Paleontologists made an interesting discovery this week as they found the fossil of a meat-eating dinosaur that has the ability to replace all its teeth in 56 days. This might not be a big feat, but for a reptile that existed more than 70 million years ago, this is a huge deal.
WHAT'S SO SPECIAL ABOUT THE MAJUNGASAURUS?
The dinosaur, which was named Majungasaurus, was first discovered by a French paleontologist named Charles Deperet after the place where it was unearthed -- the Mahajanga province in northwest Madagascar.
Although there are a lot of studies made about this particular dinosaur and other similar species, it was only recently that scientists were able to discover that the Majungasaurus can replace a toothless than a month. This phenomenon of changing teeth is most commonly observed in herbivores; however, the Majungasaurus is not a herbivore. In an interview with Newsweek, Michael D. D'Emic, an assistant professor of biology at Adelphi University and the study's lead author explains, "this meant that the Majungasaurus were wearing down on their teeth quickly, possibly because they were gnawing on bones. 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 of animals that would have been their prey.
For this study, D'Emic worked with Patrick O'Connor, a professor of anatomy from Ohio University, and together, they examined a collection of fossil teeth and looked for microscopic growth lines. These growth lines are similar to a tree's annual ring that leaves a mark every time growth occurs, but unlike a tree's that happen once a year, the growth lines on the fossilized teeth occur every day. The findings are published in PLOS ONE.
The researchers then used computerized tomography on the fossilized jaw of Majungasaurus to be able to see how the teeth grew inside the bone. The two sets of data that were taken together enabled the estimation of the rate of tooth replacement. The researchers used several jawbones for the cross-checking of the results.
D'Emic and his team compared Majungasaurus teeth to their relatives, specifically Allosaurus and Ceratosaurus. They performed the same analysis to the related theropods, and the results showed that the ability to change its teeth rapidly is unique among Majungasaurus. Sometimes, the growth rate of these teeth varies from roughly 56 days to 104 and 107 per tooth. Scientists believe that this phenomenon is an adaptation meant to secure access to certain nutrients that are scarce during those times or relatively hard to acquire, a behavior similar to rodents and their hypsodonts.
The scientists behind the discovery also noted how Majungasaurus did not have exceptionally strong teeth. It has soft teeth that would get worn out every after eating. This explains why it needs to regrow them often, to sustain this behavior.
The team also compared the Majungasaurus teeth to that of top predator Tyrannosaurus rex. According to the researchers, the T. rex was able to evolve robust teeth with slow replacement rates that helped it feed.
