she noted.
The Argentine eggshells, which are approximately 80 million years old, are from large, long-necked titanosaur sauropods, members of a family that include the largest animals to ever roam the Earth.
The shells from Mongolia's Gobi desert, 71 million to 75 million years old, are from oviraptorid theropods, much smaller dinosaurs that were closely related to Tyrannosaurus rex and birds.
“The temperatures we measured suggest that at least some dinosaurs were not fully endotherms (warm-blooded animals) like modern birds,” Eagle said.
They may have been intermediate -- somewhere between modern alligators and crocodiles and modern birds.
“This could mean that they produced some heat internally and elevated their body temperatures above that of the environment but didn't maintain as high temperatures or as controlled temperatures as modern birds," he informed.
If dinosaurs were at least endothermic to a degree, they had more capacity to run around searching for food than an alligator would.
“The oviraptorid dinosaur body temperatures were higher than the environmental temperatures, suggesting they were not truly cold-blooded, but intermediate,” Tripati explained.
The researchers also found evidence that other dinosaurs they studied had lower body temperatures than modern birds, their only living relatives, and were probably less active.
The research was published in the journal Nature Communications