T. rex might not have been such a hothead after all

The most feared and iconic of all the deadly dinos might have had air conditioning built right into its skull.

Eric Mack Contributing Editor
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Eric Mack
3 min read

A graphic thermal image of a T. rex with its "cooling holes" glowing on the skull. 

University of Missouri/Brian Engh

Coping with prehistoric heat and humidity must have been tough, even for a cold-blooded thunder lizard.

New research shows that the most fearsome of the dinosaurs, Tyrannosaurus rex, may have carried around its own cooling system in its skull. 

Terrifying old T. rex had two large holes in the roof of its head bone, which scientists used to think were filled with muscles to help move its big, powerful jaw. 

But the idea never made much sense to University of Missouri School of Medicine anatomy professor Casey Holliday.

"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," Holliday said in a release.

For a closer look at what could be going on with the Swiss cheese regions of T. rex skulls, Holliday and other researchers turned to one of the closest things to dinosaurs still wandering around: alligators.

"We know that, similarly to the T. rex, alligators have holes on the roof of their skulls, and they are filled with blood vessels," said Larry Witmer, professor of anatomy at Ohio University's Heritage College of Osteopathic Medicine. "Yet, for over 100 years we've been putting muscles into a similar space with dinosaurs."  

The researchers took thermal imaging cameras to the St. Augustine Alligator Farm Zoological Park in Florida, where they found that the area around the reptiles' skull holes seemed to be hotter or colder depending on the external temperature.

"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," explained Kent Vliet from the University of Florida's Department of Biology. "This is consistent with prior evidence that alligators have a cross-current circulatory system -- or an internal thermostat, so to speak."  

The researchers believe that by studying the skull holes of living animals and comparing them to similar features in dinosaur fossils, it could overturn the long-held notion that the voids in T. rex's head are filled with muscles. Instead, they might be vents for a prehistoric AC unit. 

The complete study was published in The Anatomical Record.  

Holliday told me that the team's observations of living alligators are just a starting point and further study is needed to determine how the holes might be part of a temperature regulation system that's evolved over millions of years. 

"We cannot say for sure the directionality of temperature flow at this point. However, given the differences in heat signatures during the day and our still unclear understanding of temperature regulation in alligators, we felt confident that this device bears significance."

So please let the scientists continue to do their due diligence and do some research on this idea before anyone gets any ideas about drilling holes in their head to cool off. Consider this your daily reminder that YOU ARE NOT A REPTILE. Thank you.

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