The context in which they are found makes them more extraordinary still.

The same sediment surfaces that preserve human trackways also preserve the tracks of animals that no longer exist — members of the Pleistocene megafauna that went extinct at the end of the Ice Age, between roughly 12,000 and 10,000 years ago, in a pattern that affected large mammals across the globe and for which the causes are still debated.

In North America, this extinction event eliminated the mammoths, mastodons, giant ground sloths, American horses, American camels, short-faced bears, saber-toothed cats, and dozens of other species.

At White Sands, some of those animals left their traces in the same mud that human feet pressed into.

Giant ground sloths — megatheria, some of which reached the size of modern elephants — left footprints at White Sands that are remarkable in their own right.

The sloth’s foot was wide and plantigrade, leaving a large, distinctive impression quite different from any modern North American animal.