Mammoths, and other large mammals, only went extinct in North America when they were hunted to extinction by 12,000 years ago, just as soon as humans made it over the Bering. Mammoths, giant sloths, etc, are a natural part of our ecosystem and thus should be returned to the wild in North America.
They should restocked to the ecosystem in Massachusetts.
Thank you for volunteering your private yard for housing.
Source, please. Not that it couldn't happen. Turn them loose in someone's wheat field and it could happen again.
There are those who would like to return our entire ecosystem to 12,000 years ago, but don't expect that will do much for our standard of living.
Don't forget to return the saber-toothed cats to the L.A. Area, either, while y'all are at it.
You might want to catch up on the developments in pre-clovis archaeology, too. Seems humans were here a lot longer than 12,000 years.