T.rex's serrated teeth tore through flesh

An artist's impression of Gorgosaurus, a cousin of T.rex, ripping apart another dinosaur with its serrated teeth (Danielle Dufault)

Will Dunham
Reuters

If you want to know the secret behind the success of Tyrannosaurus rex and its meat-eating dinosaur cousins, look no further than their teeth.
 
A comprehensive analysis of the teeth of the group of carnivorous dinosaurs called theropods, published in the journal Scientific Reports, details a unique serrated structure that let them chomp efficiently through the flesh and bones of large prey.

Theropods first appeared about 200 million years ago and were the dominant terrestrial meat-eaters until the age of non-avian dinosaurs ended about 65 million years ago.

The study involving eight theropod species revealed their previously unknown tooth complexity.
Internal dental tissues were arranged in a way that reinforced the strength and prolonged the life of teeth that were serrated like steak knives for easy dismembering of other dinosaurs.

Fossil evidence shows that T. rex's teeth could crush bone. Its teeth have been found embedded in the bones of its prey and chunks of bone appear in its fossilised dung, says the study's lead author palaeontologist Kirstin Brink of the University of Toronto Mississauga.

"But the serrations were most efficient for piercing flesh and gripping it while ripping off a chunk of meat, called the 'puncture and pull' feeding style," says Brink.

The researchers analysed slices from fossil teeth using a powerful microscope and a sophisticated device that revealed tooth chemical properties.

They studied teeth from: the early and relatively small Coelophysis; bird-like Troodon; large predators Allosaurus, Gorgosaurus, Daspletosaurus, Tyrannosaurus and Carcharodontosaurus; and big, semi-aquatic Spinosaurus.

The teeth of Tyrannosaurus and Carcharodontosaurus measured up to 23 centimetres long.
"In theropods, the serrations are larger and deeper than the superficial view suggests, making them stronger and longer lasting, less likely to get damaged or worn," says study co-author Professor Robert Reisz also of the University of Toronto Mississauga.

Dinosaurs were able to continuously grow teeth throughout their lives. When a tooth was broken, another could replace it.

"It could take up to two years for a tooth to grow back in the big theropods like T. rex. Therefore, having specially reinforced teeth means less tooth breakage and less gaps in the jaw, leading to more efficient eating," says Brink.

The Komodo dragon, an Indonesian lizard that grows up to three metres long, is the only living reptile with serrated teeth closely resembling those of theropods, although these teeth evolved independently of those of the dinosaurs, says Brink.