There are a lot of things about Sonic that don't make sense. Hedgehogs aren't usually blue, for instance. The species isn't bipedal either, nor do they have the ability of speech -- and don't get us started on at huge single eyeball he's got in his head. The weirdest part? How a gangly-legged rodent can run at such incredible speeds. If we want to be just a tiny bit more anatomically correct, Sonic should look a bit more like this:

sonic