Why didn’t the mega fauna of Asia and Africa die out as well? I would have loved to see that huge armadillo cousin Glyptodont with its mace like tail walking near a stream during the last ice age.
The theory, which I don’t find entirely convincing, is that African, and to a lesser extent Asian, megafauna were around when humans evolved and had time to learn to adapt to them.
In the Americas, Oz and elsewhere the animals weren’t adapted to this uniquely effective predator and were wiped out by us.
I hear there are still Rodents Of Unusual Size (ROUS).