>>5003549 (OP) the better question is why xenarthrans in general were so uncompetitive with the NA meta. It's basically just these guys and the giant armadillo that survived in the megafaunal range and they're both kind of at the bottom of it. NA mammals like horses and camels ended up doing fine in Eurasia on exposure but basically every SA animal got raped and eaten.
>>5003565 Only cool critters in SA are jaguar, anteater, maned wolf and alpacas, everything else is kind of mid really. Ground sloth and glyptodons dissapeared just few thousand years ago, so sad.