Wow. When I was talking about restoring the plains, I meant things like buffalo and wolves and such. I've never even heard of such an argument for exotic animals (though I'm pretty sure horses are non-natives brought over by the Europeans). I don't know how I feel about that, because in all fairness, with the exception of maybe Mastadons/Mammoths, they all probably died off of natural causes in North America. Though, I am reminded now about the Elephant Sanctuary in Tennessee, so it's not like it couldn't be done . . . Edit: And bears. America could always use some more bears.Starting with giant tortoises and wild horses, then moving toward lions and elephants, the authors provide a number of case studies for "Pleistocene Rewilding" and argue such introductions would contribute biological, economic, and cultural benefits to North America. The authors acknowledge that there are substantial risks and challenges; the risks of inaction may be even greater, however, including the continued global loss of megafauna.
https://www.scientificamerican.com/article/serengeti-in-the-dakotas/ That's the article I was originally looking for. They argue that pretty much every large predator in North America was wiped out by human migration.
It's a really interesting concept and I can see some of their argument as well as concerns of citizens about such a thing getting out of hand. At the same time though, it sounds more like a fantasy idea instead of a real attempt at sustaining an ecosystem.