iTutor Biology Updates

Okay, this is going to be really hard to word/explain, so bear with me here. This occurred to me when we were studying evolution; specifically, the evolution of the whale. I was shown images of an evolutionary precursor/ancestor to the whale, which was little more than a large, crippled mammal with deformed legs. As I am given to understand, the fact that it survived was due to the fact that the area in which it appeared to have lived was surrounded by water. These useless legs eventually formed into fins, and became the modern-day whale that we know today, but that is not the point of what I'm trying to say. From what I understand, I believe that; if the environmental factors had not been in place, the whale would never have evolved. This is the very basis of evolutionary theory, I know; but here's my question: what if animals that are alive today evolved once, then were wiped out, but evolved again? That perfect, random set of mutations that allowed today's organisms to survive and reproduce: what if they occurred in the past, but the environment wasn't good for them? If you are wondering how the whale inspired this thought; the whale started out, in a sense, from individuals with a deformity, and only survived because the surrounding water rendered that negligible. Individuals with a deformity could happen all the time, even before the time that allowed it to survive. Once again, I'm sorry if I couldn't explain this very well...