In the Middle Pleistocene, "Arctodus pristinus" evolved into "Arctodus simus", which inhabited most of North America, from Alaska to Mexico. "Arctotherium angustidens" was replaced by smaller, medium-sized species- first "Arctotherium vetustum", then by "Arctotherium bonariense" and "Arctotherium tarijense". "Arctotherium wingei" was the only known species of "Arctotherium" to inhabit tropical South America and Central America.