It may sound like a Sy-Fy movie (and in fact was), but this fish is real -or was, 10 million years ago. Megapiranha paranensis was about ten times the size of the tiny but dangerous piranhas we know, and had a relative bite force that would put T. rex to shame.
The bite force of Megapiranha, which lived 10 million years ago, was extrapolated from the first field measurements of the biting force of Earth’s largest piranha today, Serrasalmus rhombeus or black piranha. One 2 ½ pound fish delivered a bite with a force of 320 newtons, or about 72 pounds, which is 30 times its body weight. The force is nearly three times greater than the bite force of an equivalent size American alligator.
Based on the 2 ½ pound piranha and other specimens tested in the wild, the scientists calculate that Megapiranha paranensis, which weighed approximately 22 pounds, could have had a bite force anywhere from 1,240 to 4,750 newtons – or 280 to 1,070 pounds – and possibly more.
Other scientists have previously estimated that T. rex slammed its jaws shut with 13,400 newtons, or 3,000 pounds of force, but that’s nowhere near 30 times its body weight.
The chart here compares apex predator fish (living and extinct) in bite force relative to size. Link -via reddit