Dunkleosteus were real!  The Dunkleosteus was one of the fiercest fish alive during the Late Devonian period, 360-370 million years ago. Fossils have been found in North America. They were 30 feet long and could weigh up to 8000 lbs, which makes it one of the largest placoderms that ever lived. The Dunkleosteus had a big, powerful build and an immense bite force that could chop prehistoric fish easily.  They did not have teeth, instead they had two pairs of sharp bony plates that formed a beak-like structure that could eat and bend hard materials easily. With a bite force around 6000 lbs, it could easily bite through your fishing boat!