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Serrated teeth: secret weapon of T. Rex

Serrated teeth: secret weapon of T. Rex - The researchers have uncovered secret structures hidden within the notched teeth of Tyrannosaurus rex and other theropods that helped the dinosaurs tear apart their prey without chipping their pearly whites.

The researchers examined the teeth of theropods - a group of bipedal carnivorous dinosaurs that includes T. rex and Velociraptor - to study the mysterious structures that appeared like cracks within each tooth.

Study lead researcher Kirstin Brink, a postdoctoral researcher of biology at the University of Toronto Mississauga, said these structures were not cracks, but deep folds within the tooth that strengthened each individual serration and helped prevent breakage when the dinosaur pierced through its prey.

The study started with a Dimetrodon, a Paleozoic animal with serrated teeth that lived before the dinosaurs. When Brink sliced the Dimetrodon tooth in half and compared it with the serrated teeth of dinosaurs, she found they had different internal structures.

Brink said they look similar on the outside but it's only when you cut them open you will see that they are completely different.

Brink obtained 2-3 teeth from 8 different theropods species, including T. rex, Carcharodontosaurus saharicus and Coelophysis bauri. She also looked at the specimens of theropod teeth that had not fully matured and erupted past the gum line, meaning they had not been used for feeding.

Using a scanning electron microscope and a synchrotron (a microscope that helps determine the chemical composition of a substance), it was found that each tooth, even the ones that had not yet erupted, had these cracklike structures next to each serration. This demystified the idea that the cracks were artifacts of eating a meaty meal, Brink said.

Each structure has a few additional layers of calcified tissue, called dentine, under the tooth's outer enamel coating, making it hard and tough.

Serrated teeth assist animals in piercing flesh and hold onto chunks of meat. The formations, which the researchers call "deep interdental folds," strengthen the serrations.

The study has been published online in the journal Scientific Reports.