I agree. Many animals 'punch' for defence or attack. Kangaroos, primates, some mice and rats... there are many. The thing that has to be pointed out though is that a 'proper punch' cannot be served by a kangaroo or primate etc. They all have the issue of open handedness (or pawness) and thus renders a proper punch less effective in itself. Most of these animals far outweigh humans in sheer muscle strength so their 'punches' are still effective, but they cannot 'lock and load' the fist as we can. I wouldn't like to stand and receive one all the same ;)