Bone-crushing jaw power of T. rex greatly exaggerated

By Mark Waghorn via SWNS

The bone-crushing jaw power of Tyrannosaurus Rex has been greatly exaggerated, according to new research.

Meat-eating dinosaurs had bad teeth because they grew up feeding off scraps, scientists say.

Babies gnawed on bones left over by their parents, damaging their teeth in the process.

Unlike humans, newborns already had small, sharp incisors but they were damaged by the time they reached adolescence.

Dietary habits of the most terrifying predators that ever roamed Earth, including T. rex and Allosaurus, have been uncovered for the first time.

There was little evidence of bone-crushing in either species. Although T. rex could eat bone, it may have been uncommon behavior.

Lead author Dr. Daniela Winkler, of the University of Tokyo, said: "We studied two juvenile dinosaur specimens - one Allosaurus and one tyrannosaur.

"What we found was a very different feeding niche and behavior for both compared to the adults.

"We found there was more wear to juvenile teeth, which might mean that they had to more frequently feed on carcasses because they were eating leftovers."

The findings shed fresh light on gum disease and cavities identified in dinosaur fossils. They are based on scans of dozens of teeth.

An international team compared them with those of modern-day crocodiles and alligators.

Dr. Winkler said: "We were also able to detect different feeding behavior in juvenile crocodilians. However, this time it was the opposite.

"Juvenile crocodilians had less wear on their teeth from eating softer foods, perhaps like insects, while adults had more dental wear from eating harder foods, like larger vertebrates."

A state-of-the-art 3-D imaging technique called DMTA (dental microwear texture analysis) identified all scratches in microscopic detail.

The same results applied to Allosaurus, T. rex and another late Cretaceous theropod Lythronax which was almost as big - whose name means 'king of gore.'

Patterns of marks showed those which frequently crunched on hard bone and others that preferred softer foods and prey.

It opens up a new avenue of research for paleontology, helping us better understand dinosaurs and the environment and communities in which they lived.

In Jurassic Park, T. rex chases down prey and crunches on it whole. It had the most powerful bite of any land animal that ever lived.

Lethal dagger-like teeth - shaped like bananas - chomped down with a force of over seven tons.

Dr. Winkler said: "We wanted to test if we could use DMTA to find evidence of different feeding behaviors in tyrannosaurids from the Cretaceous period, 145 million to 66 million years ago compared to the older Allosaurus from the Jurassic period, 201 million to 145 million years ago, which are both types of theropods.

"From other research, we already knew that tyrannosaurids can crack and feed on bones from studies of their feces and bite marks on bone. But allosaurs are much older and there is not so much information about them."

DMTA has previously been used to study mammal teeth - but not theropods. The same team pioneered a study on DMTA in Japanese sauropod dinosaurs, famous for their long necks and tails.

A high-resolution 3D image was taken of the tooth surface at a very small scale of one-tenth of a millimeter by 100 micrometers in size.

Up to 50 sets of surface texture parameters were then used to analyze the image, for example, the roughness, depth and complexity of wear marks.

If the complexity was high - there were different-sized marks that overlaid each other - this was associated with hard object feeding, such as on bone.

But if the complexity was low - the marks were more arranged, of a similar size and not overlapping - this was associated with soft object feeding, like meat.

In total, the team studied 48 teeth, 34 from theropod dinosaurs and 14 from modern crocodiles and alligators, which were used as a comparison.

The team was able to study original fossilized teeth and take high-resolution silicon molds.

Co-author Dr. Mugino Kubo, also from Tokyo, said: "We actually started dental microwear research of dinosaurs in 2010.

"My husband, Dr. Tai Kubo, and I had started collecting dental moulds of dinosaurs and their contemporaries in North and South Americas, Europe, and of course Asia.

"Since Daniela joined my lab, we utilized these molds to make a broader comparison among carnivorous dinosaurs."

Added Dr. Winkler: "It was especially challenging to carry out this research during the pandemic, as we rely on being able to gather samples from international institutions. The sample size might not be so large this time, but it is a starting point."

The next step will be to look in more detail at the long-necked sauropods, which the team has also been studying.

But for now, Dr. Winkler is experimenting with something much, much smaller. Insects' mouths are tiny and don’t have any teeth.

The researchers want to see if they can still find evidence of mouth wear using the same technique.

Added Dr. Winkler: "From what we learn using DMTA, we can possibly reconstruct extinct animals' diets, and from this make inferences about extinct ecosystems, paleoecology and paleoclimate, and how it differs from today.

"But this research is also about curiosity. We want to form a clearer image of what dinosaurs were really like and how they lived all those millions of years ago."

The study was published in the journal Palaeontology.