Tyrannosaurus rex and other theropod dinosaurs were fearsome predators thanks to a unique, deeply serrated tooth structure that helped them easily tear through the flesh and bone of bigger animals.
The only reptile living today with something similar is the Komodo dragon—which also preys on larger animals.
For a new study, researchers determined that this sawlike tooth structure is uniquely common to carnivorous theropods such as T. rex and Allosaurus, and even one of the first theropods, Coelophysis.
While other extinct animals had teeth that were superficially similar, it was the special arrangement of tissues inside the tooth that strengthened and improved the function of T. rex teeth. The deep serrations made them much more efficient at chomping on bones and ripping flesh of larger animals and reptiles, and allowed them to prosper for about 165 million years.
“What is so fascinating to me is that all animal teeth are made from the same building blocks, but the way the blocks fit together to form the structure of the tooth greatly affects how that animal processes food,” says Kristin Brink, a postdoctoral researcher in the biology department at the University of Toronto Mississauga.
“The hidden complexity of the tooth structure in theropods suggests that they were more efficient at handling prey than previously thought, likely contributing to their success.”
Slices of teeth
The researchers also discovered that the unique arrangement of tooth tissues didn’t develop in response to these carnivores chewing hard materials. They determined this by examining samples of dinosaur teeth that had not yet broken through the gums, as well as samples from mature dinosaur teeth. Unlike humans, reptiles grow new teeth throughout their lifetime.
“What is startling and amazing about this work is that Kirstin was able to take teeth with these steak knife-like serrations and find a way to make cuts to obtain sections along the cutting edge of these teeth,” says Robert Reisz, professor of biology.
“If you don’t cut them right, you don’t get the information. This brought about a developmental explanation for the tooth formation; the serrations are even more spectacular and permanent.”
For the study published in the journal Scientific Reports, researchers used a scanning electron microscope and a synchrotron—a microscope that allows the user to understand a substance’s chemical composition—to do a thorough examination and analysis of tooth slices from eight carnivorous theropods, including T. rex, Allosaurus, Coelophysis, and Gorgosaurus.
The samples came from various museums, including the ROM, the Canadian Museum of Nature in Ottawa, and the Royal Tyrrell Museum in Alberta.
Source: Elaine Smith for University of Toronto