Fossils: T. rex had complex nerve sensors at the end of its jaws, study finds

Tyrannosaurus rex – the often nicknamed “king of the dinosaurs” had nerves in his jaw that would have allowed him to recognize various parts of his prey and eat them differently.

That’s the conclusion of experts from Fukui Prefectural University, who scanned the fossilized lower jaw of a T. rex and reconstructed the nerve pattern inside.

The formidable reptiles may also have been skilled enough with their mouths to use them to make nests, care for their young, and even communicate with each other.

While the internal structure of the jaw has already been studied in several fossil reptiles, this is the first such study to focus on T. rex, the team said.

‘T. rex was an even more formidable predator than previously believed, ”said article author and dinosaur paleontologist Soichiro Kawabe of 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.”

In fact, he continued, it is “comparable to those of modern crocodiles and tactile foraging birds, which have extremely keen senses.

“What this means is that T. rex was sensitive to slight differences in matter and movement. This indicates the possibility that he 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.”

Dr Kawabe and his colleagues used computed tomography (CT) scans to reconstruct the “neurovascular channel” of blood vessels and nerves crossing the fossil lower jaw of a T. rex unearthed from the Hell Creek rock formation in Montana.

They then compared their three-dimensional reconstruction to that of other dinosaurs – including the Triceratops – as well as to the neurovascular canal of living bird and crocodile species.

The team found that T. rex’s neurovascular channels have complex branches, especially in the front of the mouth.

“It is speculated that an equally complex branched neurovascular channel is also present in his upper jaw,” Dr Kawabe said.

“The vasculo-nervous canal – 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.”

According to the team, the channel they revealed in the T. rex fossil was similar to that of another therapist, the allosaurid, suggesting they may all have very sensitive faces.

“It should be noted that the muzzle sensitivity of the Tyrannosaurus may not have been as improved as that of the crocodilians, as the Tyrannosaurus lacks thick neural tissue. [in] the neurovascular channel, unlike existing crocodiles, ”said Dr Hattori.

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

(Ornithischian dinosaurs were those, like triceratops, that had a pelvis similar to those seen in modern birds.)

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

The full results of the study were published in the journal Historical Biology.