I love the idea that it is not set in stone which animals go extinct. The sabretooth, mammoth, glyptodon, elasmotherium, thylacine etc. should have a decent chance of surviving. Similarly just about every animal we know today should have a chance of going extinct 'instead'.
That said, I do think a mapscript should at least have an option to ensure the possibility for all civs to get mount animals (by which I mean horses OR camels, because elephants are too specialized and I believe all others require a wonder).
Also, why can't we make alcohol from potatoes? Seems like a bug.