It's a fucking physiological fact! A pit bull's jaws are different to most dogs, in that they lock onto their prey! The jaws have a different configuration! And they shake their prey till it's dead! Google it! There are X-rays of pitbull dog breeds that prove that their jaws are designed to lock onto their prey! There have been people who have been bitten, and the dog, even when sedated, just cannot let go
I did google it. And I posted links above. Staffordshire bull terriers, which is what we're discussing, do not have radically different jaw anatomy from other dogs breeds. The shaking, as a PP said, is a terrier trait, not one specific to Staffies.
As for pit bulls, I found this "NO! According to Dr. I. Lehr Brisbin, Ph.D., senior research scientist at the University of Georgia and an expert in training, handling, behavior, and the anatomy of bull dog breeds, “The few studies which have been conducted of the structure of the skulls, mandibles, and teeth of [American Pit Bull Terriers] show that, in proportion to their size, their jaw structure and thus its inferred functional morphology, is no different than that of any [other] breed of dog. There is absolutely no evidence for the existence of any kind of ‘locking mechanism’ unique to the structure of the jaw and/or teeth of the American Pit Bull Terrier.”
Source: American Dog Breeders Association"
From this site. Frankly, unless you start linking to some actual evidence, I'm going to assume you're on a wind up.