Please be advised that whatever you propose in the way of an answer will not be received as an article of fact, but as an article of faith.
Check #337, a fossil whale with legs and arms. Oooops, guess that's impossible.
My point with the modern humpback skeleton is that it even has floating pelvic bones, and there are descriptions from whalers with even greater vestigial structures depending on the species, etc. Believe what you want. I'm going with the story visible in the bones.
How do we know you're not a space alien?