T-Rex Had An Air Conditioner Built Into Its Head, Say Scientists


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockSep 6 2019, 10:35 UTC

Artist's impression of a graphic thermal image of a T. rex with its dorsotemporal fenestra glowing on the skull. Illustration courtesy of Brian Engh

T-rex was a formidable animal and thanks to movies like Jurassic Park, it has become almost a quintessential dinosaur. Despite our familiarity with them, there is still a lot left to learn about these extinct giants and new ideas are challenging some existing wisdom.

As reported in The Anatomical Record, a team of researchers is reconsidering the role of the dorsotemporal fenestra, the two large holes found in the roof of the T-rex’s skull. The study argues that the holes were used by the dinosaur to regulate its body temperature. This goes against the idea that these holes were filled with muscles to assist the movement of the predator's powerful jaw. 


"It's really weird for a muscle to come up from the jaw, make a 90-degree turn, and go along the roof of the skull," lead researcher Professor Casey Holliday, from the University of Missouri, said in a statement. "Yet, we now have a lot of compelling evidence for blood vessels in this area, based on our work with alligators and other reptiles."

Skull and neck of a T-rex. Puwadol Jaturawutthichai/Shutterstock

Alligators have holes in the roof of their skulls that are filled with blood vessels. The reptiles, whose ancestors roamed the Earth far earlier than the T-rex, use these holes for thermoregulation since their internal temperature depends on how hot or cold it is outside.

"An alligator's body heat depends on its environment," said Kent Vliet, coordinator of laboratories at the University of Florida's Department of Biology. "Therefore, we noticed when it was cooler and the alligators are trying to warm up, our thermal imaging showed big hot spots in these holes in the roof of their skull, indicating a rise in temperature. Yet, later in the day when it's warmer, the holes appear dark, like they were turned off to keep cool. This is consistent with prior evidence that alligators have a cross-current circulatory system – or an internal thermostat, so to speak."


The team investigated fossilized remains of alligators and tyrannosaurs and looked at similarities between their dorsotemporal fenestra. Based on their analysis, the team believes that the holes in the skulls of T-rexes and other non-avian dinosaurs may have been filled with fat tissues and blood vessels as they are in ancient and modern gators. This system would have acted like a built-in air conditioner to regulate the body temperature of T-rex.