Imagine a giant fish 30 feet long with jaws like a chopping block. Anything that found itself inside the mouth of this fish ended up dead.
382 million years ago nature came up with a new killing machine that dominated the Late Devonian period for over 30 million years. Its name was Dunkleosteus and there has never been another fish like since it went extinct. And its a good thing for us that it did. Dunkleosteus was a placoderm (Armored Fish) meaning that its front half of its body was made up of bone and hard tissue. kind of like a head made out of a turtles shell. It's thought that this large fish would have roamed the shorelines like a modern day great white. How fast this animal could travel through the water is still unknown but there is one feature about this fish that is just terrifying.
Dunkleosteus possessed a four-bar linkage mechanism for jaw opening that incorporated connections between the skull, the thoracic shield, the lower jaw and the jaw muscles joined together by movable joints. This mechanism allowed it to open their jaws in 20 milliseconds and complete the whole process and close in 50–60 milliseconds. That is ridiculously fast for any animal and this was done with the resistance of deep water around it.
The four-bar jaw link created a bite