Helicoprion was a helicoprionid eugenodontid fish from the Cisuralian-Guadalupian of Russia, the United States of America, China, Canada, Australia, Mexico, Kazakhstan, and Japan. It was named in 1899 by Alexander Karpinsky. It was a strange eugenodontid notable for its tooth whorl (embedded in its lower jaw), which caused lots of confusion as to how it lived.
Physiology[]
Helicoprion resembled a shark, with a torpedo-shaped body, triangular pectoral and dorsal fins, a crescent-shaped caudal fin, a mid-sized head with a pointy, conical nose and large jaws. However, it had one major defining characteristic: its curved jaws had only one linear row of teeth; as well as this, its lower jaw was more curved than its upper jaw, which gave it the appearance of a buzz-saw. Its body would have been covered in scaly skin.
Diet[]
Helicoprion was a predator, preying on soft-bodied cephalopods. Its tooth whorl had teeth designed for getting a hold of prey, as well as slicing their flesh.
Ecology[]
For a while, it was unknown what Helicoprion's tooth whorl looked like, and many early reconstructions depicted it as a prehensile lash as well as a circular saw situated on the tip of a long lower jaw; however, recent studies (involving the most recent fossil and a CT scanner) have revealed that the whorl would have been situated directly in the lower jaw. As well as this, people did not know how it used said tooth whorl to feed, first depicting it as a lash against fish before considering it to be used as a saw for cutting through the shells of ammonites; once again, these hypotheses have been disproved, as a look at the fossil whorl confirms that the teeth didn't wear. Combined with the fact that it didn't replace worn teeth, it now causes people to speculate that Helicoprion was a specialized predator of soft-bodied mollusks, specifically cephalopods; in order to feed, Helicoprion would swim towards a prey item and open its mouth wide before biting down on it, and would proceed to open and close its mouth in a smaller angle in order to push prey further into its mouth. To add onto this, the teeth on its whorl served different functions; the front teeth snagged prey and pulled it further into its mouth, while the middle and back teeth punctured its meal and pushed it into its throat.
In popular culture[]
Helicoprion was featured in a special episode of the documentary River Monsters, appearing alongside Xenacanthus, Xiphactinus, Leedsichthys, Megapiranha, Dunkleosteus, and Rhizodus as candidates for the most terrifying prehistoric river dweller. During this episode, Jeremy Wade, the scientist behind the show, researches how its tooth whorl functioned and what it ate; after a while, he rules it off its list due to its non-crushing bite.