T. Rex’s bone-crushing bite was 160 million years in the making

By Mark Waghorn via SWNS

Tyrannosaurus Rex's notorious bone-crushing bite was more than 160 million years in the making, according to new research.

Theropods' jaws became stronger as they evolved - allowing them to eat tougher food.

The 'king of the dinosaurs' had the most powerful bite of any land animal that ever lived.

Its lethal dagger-like teeth - shaped like bananas - chomped down on prey with a force of over seven tons.

How T. Rex performed the feat - without smashing its own skull - has baffled scientists for decades.

Now a British-led team has solved the mystery - using computer modeling and simulations.

The rear of the jaw gradually expanded in all groups - including flesh and plant eaters.

It also became deeper and upturned in the carnivores - but downturned in the herbivores.

The phenomenon fuelled their diversification and led to the emergence of modern birds - which descended from dinosaurs.

Biomechanical analysis showed the changes made jaws mechanically more stable - minimizing the risk of bone fracture during biting.

Lead author Fion Waisum Ma, a Ph.D. student at the University of Birmingham, said: "Theropod dinosaurs are always depicted as fearsome predators in popular culture.

"But they are in fact very diverse in terms of diets. It is interesting to observe the jaws becoming structurally stronger over time, in both carnivores and herbivores.

"This gives them the capacity to exploit a wider range of food items. Theropod dinosaurs underwent extreme dietary changes during their evolutionary history of 165 million years.

"They started off as carnivores, later on evolving into more specialized carnivores, omnivores and herbivores.

"Studying how their feeding mechanics changed is key to understanding the dietary transitions in other vertebrate animals too."

T. Rex first appeared 69 million years ago, going extinct 2.5 million years later. Its earliest ancestor dates back 230 million years.

The researchers created digital versions of more than 40 lower jaws from five different types of theropods.

They included T. Rex and Velociraptor along with lesser-known herbivores such as ornithomimosaurs, therizinosaurs and oviraptorosaurs.

In carnivores like tyrannosauroids, an early form like Guanlong had a relatively slender and straight jaw.

But Tyrannosaurus, Tarbosaurus and other later members evolved more cavernous jaws with the front bending up - which increases strength.

Plant-eating counterparts experienced considerable stress from repetitive munching on coarse vegetation.

The jaws of herbivores like Erlikosaurus and Caudipteryx bent sharply downwards - helping dissipate such pressure.

Senior author Dr. Stephan Lautenschlager, also from Birmingham, said: "It is fascinating to see how theropod dinosaurs had evolved different strategies to increase jaw stability depending on their diet.

"This was achieved through bone remodeling - a mechanism where bone is deposited in regions of the jaw that experience high stresses during feeding."

Ms. Waisum Ma and colleagues also looked at the feeding styles of tyrannosaurids through growth.

They found the deeper and more upturned jaws of T. Rex were structurally stronger in adulthood compared to adolescence.

Added Dr. Lautenschlager: "The similarity between jaw strengthening through growth and through time suggests developmental patterns in juvenile dinosaurs ultimately affected the evolution of the whole group.

"This likely facilitated the jaw evolution of theropod dinosaurs and their overall success for over 150 million years."

T. Rex was among the largest land predators to roam Earth. It reached 40 feet long, 12 feet tall and weighed over eight tons.

The findings in Current Biology explain a paradox - how the creature crushed other animals' bones without breaking its own in the process.

Teeth, jaws and skulls are all made of bone. Gnashing and bashing bones together would have resulted in fractures all around without the unique adaptations.