Scientists have discovered the unique internal structure of the serrated teeth belonging to carnivorous dinosaurs like T. rex and Allosaurus.
This structure allowed them to rip through flesh and bones of larger animals, surviving as top predators for around 165 million years.
The research, published in Scientific Reports, used microscopes to examine and analyse tooth slices.
It revealed a crucial layered arrangement of tissue inside the teeth.
Like a steak knife, dinosaur teeth have serrated edges designed to slice through meat.
Teeth are made of tough tissue called dentine, surrounded by an outer coating of enamel.
The researchers discovered a special arrangement of layers of dentine at the base of each serration in the tooth.
"This helped to enlarge the serration on the inside the tooth," said Kirstin Brink, a post-doctoral researcher at the University of Toronto Mississauga.
"It also helped to strengthen it and prevented it from wearing away too quickly while the animal was eating."
Unlike humans, dinosaurs could grow new teeth to replace lost ones. But this could take up to two years. Having an internal structure that protected the tooth meant these animals had a stronger and better bite.
The team also examined "unerupted" teeth, which had not yet broken through the gums. Their structure was similar to older teeth, showing that it did not develop as a response to the dinosaurs chewing hard materials.
"In general, meat-eating animals have less complex teeth than plant eaters as plant matter has to be chewed and ground up. It was surprising to find that theropods, which eat meat, had this complexity," Dr Brink told the BBC.
The dinosaur teeth in the study ranged from 3-20cm in length, and were obtained from museum collections.
Commenting on the study, Prof Paul Barrett from the Natural History Museum in London told BBC News: "This topic has not previously been examined with this level of detail. It shows how, at a microscopic level, the teeth are adapted for their job."