Jaws

It's one of the most important developments in the history of life. An adaptation that lets animals kill, butcher, and devour. There is perhaps no instrument more important to survival than a strong set of jaws. From the shark's rows of razor-sharp serrated teeth, the crocodile's overwhelmingly swift-snapping-trap, to the lion's shredding canines--all have evolved in response to the never-ending struggle between predator and prey. But just how did these ultimate killing weapons develop in the first place?