Helicoprion, whorl-tooth shark Protoceratops the largest example of Machairodus

the largest example of Machairodus

The Messel quarry

while some of the smaller species existed until about 4

The serial growth forms

and a long

Helicoprion, whorl-tooth shark Protoceratops the largest example of MachairodusHelicoprion ("Spiral Saw") was a long lived genus of shark like cartilaginous fish that first arose in the oceans of the late Carboniferous 280 million years ago, survived the Permian Triassic Extinction Event, and eventually went extinct during the early Triassic some 225 million years ago. The only fossils known are the teeth, which were arranged in a fantastic "tooth whorl" strongly reminiscent of a circular saw. It was not until the discovery of