In the late Pleistocene, at least four elephant species lived in North America.Under a scientific framework, captive elephants in the U.S. could be introduced as proxies for these extinct animals.

• 北美洲在更新世晚期至少有四种象科动物，因此就科学理论来说，豢养的大象应该可以引进美国，当做那些已灭绝动物的分身。