Tyrannosaurus rex was a vicious creature, capable of delivering killing blows while engaged in battle. Now, researchers have found the ancient animals possessed powerful tools that helped them win the deadly engagements. 

Serrated teeth could have assisted Tyrannosaurus rex and other theropods to tear into the bodies of their opponents, researchers speculate. Such a design would have also likely reduced possible damage to the teeth of the dinosaurs. 

Theropods are a group of bipedal dinosaurs that include both Tyrannosaurus rex and the speedy, intelligent velociraptors. Researchers examined features in the teeth that resembled tiny cracks. The team discovered that, instead of being cracks, these structures were folds within the teeth that strengthened individual serrations, reducing the chance they would break during deadly encounters. The crack-like features were discovered two decades ago in Albertosaurus, a relative of T. rex. Initial analysis of those ancient remains suggested the structures were cracks, likely produced during hunting or battles over territories and mates. 

"I sectioned teeth from eight other theropods besides Albertosaurus, and found that the structure is actually in all theropods, and it's not actually a crack," Kirstin Brink, a postdoctoral researcher in the biology department of the University of Toronto Mississauga, said. 

This new study of theropods started with an ancient animal often confused with dinosaurs, known as Dimetrodons. However, those ancient creatures lived well before the age of the "terrible lizards." After slicing Dimetrodon teeth in half, the researchers discovered the structures were far different than the design of serrated teeth in theropods, a fact not obvious from external observation. 

"They look very similar on the outside. It's only when you cut them open [that you see] that they're completely different," Brink stated in a press release on the discovery. 

Intrigued by the discovery, Brink obtained additional theropod teeth, including specimens of T. rex, Carcharodontosaurus saharicus and Coelophysis bauri. Some of the samples in the investigation were so immature, they never erupted from the gum line. This means they were never used for fighting or chewing. Even these unused teeth were shown to have identical folds to the mature specimens, thereby contradicting the earlier idea that the features seen in the teeth were cracks. 

Teeth of sauropods were also found to be further protected by a coating of a few layers of dentine, a form of calcified tissue, under the outer coating of enamel. Today, Komodo dragons possess serrated teeth, but these lack interdental folds and dentine, researchers stated. 

Theropods ruled as successful hunters at the top of the food chain for 165 million years, and the unique designs of the teeth may have played a critical role in shaping their success. 

Analysis of theropod teeth was published in the journal Scientific Reports. 

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