Animal IQ

This Ancient Shark Basically Had a Buzzsaw in Its Mouth

Sharks might not be as deadly as their reputation suggests, but they're still pretty much the last thing that we'd like to run into while taking a dip in the ocean. The only thing worse would be a prehistoric shark. They got downright freaky. Take Helicoprion, for example. If you encountered one back when they existed around 250 million years ago, you'd see the business end of a buzzsaw swimming straight for you.

An Impossible Smile

Consider the size alone, and you've already got a monster — estimates put Helicoprion at about 35 feet (11 meters) long. But when you look at it head-on, it becomes something out of a science-fiction movie. Instead of a set of interlocking chompers, it had a vertical wheel of teeth like a buzzsaw. 

It's hard to imagine how this shark used those teeth. After all, it's not as if the "buzzsaw" could have actually buzzed. Luckily, we're getting a better idea of how Helicoprion's bizarre mouth actually sliced into its prey. It didn't have any teeth on its upper jaw, leaving lots of room for the "saw" on the bottom row to swing up and in. Therefore, researchers think that it might have eaten by slicing apart soft-bodied prey like squids and octopuses as it swam through the water. Then, the backward motion of the lower jaw could push the newly bisected mollusks down the shark's throat.

An Endless Wheel of Death

You may have heard that modern sharks have multiple rows of teeth, with rows in back constantly pushing forward to replace the ones that have been lost in front. Helicoprion wouldn't have been much different. In fact, that might have been one of the primary features of the wheel — the ones at the very inside of the spiral of wheel would have slowly been pushing forward to replace the ones on the outside. So maybe the buzzsaw really did "buzz," just very, very slowly. Still, this is one monster we're glad we didn't share the planet with.

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Learn about more ancient beasts in "The Rise and Fall of the Dinosaurs: A New History of Their Lost World" by Steve Brusatte. The audiobook is free with an Audible trial. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Reuben Westmaas February 12, 2018

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