Tyrannosaurus rex’s Jaw Tip May Have Played Essential Role as Sensitive Tactile Sensor
Paleontologists have analyzed the morphology of the neurovascular canal in the well-preserved jaw of Tyrannosaurus rex using computed tomography techniques. Their results show that the dinosaur’s neurovascular canal had a rather complex branching amongst the dinosaurs and that its complexity was comparable to that of living crocodiles and tactile-foraging birds.
“Tyrannosaurus rex was an even more fearsome predator than previously believed,” said Dr. Soichiro Kawabe, a paleontologist in the Institute of Dinosaur Research at Fukui Prefectural University.
“Our findings show the nerves in the mandible of Tyrannosaurus rex is more complexly distributed than those of any other dinosaurs studied to date, and comparable to those of modern-day crocodiles and tactile-foraging birds, which have extremely keen senses.”
“What this means is that Tyrannosaurus rex was sensitive to slight differences in material and movement,” he added.
“It indicates the possibility that it was able to recognize the different parts of their prey and eat them differently depending on the situation.”
“This completely changes our perception of Tyrannosaurus rex as a dinosaur that was insensitive around its mouth, putting everything and anything in biting at anything and everything including bones.”
Using computed tomography, Dr. Kawabeto and Dr. Soki Hattori, also from the Institute of Dinosaur Research at Fukui Prefectural University, analyzed the neurovascular canal in a fossil lower jaw of Tyrannosaurus rex.
The specimen was originally collected from the Hell Creek Formation in Montana, the United States.
The paleontologists then compared their reconstruction to other dinosaurs such as Triceratops, as well as living crocodiles and birds.
“Our study reveals the presence of neurovascular canals with complex branching in the lower jaw of Tyrannosaurus rex, especially in the anterior region of the dentary, and it is assumed that a similarly complex branching neurovascular canal would also be present in its upper jaw,” Dr. Kawabe said.
“The neurovascular canal with branching pattern as complex as that of the extant crocodilians and ducks, suggests that the trigeminal nervous system in Tyrannosaurus rex probably functioned as a sensitive sensor in the snout.”
“It must be noted that the sensitivity of the snout in Tyrannosaurus rex may not have been as enhanced as that of the crocodilians because Tyrannosaurus rex lacks the thick neural tissue occupying the neurovascular canal unlike extant crocodiles.”
“Nevertheless, the sensitivity of the snout of Tyrannosaurus rex was considerably greater than that of the ornithischian dinosaurs compared in this study.”
The new results are consistent with analyses of the skull surface of another tyrannosaurid dinosaur, Daspletosaurus, and the allosaurid dinosaur Neovenator, which indicate that the facial area of all theropod dinosaurs may have been highly sensitive.
“These inferences also suggest that, in addition to predation, tyrannosaurids’ jaw tips were adapted to perform a series of behaviors with fine movements including nest construction, parental care, and intraspecific communication,” Dr. Hattori said.
The findings were published in the journal Historical Biology.
Soichiro Kawabe & Soki Hattori. Complex neurovascular system in the dentary of Tyrannosaurus. Historical Biology, published online August 22, 2021; doi: 10.1080/08912963.2021.1965137