There used to be some pretty sweet megafauna running around. Aside from Aepys, there were giant sloths, megalodons, mastodons, mammoths, and, my personal favorite, Ursus spelaeus, the cave bear. Giant bears who lived in caves. You would think such an awesome beat would be a fearsome predator, but in fact they seemed to have been herbivorous.
There is a book called The Clan of the Cave Bear, but sadly it is not really about bears at all. Though I do remember the movie, starring Darryl Hannah, had a pretty cool (for the time) sequence of a cave bear beheading a neanderthal. Unfortunately the neanderthals got even by hunting the cave bears to extinction.