Prehistoric Monster Shark Had Chainsaw Teeth

Scientists have revealed a 25-foot "monster shark" with teeth that functioned like a chainsaw.

Named the Helicoprion, the creature was an early ancestor of sharks and existed about 270 million years ago. Scientists claim the Helicoprion had a set of teeth that basically functioned as a conveyor belt, allowing them to spiral out and tear apart its prey. Its length and weight of half a ton made it the largest fish in the ocean. Scientists confirmed the find by analyzing fossils of the teeth, which are basically all that remain of the creature, since its skeleton was made of cartilage.

The new findings were revealed by researchers at Idaho State University, whose Museum of Natural History boasts the world's largest collection of Helicoprion spiral-teeth fossils. A problem for the researchers, however, has been their inability to determine exactly how the unique set of teeth fit into the fish's mouth, largely because of their inability to examine its fossil record. They have now solved this problem with CAT scans and 3-D virtual reconstruction technology.

"New CT scans of a unique specimen from Idaho show the spiral of teeth within the jaws of the animal, giving new information on what the animal looked like, how it ate," says principal investigator and ISU Associate Professor of Geosciences Leif Tapanila. "We were able to answer where the set of teeth fit in the animal. They fit in the back of the mouth, right next to the back point of the jaw. We were able to refute that it might have been located at the front of the jaw."

The scientists also found that the Helicoprion shares a closer relation to ratfish than sharks, which are classified separately.

"It was always assumed that the Helicoprion was a shark," Tapanila says, "but it is more closely related to ratfish, a Holocephalan. The main thing it has in common with sharks is the structure of its teeth, everything else is Holocephalan."

In wake of the developments, the Idaho Museum of National History will display a replica of a 13-foot long Helicoprion at an exhibition this summer. The exhibit will also feature artwork by acclaimed science illustrator Ray Troll.

The new findings are published in the Royal Society journal Biology Letters.