You wanted the feedback! I think it's a valiant effort. I have absolutely no skill with using computer programs for artistic purposes (while with a brush I'm average) so you are surpassing me by quite a bit

I don't know the exact specification for pixels but I know it's small so it's hard to make anything look like anything remotely resembling what we know.

One suggestion about the Bison might make it the very dark, black Version who is shaggy with a barrel chest.

Maybe you could make the alligator have it's tail whipping around on it's back to shorten him up a little.

I have been trying to think of a good way to do a snake, but I'm coming up short. Maybe if you were making more than just a snake you could modify it, but just a snake is hard. If you want to keep the sidewinding aspect, try to make an underbelly and not so much of a waving aspect to them so they look like they are moving and not an ariel view.