Despite having sat beneath our feet for some 65 million years, dinosaur fossils continue to lead to new discoveries on a regular basis. For instance, rather than looking like the “terrible lizard” that gives it its name, we only recently learned that Tyrannosaurus rex looked more like a goofy tropical bird adorned with feathers. Now, a new study by researchers at the University of Toronto Mississauga have made another discovery – the secret that gave T. rex it’s powerful bite.
Fossilized teeth belonging to theropods, which include T. rex and velociraptor, share some common traits. They’re serrated, which isn’t that surprising for a carnivorous animal. What is surprising, though, is that every theropod tooth specimen seemed to have numerous hairline cracks. For years, scientists assumed these were signs of damage from tough meals. As it turns out, they were the exact opposite.
“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,” said Kirstin Brink, a post-doctoral researcher in the Department of Biology at UTM. “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.”
Rather than stress fractures, the small cracks are actually deep folds stemming from each serration, and they actually strengthen the tooth. An examination of juvenile teeth (which had not yet breached the gum-line and thus had not been used) confirmed this – the strengthening folds developed in the teeth intentionally.
Digging further, slicing into the teeth yielded more discoveries. It turns out that theropods had an extra layer of calcified tissue known as dentin below their enamel, further strengthening the teeth from damage. The only land animals today that have serrated teeth structures are komodo dragons, but they lack the tiny folds and extra dentin.
The scientists believe that the unique features were purely functional – T. rex preyed on animals as larger (or larger) than themselves, necessitating teeth that could both withstand pressure from a struggling animal and cut through tough flesh.