T. rex’s jaw had sensors that made it an even more formidable predator

Tyrannosaurus rex wasn’t just a huge beast with a big bite, it had nerve sensors at the end of its jaw that allowed it to better detect – and eat – its prey, a new study published in the peer-reviewed journal Historical Biology found today.

“T. rex was an even more formidable predator than previously believed,” says lead author Dr Soichiro Kawabe of the Dinosaur Research Institute at Fukui Prefectural University in Japan.

“Our results show that the nerves of the mandible (an area of ​​the jaw) of Tyrannosaurus rex are more complexly distributed than those of any other dinosaur studied to date, and comparable to those of modern crocodiles and tactile foraging birds, that have extremely keen senses.

“What this means is that T. rex was sensitive to slight differences in material and movement; this indicates the possibility that it was able to recognize different parts of their prey and eat them differently depending on the situation. .

“It completely changes our perception of T. rex as a callous dinosaur around its mouth, putting anything and everything while biting anything and everything, including bones.”

While the morphology of jaw vessels and nerves has been analyzed in several fossil reptiles, this study is the very first study of the internal structure of the T. rex mandible.

Dr Kawabe, who was joined by Dr Soki Hattori, assistant professor at the Institute of Dinosaur Research, used computed tomography (CT) to analyze and reconstruct the neurovascular distribution channel of a fossil mandible of T. rex, which was originally found in hell. Creek Formation, Montana.

They then compared their reconstruction to other dinosaurs such as the Triceratops, as well as living crocodiles and birds.

This allowed the researchers to describe the well-preserved canals that house the dental vessels and nerves of Tyrannosaurus rex.

“The present study reveals the presence of neurovascular channels with complex branching in the lower jaw of Tyrannosaurus, particularly in the anterior region of the tooth, and it is speculated that a similarly complex branched neurovascular channel would also be present in his upper jaw. ” Dr Kawabe said.

He added: “The neurovascular channel with a branching pattern as complex as that of extant crocodilians and ducks suggests that the Tyrannosaurus trigeminal nervous system likely functioned as a sensitive sensor in the snout.

“It should be noted that the muzzle sensitivity of the Tyrannosaurus may not have been as improved as that of the crocodilians because the Tyrannosaurus does not have the thick neural tissue occupying the neurovascular canal unlike existing crocodiles.

“Nonetheless, the muzzle sensitivity of the Tyrannosaurus was considerably higher than that of the Ornithischian dinosaurs compared in this study.”

The results of the article are consistent with analyzes of the skull surface of another tyrannosaurid, Daspletosaurus, and the morphology of the neurovascular channel in the jawbone of the Neovenator allosaurid, which indicate that the facial area of ​​theropods may have been very sensitive.

“These inferences also suggest that in addition to predation, the jaw tips of tyrannosaurids were adapted to perform a series of behaviors with fine movements, including nest building, parental care and intraspecies communication,” adds the Dr Hattori.

Limitations of the study include the team’s lack of analysis of the entire mandible area of ​​T. rex and other dinosaurs used for comparison, but since the unstudied proportion is insignificant, the trend indicated “should be a reasonable estimate”.