Fossilized Footprints Show Ice Age Hunters Ganged Up on Giant Sloths

They just don't make sloths like they used to. Giant ground sloths from the Ice Age wielded razor-sharp claws and stood 7 feet tall, and new evidence suggests that humans—even children—stalked and hunted them.

By analyzing fossilized footprints found in the salt flats of New Mexico, researchers at Bournemouth University in the UK figured out how prehistoric humans managed to outsmart these furry behemoths. The tracks, which are between 10,000 and 15,000 years old, show two overlapping sets of footprints belonging to both man and beast. Researchers deduced that these early hunters aligned their footprints with the sloth's to avoid detection and sneak up on their prey. The findings were published in the journal Science Advances.

"Getting two sets of fossil footprints that interact, that show you the behavioral ecology, is very, very rare," Matthew Bennett, one of the researchers at Bournemouth, told Reuters.

They also found another set of human footprints, leading researchers to believe that hunters traveled in packs and ganged up on the sloth, with one group distracting the animal from a safe distance while another attempted to land a fatal blow. The clue was in marks they dubbed "flailing circles," which suggested that the sloth rose on its hind legs and swung around to defend itself. Anywhere they found flailing circles, human footprints followed.

The presence of children's tracks also showed that hunting was a family affair, but it probably wasn't as fun (or as safe) as going to a modern-day zoo. The prints were taken from New Mexico's White Sands National Monument, which has the "largest concentration of human and Ice Age giant megafauna prints in the Americas," according to researchers. The remote part of the park where they conducted their research is not open to the public.

Modern sloths are related to the giant ground sloth, which went extinct about 11,000 years ago, likely due to over-hunting by humans, scientists say. The fossilized footprints were digitized and preserved for future research using 3D modeling techniques.