Dunkleosteus(pronounced dunk-leo-stee-uss) was the biggest predator. It was armour plated on the head, and instead of teeth it had giant plates of bone from its jaw that were just as dangerous, if not more so. The bone could cut through armour plating on other fish and slice through the inside of the fish with ease. Dunkleosteus ate just about anything that crossed its path,including other Dunkleosteus. Dunkleosteus had very bad table manners, as well - it would crack open the plating of a fish like it was a nut and eat the fish inside, then later it would spit out the plates and bones that were left behind. They had NO known predators as it was so big and powerful.