The tooth-whorled, circle-saw-tooth shark

Helicoprion is a genus of extinct, shark-like eugeneodontid holocephalid fish. Almost all fossil specimens are of spirally arranged clusters of the individuals’ teeth, called “tooth whorls”. The tooth-whorls look like circle saws. It is surely one of the most unique looking fish that has ever lived.

Family: †Helicoprionidae

Genus: †Helicoprion

Species: †bessonowi 


Phylum– Chordata

Class– Chondrichthyles

Order– Eugeneodontida

Family– †Helicoprionidae            

Genus– †Helicoprion

Species– †bessonowi

Status: EXTINCT. Helicoprion lived in the oceans of the early Permian period, 290 million years ago. Cisuralian-Guadalupian

Average Size and Length: Based on a fossilized whorl found in 2011, it is estimated that Helicoprion could be between 33 and 39 feet long. But typically, 13-25 feet in length.

Average Weight: Some research suggests between 500 and 1000 pounds.

Current Rare Mythical Sightings: Helicoprion is just as mystical and enchanting today, and still holds our interest and wonder. This is a frequent shark that is featured on Shark Week, and River Monsters.

Teeth and Jaw: The most distinctive feature of Helicoprion (also, the only collected fossilized specimen until 2013) are their teeth, which is arranged in what is known as a “tooth-whorl”, which looks like a circular saw. What a sight this shark must have been. In early fossil collection, paleontologists thought that the tooth-whorl was a part of the upper-jaw, but today it is now known to be a part of the lower-jaw. Essentially, it is a growth ring of teeth, pushing out the old teeth allowing new ones to be exposed. Scientists in the past thought that the whorl was in the front part of the jaw, then in the throat, but now scientists believe it was in the back of the jaw.

Scientists suggests that the top jaw was absent of teeth, allowing it to be leverage for the bottom jaw to use its teeth to crush against.

In Idaho, in 2011, a fossilized whorl was found that measured 18 inches long. Back in the 30’s another whorl had about 32 teeth in the first round, 36 in the second and 41 in the last. The teeth are about 7mm long, 2.4 inches wide reaching 1.6 inches long and 9.5 inches wide. They are symmetrical (J. H. Menke, 1931).

Head: Helicoprion had a long and very narrow skull, creating a long nose similar to the modern-day Goblin shark.

Demographic, Distribution, Habitat, Environment and Range: North America, Eastern Europe, Asia, and Australia. More than 50% of Helicoprion specimens are known from Idaho, with an additional 25% being found in the Ural Mountains. Research suggests that due to the fossils’ locations, the various species of Helicoprion may have lived off the southwestern coast of Gondwana, and later, Pangaea.

Diet: According to Tapanila and team in 2013, Helicoprion likely ate soft-tissue prey such as squid.

Aesthetic Identification: There is a lot of speculation as to what Helicoprion really looked like. Most of the focus has been on the tooth whorl. But it is said to look shark-like, but is most closely related to what are known as ratfish and chimeras.

Biology and Reproduction: Scientists are still researching and speculating about this.

Behavioral Traits, Sensing and Intelligence: Scientists can only speculate. Little is known.


2013 Idaho State University: “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,” said Leif Tapanila, principal investigator of the study, who is an ISU Associate Professor of Geosciences and Idaho Museum of Natural History division head and research curator. According to 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 joint of the jaw. We were able to refute that it might have been located at the front of the jaw.”

Tapanila notes: “Another major find was that this famous fish, presumed to be a shark, is more closely related to ratfish, than sharks”.

The results of the study, “Jaws for a spiral tooth-whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion,” are being published in the Royal Society’s journal, Biology Letters.

Speed:  Scientists are still speculating.