Helicoprion ("Spiral Saw") was a long-lived genus of shark-like cartilaginous fish that first arose in the oceans of the late Carboniferous 80, survived the Permian-Triassic Extinction Event, and eventually went extinct during the early Triassic some 25 .
The individual teeth are serrated, and it is implied that Helicoprion was carnivorous. As there has yet to be an actual skull found, exactly how it captured or fed on its prey are subjected to a great deal of speculation. One hypothesis that it preyed on ammonites and that the teeth were specialized for the job of breaking into the ammonites' shells. Another idea was that the shark would swim into a school of fish and fling out the jaw, snagging prey on its many teeth. Notable specimens of Helicoprion have been found in eastern Idaho, northern Utah, and the far central western part of Wyoming.