Hi Robert,
if the Ark was real then the post flood world would be populated by the creatures off the ark.
Makes sense if the ark were real (which was the assumption in this thread). But...
The bible says there were seven pairs of the clean and two of the unclean. It doesn't say what clean/unclean were.
it follows the clean would dominate over the unclean.
Uh, no? If cows are clean, and tigers are unclean, the cows still get eaten and would definitely not dominate. And since it is likely that either the cows got eaten or starved to death on Mt Ararat, something else must have happened.
On the other hand, if the clean dominate over the unclean, that would mean that some sort of bacteria is probably the cleanest of all, since their kind is probably among the most successful and most dominant creatures ever and are very likely to survive god's own supposed favourites (namely, us) by many millions of years.
only the fossil record shows the great diversity after the flood.
It would, if it also showed evidence for the flood. But it doesn't.