Skulls belonging to T-Rexes have always been found with two large holes at the temple. These holes, known as dorsotemporal fenestra (“fenestra” is Latin for “window”), were thought to be sites of jaw muscle attachments. But a recent study has hypothesized that these holes may have had a radically different function: they may have aided in thermal regulation instead for the king of the dinosaurs.

The researchers used thermal imaging on reptiles, specifically alligators, which also have dorsotemporal fenestra. When the temperature outside was cool, and alligators needed to warm up, thermal imaging showed these two large holes get warm. Inversely, when the temperature outside was too hot, thermal imaging showed these two holes become cold, as to keep the alligators cool.

Kent Vilet, one of the study’s authors, comprares the alligators’–and by extension the T-Rex’s– cross-current circulatory system to “an internal thermostat, so to speak.”

This kind of study is a perfect example of how the current analogues of extinct animals can be used to solve anatomical and other paleontological mysteries.

Dinosaurs were warm-blooded reptiles, and a gargantuan creature such as a T-Rex would have generated an immense amount of heat. These two holes would have acted as an “air conditioner” for the skull. It is also hypothesized that T-Rexes may have panted, much like birds, alligators, and dogs do to cool off.

Since, according to this study, the dorsotemporal fenestra are no longer seen as sites for jaw muscle attachments, it can be concluded that the bite force of a T-Rex may have been smaller than previously assumed.

Information for this post was taken from CNN.