Helicoprion, whorl-tooth shark Protoceratops 2A Orohippus forefoot

2A Orohippus forefoot

the largest example of Machairodus

and a long

The serial growth forms

13---therizinosaurus claw 23 inch

Helicoprion, whorl-tooth shark Protoceratops 2A Orohippus forefootHelicoprion ("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