A rather astonishing new study suggests that ancient humans battled with giant ground sloths long ago, and the beasts would have been quite formidable for hunters to deal with. Totally unlike the lazy sloths we know of today, these giant sloths would have been strong, aggressive, and swinging dangerous claws at their human attackers.

The fascinating study examines 10,000 year old footprints to determine exactly how humans hunted this prey, finding that our ancestors may have used misdirection as a clever trick to defeat the sloth. The findings, published by researchers at Bournemouth University in the journal Science Advances, show that human hunters had to contend with a much different world than we do.

The giant ground sloth likely went extinct around the end of the Ice Age, but their footprints remain. These particular footprints were found at White Sands National Monument in New Mexico near the Trinity nuclear site, where the U.S. space program was born. It has become a major archeological site in recent years.

“New research explains the significance of footprint tracks found at a historic national park in the US,” Bournemouth said in a statement. “Researchers from Bournemouth University worked with colleagues in the US to excavate and analyse fossilised footprints that tell the story of a group of humans tracking and hunting a giant ground sloth.”