Predators like T. Rex adapted their eye sockets to their bite

Aug. 12 () –

Large predatory dinosaurs, such as Tyrannosaurus rex, evolved different shapes of eye sockets to better deal with high bite forcesshows new research.

While in many animals, and most dinosaurs, the eye socket is just a circular hole in the skull that houses the eyeball, this is very different in large carnivores.

In a new study, published in Communications Biologyresearchers at the University of Birmingham reveal how unusually elliptical or oval eye sockets found in the skulls of these predators could have evolved to help the skull absorb shock when they lunged at their prey.

Dr Stephan Lautenschlager, Senior Lecturer in Palaeobiology at the University of Birmingham and author of the new study, analyzed the shape of the eye sockets of some 500 different dinosaurs and related species.

“The results show that only some dinosaurs had elliptical or keyhole-shaped eye sockets,” he said. “However, these were all large carnivorous dinosaurs with skulls a meter or more in length.”

Using computer simulations and stress analysis, Lautenschlager tested what purpose these unusual eye socket shapes might serve. The results showed that a skull with a circular eye socket was more prone to high stress during bite. However, if these were replaced with other forms of eye sockets, the stresses were greatly reduced, allowing top predators, including Tyrannosaurus rex, to develop high bite forces without compromising skull stability.

The study also showed that most plant-eating species and juvenile individuals retained a circular eye orbit. Only large carnivores adopted other morphologies, such as elliptical eye sockets, in the form of a keyhole or in the form of a figure of eight.

Lautenschlager added: “In these species, only the upper part of the eye socket was occupied by the eyeball. This also led to a relative reduction in eye size compared to skull size.”

The researchers also investigated what would have happened if the size of the eyes had increased at the same rate as the length of the skull. In such a case, the eyes of Tyrannosaurus rex would have been up to 30 cm in diameter and weighing almost 20 kg (instead of the estimated 13 cm and 2 kg).