I just inject 3 (perhaps vague) comments:
1) The "survival of the fitest" phrase is widely considered to be merely an approximation - not to be taked too literally.
2) It has been vaguely touched upon, but seemingly not explicitly stated - The "survival of the fitest" is a matter of statistical probability - Not all the "most fit" survive to reproduce, and some of the "less fit" do survive to reproduce.
3) Concerning the asteroid impact - My impression of things is that the environment of the time was already undergoing a radical, if not as sudden of a change as an asteroid impact. A major extinction event was happening prior to the asteroid showing up. Perhaps a worthy topic would be "How significant was the asteroid impact, in the K-T extinction event?". But I'm not going to start the topic.
Moose
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Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment.
My big page of Creation/Evolution Links
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