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The reverse trek was made by four different kinds of ground sloths, oversized armadillos, terror birds, capybaras and even a marsupial.

When the skeletal remains of a giant ground sloth were first unearthed in 1796, the discovery marked one of the earliest paleontological finds in American history.

They lost their biggest natural seed-disperser, the giant ground sloth, to extinction at the end of the Pleistocene Epoch, and the mice that now carry the seeds can’t move them very far.

With their thick leg bones attached to wide-spreading hip bones and a sturdy tail, giant ground sloths could have stood upright on their hind legs to reach leaves high in trees.

Some 13,000 years later, that sabertoothed cat’s jawbone sits in a museum drawer alongside those of a western horse, ancient bison, dire wolf, ground sloth, and yesterday’s camel.