By George Grow
02 May, 2018

A desert in the American Southwest provides evidence of a hunt from long ago.

Scientists found footprints from a hunt involving ancient human beings and a large prehistoric sloth. They discovered the footprints in what is now the White Sands National Monument in the state of New Mexico.

The discovery is extremely rare. The researchers say it could change scientists' understanding of how ancient humans interacted with large animals. It also may show whether our ancestors were responsible for the disappearance of the giant ground sloth.

Reconstruction based on fossil footprint evidence shows how human hunters stalked giant ground sloth to distract them before trying to land a killing blow. (Photo credit: Alex McClelland, Bournemouth University)
Reconstruction based on fossil footprint evidence shows how human hunters stalked giant ground sloth to distract them before trying to land a killing blow. (Photo credit: Alex McClelland, Bournemouth University)

Footprints in footprints

The researchers found more than 100 footprints dating back between 10,000 and 15,000 years. They were found among particles of gypsum, a soft mineral, in the desert.

The prints seem to show humans following giant ground sloths. The animals could reach the size of an elephant. Science magazine says they disappeared about 11,000 years ago, around the end of Earth's last Ice Age. That would be about the same time the first human civilizations appeared on our planet.

The footprints show that, sometimes, the human hunters walked directly in markings left by the giant sloth. The distance between steps for a giant sloth is greater than that of a human step. Researchers say the markings show one human appeared to get very close to a sloth on tip-toe.

In places where the human footprints appear close to the sloth's markings, the animal suddenly changes direction. The researchers found what they call "flailing circles," where it looks like the animal stood up on its back legs to defend itself with its front legs.

Risky hunting

Hunting such a large animal "would have come with huge amounts of risk," said Matthew Bennett of Bournemouth University in England. He is a geology professor and the lead writer of a recent report on the discovery. The findings appear in the scientific publication Science Advances.

"You know, if you were chasing a small rabbit or something, little risk associated. But going head to head with a sloth, the chances are that you might come off badly."

With the newly discovered footprints, Bennett said "we can begin to understand how they did it." "That gives us a better understanding whether we are guilty or not" of hunting the animals to extinction.

Martin Lockley is a paleontologist. Paleontology is the area of science concerned with fossilized remains of plants and animals. Lockley taught at the University of Colorado, in Denver, before his retirement. He was not involved in the new research.

Lockley said "It is very rare if not unique to see unequivocal evidence of human interactions with large vertebrates based on tracks.

He added, "There are only a handful of ancient human footprint sites in North America, making this one of the best."

The researchers say there are likely other footprints to be found at the White Sands National Monument.

I'm Ashley Thompson.

Steve Baragona reported this story for VOANews. George Grow adapted his report for Learning English. Ashley Thompson was the editor.

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Words in This Story

tip-toen. the action of touching the ground only with one's toes

associatedadj. closely connect with another person or thing

extinctionn. the act of making something die out

uniqueadj. special; unusual

unequivocal adj. very strong or clear

vertebrate – n. any of the bony pieces making up the backbone

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