Dinosaurs have always been known as cold-blooded reptiles — but new research indicates that dinos may have had something in common with humans and other mammals: they could regulate their own temperature, to a degree.
A new study published in Nature Communications where researchers examined fossilized eggs has found that even though dinosaurs were technically cold blooded since they are classified as reptiles, they did have the ability to elevate their body temperature above that of the surrounding environment, according to a Washington Post report.
This was perhaps necessary due to their large size, making it more difficult to easily raise its body temperature.
Cold-blooded and warm-blooded creatures are more specifically known as ectotherms and endotherms, respectively. This study shows that dinos were a little bit of both. Humans and other mammals produce their heat internally rather than relying on the outside environment, and dinosaurs could do a little bit of that as well, which makes sense as they were the ancestors to birds, which are endothermic animals.
Of course, it varied depending on the species. Some dinosaurs had very high metabolism, while for others it was quite low. Likewise, birds have much higher rates of metabolism than that of a human, and sloths are probably on the other end of the spectrum. So it’s not specific enough to say that something is warm-blooded or cold-blooded: they fall on a scale.
Researchers from the University of California were able to examine some ancient eggshells and figure out what the temperatures of the dinosaur’s body were, and then use the soil from around that egg to estimate the temperature of the surrounding environment.
For most of the fossilized eggs, there was too much decay to get accurate readings. But for two species, they found the information they were looking for.
The long-necked titanosaur sauropod species they looked at showed an internal temperature of 100 degrees Fahrenheit, fairly similar to mammals. The second species, a Tyrannosaurus rex-type creature, was also close to mammals at a temperature of 90 degrees.
The soil in the area of the eggs, meanwhile, showed that outside temperatures were lower than this, indicating that the dinosaurs had a least some ability to generate heat endothermically.
This answers the question for scientists: were dinosaurs cold-blooded or warm-blooded? As it turns out, they’re a little of both.