Armour Plated Fish
(Dunkleosteus ferrelli)

Dunkleosteus might have been the owner of the most powerfull jaws in the whole history of life. This creature was an armour plated fish that could be up to 9 meters (30 feet) long. The family of armour plated fish (The Placondermi) envolved in the early Devonian and died out in the early Carbonian, there are no relatives alive today.
The jaws of Dunkleosteus where used for slicing trough armour plates of other fish, it lacked true teeth, instead it had two long bony blades that could snap and crush almost anything. Dunkleosteus ate fuhrtermore sharks, who just appeared at that time, and it was a cannibal as well. It seems that Dunkleosteus suffered from indigestion as a result: its fossils are often associated with regurgitated, semi-digested remains of fish.