Bizarre, Prehistoric Ratfish Chomped Prey with Buzzsaw Jaws

A restoration of Helicoprion by artist Gary Staab, showing off the prominent tooth whorl.

Helicoprion had saws for jaws. That’s really all there was to the 270 million year old ratfish’s dental cutlery. No upper teeth or anything else to slice against – just an ever-growing whorl of spiky teeth anchored to the lower jaw.

This new, definitive image of Helicoprion debuted last year thanks to the efforts of artist Ray Troll and a team of researchers led by Idaho State University paleontologist Leif Tapanila. A very special fossil – IMNH 37899 – preserved both the upper and lower jaws in a closed position, finally solving the mystery of what the ratfish’s head actually looked like. But determining the exact placement of that vexing spiral was just an initial step.

Paleontologists and artists had often supposed that Helicoprion had upper teeth to pierce slippery cephalopods and squirming fish, but the fossils Tapanila and colleagues examined showed that Helicoprion only had a buzzsaw embedded in the lower jaw. How did this long-lived and prolific genus of Permian fish eat with a saw for a jaw?

Part of the original Helicoprion project involved creating a virtual model of the fish’s skull from CT scans of IMNH 37899. Now, in a Journal of Morphology paper, University of Rhode Island biologist Jason Ramsay and the rest of the team from last year’s Helicoprion study have gone back to those models to outline how the freaky ratfish fed.

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http://phenomena.nationalgeographic.com/2014/09/03/bizarre-prehistoric-ratfish-chomped-prey-with-buzzsaw-jaws/