The Tyrannosaurus Rex is known for being one of the most fearsome creatures to ever walk the Earth, and new research suggests the beast could open its jaws at a terrifying 90-degree angle. The findings could provide valuable insight into the eating habits of ancient dinosaurs.

Using digital models and a computer analysis, a team of researchers looked at the muscle strain during jaw opening of three different theropod dinosaurs with a variety of dietary habits, the University of Bristol reported.

"Theropod dinosaurs, such as Tyrannosaurus rex or Allosaurus, are often depicted with widely-opened jaws, presumably to emphasise their carnivorous nature.  Yet, up to now, no studies have actually focused on the relation between jaw musculature, feeding style and the maximal possible jaw gape," said Stephan Lautenschlager from Bristol's School of Earth Sciences.

The study included the carnivorous T. rex, the smaller but also carnivorous Allosaurus fragilis, and the plant-eating Erlikosaurus andrewsi.

"All muscles, including those used for closing and opening the jaw, can only stretch a certain amount before they tear.  This considerably limits how wide an animal can open its jaws and therefore how and on what it can feed," Lautenschlager said.

The study found the Tyrannosaurus and Allosaurus could open their jaws at a 90-degree angle, while the herbivorous Erlikosaurus could only open their jaws at an angle of about 45 degrees. The computer simulations also showed the T. rex could bite at a variety of angles perfect for tearing through flesh and bones.

"We know from living animals that carnivores are usually capable of larger jaw gapes than herbivores, and it is interesting to see that this also appears to be the case in theropod dinosaurs," Lautenschlager concluded.

The findings were published in a recent edition of the journal Royal Society Open Science.