Tyrannosaurus rex could not interact with its environment in the same way that we humans do. Our tactile and dexterous hands allow us to manipulate objects, but T. rex – with arms infamously short compared to its gargantuan body – lacked this advantage. However, a new study from Japanese researchers reveals that the tyrannosaurs still had a sensitive side, or rather, a sensitive snout.
The experts used computed tomography (CT-Scans) to look inside the tyrant lizard king’s jaw, revealing an intricate network of neurovascular canals – pathways for nerves and blood – inside. The researchers compared this system in the extinct Tyrannosaurus rex to those present in living, or extant, animals.
“The neurovascular canal with branching pattern as complex as that of the extant crocodilians and ducks, suggests that the trigeminal nervous system in Tyrannosaurus probably functioned as a sensitive sensor in the snout,” explained study lead author Dr Soichiro Kawabe of the Institute of Dinosaur Research at Fukui Prefectural University.
These modern organisms use their sensitive jaws in a number of ways. Since crocodilians are evolutionary cousins to dinosaurs, and birds their direct descendants, paleontologists can use their behavior as a model for extinct dinosaurs, even if they can’t directly observe a living one.
“These inferences also suggest that, in addition to predation, tyrannosaurids’ jaw tips were adapted to perform a series of behaviours with fine movements including nest construction, parental care, and intraspecific communication,” said study co-author Dr. Soki Hattori.
The findings contribute to a growing body of evidence that theropods, or meat-eating, dinosaurs had sensitive faces. The carnosaur Neovenator has similar structures inside of it’s upper jaws, and fellow tyrannosaur Daspletosaurus appears to have had a similarly tactile face.
Previous studies have suggested that tyrannosaurs engaged in craniofacial biting – nipping at each other’s faces in bids for dominance or romance. This new study adds another layer to our increasing understanding of the tyrant lizards’ social lives – those love bites may have hurt a lot more than we think.
“T. rex was an even more fearsome predator than previously believed,” said Dr. Kawabe. “Our findings show the nerves in the mandible (an area of the jaw) 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 T. rex was sensitive to slight differences in material and movement; 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 T. rex as a dinosaur that was insensitive around its mouth, putting everything and anything in biting at anything and everything including bones.”
The study is published in the journal Historical Biology.