Dunkleosteus- The Giant Grindfish

Submission for the 2014 Creature Cabal
AND, the submission for national Fossil Day! In honor of this little-recieved day of the year, I present something from the fossil record, and is often regarded as the scariest thing in there.
This fish, which lived some 360 million years ago, lived in a time when armored fish were living in the seas. None of them now survive, but this was in the middle of their heyday. To combat the new, thick shells, the larger ones adapted massive shears attached to startlingly strong jaws. This could allow it to crunch through any prey item with ease.
Oh, and did I mention that it was the size of a bus?

Rendered in Photoshop