Ancient Helicoprion Ratfish Had Spiral-Toothed Jaw

Posted on February 27, 2013

The ancient Helicoprion had a bizarre spiral-toothed jaw. The fish was initially thought to be a species of shark, but researchers at Idaho State University have determined that Helicoprion was a type of ratfish. They also determined where the buzz-saw like teeth fit in the creature's mouth. The saw-like teeth were located in the back of Helicoprion's jaw. The scientists say the jaw created a rolling-back and slicing mechanism. The researchers believe Helicoprion - which grew as long as 25-feet - ate soft-tissued prey such as squid, rather than hunting hard-shelled animals.

Leif Tapanila, principal investigator of the study, says in the announcement, "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 joint of the jaw. We were able to refute that it might have been located at the front of the jaw."

Tapanila also said, "It was always assumed that the Helicoprion was a shark, 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."

The study, "Jaws for a spiral-tooth whorl," was published here in the Royal Society journal Biology Letters.