Helicoprion

Tooth spiral of Helicoprion

• Russia
• North America (Canada, USA, Mexico)
• Japan
• Australia

Helicoprion is an extinct genus of fish cartilage from the lower and middle Permian. Apart from the fossil preserved rolled tooth spirals of fish no further fossils are known.

Features

The discovered fossil teeth tightly together, laterally strongly flattened spiral that could have in adult animals more than three whorls and consisted of up to 180 teeth. About the function and the position of the tooth spiral prevailed for a long time unclear. Most of them were located at the tip of the lower jaw, rarely on the upper jaw tip to the dorsal fin, similar to the dentate, anvil -shaped dorsal fins of male Stethacanthus or on the tail fin. It has been speculated that this is a case of Peckhamscher mimicry and the tooth spiral should attract ammonites, which were then eaten, or that she was a special teeth for biting of shells. It could also have served to make schooling fish by violently back and Herschlagen immobilize or kill, similar to the extant sawfish ( Pristiformes ) use their saw.

Computed tomography scans of the single - Helicoprion Fossils, which in addition to a tooth spiral even more skeletal elements, show that the tooth spiral occupied the entire length of the lower jaw and the grinding was their prey.

In reconstructions of the fish are usually depicted with a shark-like body. The body length is estimated to be more than a meter.

System

Systematically Helicoprion one of the Eugeneodontiformes, a cartilaginous fish group with similar dentition. The Eugeneodontiformes turn belong to the Paraselachimorpha, a potentially with recent chimaeras ( Chimaeriformes ) distantly related group, which had, in contrast to these but haiähnliche teeth were continually replaced.