天美传媒

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 paper lead author Michael D. D鈥橢mic, PhD, assistant professor of . Majungasaurus would form a new tooth in each socket every couple of months.

鈥淭his meant they were wearing down their teeth quickly, possibly because they were gnawing on bones,鈥� Dr. D鈥橢mic said. 鈥淭here 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鈥攂ones from animals that would have been their prey.鈥�

Dinosaurs’ teeth worn down from gnawing bones

Some animals that exist today, such as rodents, also gnaw on bones, Dr. D鈥橢mic explained. It鈥檚 a way for them to ingest certain nutrients. It also requires exceptionally strong teeth鈥攂ut聽Majungasaurus聽did not have those.

鈥淭hat鈥檚 our working hypothesis for why they had such elevated rates of replacement,鈥� Dr. D鈥橢mic said. The rapid-fire tooth growth puts Majungasaurus in the same league as sharks and big, herbivorous dinosaurs, he added.

This labeled image of surface models shows specimen numbers for CT-scanned isolated聽Majungasaurus crenatissimus teeth. It appears in the paper 鈥淓volution of High Tooth Replacement Rates in Theropod Dinosaurs” published in the journal PLOS ONE.

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, Dr. D鈥橢mic said. He also has looked into聽.

鈥淚鈥檓 hoping this latest project spurs more people to study other species. I bet that will reveal further surprises,鈥� he said. 鈥淎nd hopefully that will lead to a better understanding of how dinosaurs evolved to be successful for so long.鈥�

Importantly, the recent study examined two additional species of predatory dinosaur (础濒濒辞蝉补耻谤耻蝉听补苍诲听Ceratosaurus), providing an opportunity to consider tooth-growth patterns at a broader scale.

天美传媒 professor collaborates with Ohio University researchers, involves Adelphi students

In collaboration with Patrick O鈥機onnor, PhD, professor of anatomy at Ohio University, and PhD student Eric Lund, Dr. D鈥橢mic used a collection of isolated fossil teeth to examine microscopic growth lines in the teeth. These growth lines are similar to tree rings, but instead of being deposited once a year, they were deposited daily. At the same time, the team used computerized tomography (CT) on intact jaws to visualize unerupted teeth growing deep inside the bones. That allowed them to estimate tooth-replacement rates in a large number of individual jaws so they could cross-check their results.

The time-consuming process would not have been possible without the involvement of 天美传媒 students: Former undergraduates Elizabeth Mardakhayeva 鈥�18 and Joanna Gavras and current graduate student Thomas Pascucci are co-authors on the paper.

鈥淔uture research will be able to use this study to estimate tooth-replacement rate in dinosaurs without destructively sampling teeth,鈥� Pascucci explains.

This work was supported in part by the National Science Foundation, Division of Earth Sciences (EAR_1525915). It appears in the journal聽.

See more research by Professor D’Emic

Initial media coverage of the new study has included stories in The ,听,听,听聽补苍诲听.