Raising the Temperature on Cold-Blooded Dinosaurs

By studying the chemical composition of dinosaur teeth, scientists have determined that some sauropods had body temperatures as warm as those of mammals.

Robert Eagle, an evolutionary biologist at the California Institute of Technology, and colleagues analyzed 11 dinosaur teeth from sauropods. The researchers report their findings in the current issue of the journal Science.
Camarasaurus, a sauropod found in the United States, could reach a length of 66 feet and weigh up to 15 tons. The researchers estimated its body temperature to be about 96.3 degrees Fahrenheit.
Brachiosaurus, a larger sauropod that could grow to 75 feet and 40 tons, was even warmer, about 100.8 degrees Fahrenheit.

A normal human temperature is about 98.6 degrees Fahrenheit.
“So the first conclusion we could draw from that was that these large dinosaurs didn’t have temperatures as cold as modern crocodiles and alligators,” Dr. Eagle said.
But that does not mean that the dinosaurs had internal thermostats to keep body temperature constant independent of the environment, the way mammals and birds do. For one thing, the dinosaurs must have had “the capacity to retain environmental heat just as a function of being so large,” Dr. Eagle said. And they must have had ways to prevent themselves from overheating, he added.

“They might have had physical adaptations, like an internal air sac system, or they may have been seeking out shade in the hottest part of the day,” he said. Or they may have used their long necks and tails to release heat.
In conducting their studies, the researchers looked at the bonding between two isotopes — carbon-13 and oxygen-18 — in bioapatite, a mineral found in dinosaur teeth.
The number of bonds in the mineral correlates with the animals’ temperatures, Dr. Eagle said.
Last year, his team published a preliminary study in which they similarly determined the temperatures of crocodiles, aquarium sharks and alligators by studying dental enamel.

Source The New York Times