What pit bull was used for the standard look of American kennel club registered dogs?

There is no single pit bull that was used to establish the standard look of American Kennel Club (AKC) registered dogs. The AKC does not recognize the pit bull breed, which is more accurately called the American Staffordshire Terrier.

Here's why:

* The AKC doesn't register pit bulls: The AKC recognizes and registers breeds like the American Staffordshire Terrier, the Staffordshire Bull Terrier, and the American Bulldog. These breeds are distinct from the pit bull, which is a term often used to refer to a mixed-breed dog or a dog with a certain appearance.

* Breed standards are developed through selective breeding: The breed standards for AKC-recognized breeds are based on generations of selective breeding and are established by breed clubs, not by a single dog.

* No single dog defines a breed: While certain dogs may be considered influential in the development of a breed, there is no one dog that defines the entire breed standard.

In summary, the "standard look" of AKC-registered dogs is based on the breed standards of various recognized breeds, not on any specific pit bull.