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Secret behind T. rex’s bone-crushing bite revealed

"Dinosaurs evolved different eye socket shapes to allow stronger bites. They were all the better to better eat you with."


T.rex had the most powerful bite of any land animal that ever lived. (Wikimedia Commons)

By Mark Waghorn via SWNS

The secret behind T. rex's bone-crushing bite was its slitty 'keyhole' like eyes, according to new research.

Unusual oval-shaped sockets enabled its skull to absorb the impact as dagger-like teeth chomped down - with a force of over seven tons.

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

How it managed to snap an armored Triceratops or unfortunate Edmontosaurus in half without breaking its jaw has baffled paleontologists for decades.

Now British scientists have come up with the answer - by analyzing the eye sockets of around 500 different dinosaurs and related species, such as crocodiles.

They found big predators, like T. rex, evolved different shaped eyes to better deal with high bite forces as they pounced on prey.

In many animals, including most dinosaurs, the socket is just a circular hole in the skull housing the eyeball. But this is not the case in large carnivores.

Dr. Stephan Lautenschlager, of the University of Birmingham, said: "The results show only some dinosaurs had eye sockets that were elliptical or keyhole-shaped.

"However, all of those were large, carnivorous dinosaurs with skull lengths of a metre (3ft 3in) or more.

"Dinosaurs evolved different eye socket shapes to allow stronger bites. They were all the better to better eat you with," he quipped.

Dr. Lautenschlager tested their purpose by using computer simulations and stress analysis.

Results demonstrated a skull with a circular eye socket was more prone to stress during biting.

Replacing them with other shapes considerably reduced them - enabling T. rex to develop its notorious weapon without compromising skull stability.

Dr. Lautenschlager said: "Evolving narrower eye sockets than their ancestors may have helped T. rex and similar large carnivorous dinosaurs - known as theropods - to bite more powerfully."

The study also analyzed the maximum eyeball sizes that could be accommodated by Tyrannosaurus model skulls with either a circular or keyhole-shaped socket.

Dr. Lautenschlager said: "Keyhole-shaped eye sockets deformed less during biting compared to circular sockets, and helped to reduce the stress that skulls were subjected to by distributing forces along stronger parts of the skull behind the eye socket.

"However, the Tyrannosaurus model with a circular eye socket could accommodate an eyeball with a volume seven times larger than the model with the keyhole-shaped socket."

The study also showed plant-eating dinosaurs and juveniles retained a circular socket.
Only large meat eaters adopted elliptical, keyhole or figure-of-eight-shaped ones.

Dr. Lautenschlager said: "They tended to have circular sockets as juveniles. More ancient species tended to have more circular eye sockets than more recent species, with large theropods having more keyhole-shaped eye sockets than their ancestors.

"These observations suggest that larger carnivorous species evolved keyhole-shaped eye sockets over time but that they developed this shape as adults, not juveniles."

He added: "In these species, just the upper part of the eye socket was actually occupied by the eyeball. This also led to a relative reduction of eye compared with skull size."

T. rex lived 69 to 66 million years ago - at the end of the age of the dinosaurs. Its earliest ancestor dates back 230 million years.

It was killed off, with all the others, when a giant space rock smashed into the Gulf of Mexico.

Dr. Lautenschlager said: "Evolving narrower eye sockets may have reduced the space available for eyeballs within theropod skulls while increasing the space available for jaw muscles and enhancing the robustness of their skulls.

"This may have helped them bite more powerfully at the expense of accommodating larger eyes, which previous research has proposed can improve visual perception. The findings highlight the functional trade-offs that have shaped dinosaur evolution."

T. rex was one of the biggest land predators to roam Earth. It reached 40 feet long, 12 feet tall and weighed over eight tons.

The findings in the journal Communications Biology settle 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 adaptation.

Dr. Lautenschlager also investigated what would have happened if the eyes had increased in size at the same rate as the head.

They would have been almost a foot (30cm) in diameter and weighed nearly 44lbs (20kg) - instead of an estimated five inches (13cm) and 4.4lbs (2kg).

Previous research has found T. rex had 'binocular vision' - allowing it to see three-dimensional objects more clearly. It had better eyesight than humans - and even hawks.

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