Scratches on dinosaur teeth may reveal what they consumed. Dental microwear texture analysis (DMTA) is now being used to deduce the feeding habits of large theropods such as Allosaurus and T. rex.
Researchers could deduce which dinosaurs crunched on hard bone and which ate softer foods and prey by taking 3D images of individual teeth and analyzing the pattern of marks scratched into them.
This technique opens up a new field of study for paleontologists, allowing us to better understand not only dinosaurs but also the environments and communities in which they lived.
Dinosaur teeth reveal what they didn't eat
The T. Rex from Fantasia to Jurassic Park is regarded as a terrifying apex predator capable of pursuing and devouring its prey whole, as per ScienceDaily.
But how much bone did this iconic dinosaur eat? What about other predatory dinosaurs that existed prior to it?
Dental microwear texture analysis (DMTA), a scanning technique used to examine topographical dental wear and tear in microscopic detail on individual dinosaur teeth from more than 100 million years ago, was used by researchers from the University of Tokyo in collaboration with teams from the Universities of Mainz and Hamburg in Germany to better understand what they may have eaten.
Because DMTA has primarily been used to study mammalian teeth, this is the first time it has been used to study theropods.
The same University of Tokyo team recently pioneered a study on DMTA in Japanese sauropod dinosaurs, which are known for their long necks and tails.
A high-resolution 3D image of the tooth surface was captured at a very small scale of 100 micrometers (one-tenth of a millimeter) by 100 micrometers.
The image was then analyzed using up to 50 sets of surface texture parameters, such as roughness, depth, and complexity of wear marks.
If the complexity was high, i.e., there were different-sized marks that overlaid each other, this was associated with hard object feeding, such as on bone.
The team examined 48 teeth, 34 from theropod dinosaurs and 14 from crocodilians (modern crocodiles and alligators) as a comparison.
Thanks to loans from natural history museums in Canada, the United States, Argentina, and Europe, the team was able to study original fossilized teeth and take high-resolution silicon molds.
They began researching dinosaur dental microwear in 2010, according to Graduate School of Frontier Sciences Lecturer Mugino Kubo.
He and Dr. Tai Kubo had begun collecting dental molds of dinosaurs and their contemporaries in the Americas, Europe, and, of course, Asia.
According to Daniela Winkler of the Graduate School of Frontier Sciences, what surprised them was that they didn't find much evidence of bone-crushing behavior in either Allosaurus or tyrannosaurids, despite the fact that tyrannosaurids ate the bone.
This unexpected outcome could be due to a number of factors. It is possible that, while Tyrannosaurus could eat bone, it did so less frequently than previously thought.
Also, because the team had to use well-preserved teeth, it's possible that the extremely damaged teeth that were excluded from this study were in that condition because the animals fed more on bone.
Something that the team actually found with both the dinosaurs and crocodilians was a significant difference between children and adults.
Researchers analyzed two juvenile dinosaur specimens (one Allosaurus and one tyrannosaurid) and what researchers discovered was a very different feeding niche and behavior for both compared to the adults.
Specialists discovered more wear on juvenile teeth, which could indicate that they had to feed on carcasses more frequently because they were eating leftovers, explained Winkler.
Researchers were also able to detect different feeding behavior in juvenile crocodilians, but this time it was the opposite.
Adult crocodilians had more dental wear from eating harder foods, such as larger vertebrates, while juvenile crocodilians had less dental wear from eating softer foods, such as insects.
Read more: Largest Dinosaur Species: T. Rex Might have been Bigger, Heavier than Previously Thought
What did dinosaurs eat?
The Tyrannosaurus rex was a terrifying lizard, a menacing meat-eater with a bone-crushing bite that chomped down on other dinosaurs like the Triceratops and Edmontosaurus. They most likely ate members of their own species.
But what about the more than 700 other species of dinosaur that existed millions of years ago? Meat was not on the menu for many of them.
They ate a salad instead. Jordan Mallon, a paleontologist at the Canadian Museum of Nature, claims that the vast majority of dinosaurs were herbivores, eating plant matter rather than flesh.
"In any ecosystem, you have more herbivores than carnivores," Mallon says. This holds true for both modern landscapes (where deer outnumber wolves) and ancient ecosystems. "I probably see six herbivorous dinosaurs to every one carnivore," he says of his digs, as per Popular Science.
And, surprisingly, the larger the dinosaurs were, the more likely they were to be vegetarian, he claims. Consider Sauropods.
This long-necked group includes the world's largest dinosaurs, including Argentinosaurus, the largest land animal to have ever roamed the Earth, according to some estimates, and they ate nothing but ancient plants like cycads, ferns, and ginkgos.
Related article: Dinosaur Fossil Found in Mississippi: Looks Like an Ostrich, Tall as a Giraffe