The American Aboriginals are certainly an interesting lot. Although like Megas' has said, most natives south of the Arctic are Pre Dorset. As far as Clovians go, nobody is really sure what happened, some think Toba (or the ice age following it) wiped em' out, or if that didn't do it the arrival of Pre Dorset peoples certainly did, whether it was genocide or they merged. The debate is still pretty heated, however, although the Natives down in the US seem to disregard a lot of compelling evidence to suggest their people weren't the first in the Americas.

The Blackfeet, as it stands are probably the greatest argument for the Clovians, maybe even descendants.