I should have been clearer, I meant people who hunt for trophies and use rifles I don't get how they can feel an achievement because they used a rifle. I never meant hunting in general with a rifle is wrong. I just meant there is no real "sport" or greatness in being able to shoot an animal. Hunting for food with a rifle is fine, I have nothing against that and I'm a vegetarian... I'd rather some shoot an animal and kill it very quickly then use the meat etc than an animal be kept in a factory style environment and "processed". At least the animal was free and happy before it was killed and then the person is grateful for it, it's all good and natural. That's different to hunting something like Tigers though.
Oh sorry didn't realise that you wanted an answer to that, thought it was rhetorical. lol
I'm really not sure, I mean the Mammoth was HUGE. It needed a lot of food, herbivores need to eat far more than carnivores for energy. So you can imagine how much a Mammoth would need, massive forests, but with far apart grown trees etc. I don't think there is a big enough area for them now. The Mastodon I'm not sure on it's habitat. The sabre tooth cats where huge, if you put those into any ecosystem today they would obliterate the larger pray. They would devour those massive Bison and even take down Mammoths. They would take all the prey from other big Cats and Dogs.
The way i could see them doing it is creating an Island like Jurassic park. lol They would have to let the animals create their own ecosystem again, but we all know what happens in those films. lol