Was the Tyrannosaurus Rex a foodie?
The dinosaur, fixated in the popular imagination as a ruthless predator that chewed on every unfortunate creature that crossed its path, actually had a jaw full of nerve endings that made it a more judicious eater than previously known, according to paleontologists in Japan who published their findings in Historical Journal. Biology on Monday.
While it may not have been a particularly discerning gastronome, the T. Rex had a refined lower jaw similar to the jaws of modern crocodiles and tactile foraging birds, such as ducks, according to scientists at the Institute of Dinosaur Research in Fukui University Prefecture, who conducted the investigation.
In other words, T. Rex most likely wasn’t eating blindly, according to the study. It had keen senses that would have allowed it to recognize different parts of its prey and chew it differently depending on what it was chewing.
“Tyrannosaurus’ jaws were powerful enough to crush bones,” Soichiro Kawabe, one of the study’s authors and a paleontologist at the institute, said in an email. “In situations where food was plentiful, they may have used their sensitive snouts to selectively eat the more nutritious parts of their prey. Tyrannosaurus’ diet may not have been as rough as we imagine.”
The study doesn’t say how distinctive the T. Rex was or whether it could recognize the difference between bone and flesh.
“These speculations are quite imaginary and are not within the scope of what we can scientifically deduce from our research results,” said Dr. kawabe.
The significance of the study is that it reveals the complex development of nerves in the Tyrannosaurus’ lower jaw, he said.
“Based on the morphology of Tyrannosaurus’ mandibular nerve, we were able to clarify that Tyrannosaurus’ jaw tip was most likely a pretty capable sensor,” said Dr. kawabe.
dr. Kawabe and another scientist, Soki Hattori, an assistant professor at the institute, used computed tomography, or CT scanning, to analyze and reconstruct the canal structure of the jawbone through which nerves and blood vessels would have passed. They studied the fossil of a T. Rex found in the Hell Creek Formation in Montana.
The fossil was well preserved, allowing the researchers to study the channel structure, he said.
The sensitive jaw points also provide clues as to how the Tyrannosaurus may have grown up.
Crocodiles have a sensitive snout, which helps them detect prey in the water, but also gives them such a finely tuned sense of touch that they can carry their young in their mouths without crushing them with their powerful jaws.
“Tyrannosaurus may have done the same,” said Dr. kawabe.
The study underscores “the sensitive side of the T. Rex,” said Jack Tseng, a paleontologist at the University of California, Berkeley, who read the report.
“We’re really obsessed with the powers the T. Rex might possess rather than its finesse,” he said. “This gives us a sense of finesse.”
The report gives “another dimension” to a creature that the general public is obsessed with but rarely seen as anything more than a monster, said Dr. Tseng, who analyzed the bite of the teenage Tyrannosaurus.
“They weren’t dumbass chewing on everything they saw moving,” he said.
Yet said Dr. Tseng said the study’s findings underscore the need for more fossil evidence to show how the dinosaur’s sensitive lower jaw was used. Analyzing coprolites, or fossilized feces, “could be another way to understand how sensitive their palates were,” he said.
The report’s authors acknowledged that their findings are limited: They have not analyzed the entire dinosaur mandible region or used other dinosaur fossils for comparison.
“Ideally, this study could be continued with a variety of additional dinosaur species, to see if Tyrannosaurus was truly exceptional, or just an ordinary carnivorous dinosaur,” said Thomas R. Holtz, a paleontologist at the University of Maryland who read the study. . “But even this small-scale study helps us better understand dinosaurs as living, sentient animals.”