At the University of Bristol, researchers have now revealed that the feeding style and dietary preferences of dinosaurs were closely linked to how wide they could open their jaws.
Using digital models and computer analyses, Dr Stephan Lautenschlager studied the muscle strain during jaw opening of three different theropod dinosaurs with different dietary habits.
Theropods were a diverse group of two-legged dinosaurs that included the largest carnivores ever to walk the Earth.
The research looked at T rex, a large sized meat-eating theropod with a massively built skull and up to 15 cm long teeth and two other predatory and meat-eating theropods.
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," the researchers noted.
The results found that the carnivorous Tyrannosaurus and Allosaurus were capable of a wide gape (up to 90 degrees) while the herbivorous Erlikosaurus was limited to a small gape (around 45 degrees).
Between the two carnivores, Tyrannosaurus could produce a sustained muscle (and, therefore, bite) force for a wide range of jaw angles, which would be necessary for biting through meat and skin and crushing bone.
"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," Dr Lautenschlager concluded.
The research was published in the journal Royal Society Open Science.