Majungasaurus

Majungasaurus grew new teeth about every two months.

Talk about high turnover. A meat-eating dinosaur species that lived in Madagascar some 70 million years ago replaced all its teeth every couple of months or so, a new study has found, surprising even the researchers.

In fact, Majungasaurus grew new teeth roughly two to 13 times faster than those of other carnivorous dinosaurs, says Michael D. D’Emic, an assistant professor of biology at Adelphi University. Majungasaurus would form a new tooth in each socket every couple of months.

“This meant they were wearing down their teeth quickly, possibly because they were gnawing on bones,” D’Emic says. “There is independent evidence for this in the form of scratches and gouges that match the spacing and size of their teeth on a variety of bones — bones from animals that would have been their prey.”

Some animals today, too, will gnaw on bones, including rodents, D’Emic explains. It’s a way for them to ingest certain nutrients. It also requires exceptionally strong teeth — but Majungasaurus did not have those.

“That’s our working hypothesis for why they had such elevated rates of replacement,” D’Emic says. The rapid-fire tooth growth puts Majungasaurus in same league with sharks and big, herbivorous dinosaurs, he adds.

Although at least a few hundred meat-eating dinosaur species roamed the Earth, researchers have analyzed tooth-replacement rates for only about a half-dozen of them, D’Emic says. He also has looked into tooth-replacement patterns in plant-eating dinosaurs.

“I’m hoping this latest project spurs more people to study other species. I bet that will reveal further surprises,” he says. “And hopefully that will lead to a better understanding of how dinosaurs evolved to be successful for so long.”

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