@PeterBrannen1 The “Original Extent” is more a function of historical interactions than actual taxonomic range. Disease and the subsequent depopulation during the contact period allowed bison to migrate east into lands they had not occupied since the end of the Pleistocene. Check out Sasso 2014
@HarmlessYardDog This is not entirely true. Bison, for example, in the Driftless Area only appear after the Oneota period, likely as a result of the lower human population. Before this, there were minimal bison specimens from the area, and the ones that do show up are scapulas, most likely trade.