Dinosaur body temperatures widely varied, according to a new study that used dino eggshells to determine how hot, or not, some dinosaurs were.
The new research in the journal Nature Communications, represents the first time that dinosaur eggshells have been used to figure out the body temperature and metabolism of dinosaurs.
The research concluded that titanosaurs -- huge long-necked, plant-eating dinosaurs -- were hotter than humans, measuring out at 99.7 degrees Fahrenheit. Smaller, two-legged omnivorous oviraptors were estimated to have had a body temperature of 89.4 degrees Fahrenheit.
Top 10 Largest Dinosaurs
"Many people now think, based on current work, that dinosaurs were either fully endothermic (warm-blooded and producing heat internally) like most modern mammals and birds, or at a kind of intermediate physiological state and had not reached full endothermy," explained lead author Robert Eagle, who is a researcher at the University of California at Los Angeles' Institute of the Environment and Sustainability.
Eagle, who is also LabEx International Chair of the European Institute of Marine Sciences, and his colleagues measured the bonds between two heavy isotopes, Carbon-13 and Oxygen-18, in the calcium carbonate mineral that makes up the hard part of eggshells.
He explained, "The abundance of these bonds in calcium carbonate is related to the temperature the mineral forms at, with more bonds forming at cold temperatures and less at hot. In the case of eggshells, the abundance of these bonds reflects the body temperature of the female when the eggshell forms."
Photos: Dinosaur Blood and Bone Cells Found
The scientists took the measurements for both eggs of living dinosaurs, i.e. birds, as well as for eggs of now-extinct dinosaurs. Several eggs did not retain their original chemical composition, but the researchers believe they did get accurate readings for titanosaurs and oviraptors.
Both types of dinosaurs lived during the Upper Cretaceous roughly 70-80 million years ago.