I am not an evolutionary biologist (I do write software for a lot of research biologists) but I don't think there was anyone walking around with tiny jaw muscle

I am not an evolutionary biologist (I do write software for a lot of research biologists) but I don't think there was anyone walking around with tiny jaw muscles and a huge jaw. I suspect the development of the jaw is related to the same gene. What that article attempts to say, and fails to do it, is that HUGE changes often happen in a single generation. There's a contagious non lethal dog tumor that used to be a dog, as in an individual dog.