Scientists previously thought that the roof of the tyrannosaurus rex's skull had two large holes known as dorsotemporal fenestra that were filled with muscles to help the dinosaurs with jaw movements.

Alligators, Crocodiles, And The T. Rex Have Large Holes In Their Skull

Casey Holliday, a professor of anatomy at the University of Missouri School of Medicine, and colleagues, however, have found evidence that offers new insights into the T.rex's head.

In their study published in The Anatomical Record on July 1, the researchers examined alligators using thermal imaging, which translates heat into visible light. Like the T.rex, alligators, and crocodiles also have holes on the roof of their skulls.

The head of an alligator's body is dependent on the environment. The researchers noticed that when it was cooler and the animals were trying to warm up, thermal imaging showed big hot spots in the holes in the alligators' skull, which indicate a rise in temperature.

Later in the day when it was warmer, the researchers observed that the holes appeared dark as if they were turned off to keep the animals cool.

Holiday and colleagues then matched the thermal imaging data from the dinosaurs with those of the T.rex fossils, to see how the two holes evolved overtime.

The study revealed that the holes on the roof of the T.rex skulls were filled with blood vessels, challenging earlier hypotheses about the anatomy of the prehistoric predator's head.

"Relevant anatomical features argue for rejection of the default hypothesis-that the fossa was muscular-due to a complete lack of osteological correlates reflective of muscle attachment. The most‐supported inference of soft tissues is that the frontoparietal fossa contained a large vascular structure and adipose tissue," the researchers wrote in their study.

Built-in Airconditioner To Keep T.Rex Dinosaurs Cool

Holiday explained that land predators like the T.rex would have needed the ability to shed heat because it generated a lot of body heat. A"thermal window" in their head would have helped. The special set of blood vessels in their skull could have acted as a way to regulate the temperature of their body and brain.

"Dinosaurs were likely more warm-blooded than we used to think, more like birds than lizards," Holliday told CNN. "Being warmish-blooded would let them not rely on environmental temperatures as much, like cold-blooded lizards, but also control their body temp through internal means."

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