A Megatherium reconstruction by Robert Horsfall

A Megatherium reconstruction by Robert Horsfall

A ground sloth hide found in the Cueva Ultima Esperanza Cave

A ground sloth hide found in the Cueva Ultima Esperanza Cave

Patagonian ground sloth

Ground sloths were a family of mammals in the sloth family that inhabited the entirety of the Americas from 20 million years ago to about 10,000 years ago. Though some small pockets survived in Patagonia until as recently as 5,000 years ago. Other, smaller ground sloth species lived even more recently in the Caribbean, dying out 2,000 years ago. There were many species, with some being the size of dogs and others comparable in size to elephants. They were herbivorous and used their massive claws to cut down branches and leaves to eat from the treetops.


Although tales of ground sloths or Megatheriids surviving into modern times in South America are commonly associated with the Amazon rainforest, there is a substantial number of sightings and folklore in Patagonia as well. In fact, the first surviving ground sloth sighting came from southern Argentina. 


In the 1870s, Argentina’s secretary of state, Ramon Lista, saw a creature he likened to a gigantic, reddish-grey-furred, armourless pangolin. He shot at it, but the animal brushed it off and continued walking away. 


In the early 1890s, Argentine naturalist, zoologist, and paleontologist, Florentino Ameghino was told by the local Tehuelche people in the interior of the Santa Cruz province that there were ox-sized nocturnal animals that lived in hollowed out burrows. They explained to Ameghino that they were frightening and strange looking animals with long claws and dense fur. They were extremely difficult to kill because their hides were impervious to arrows and bullets. At some time around 1921, a Tehuelche man claimed that his father would occasionally encounter a 13-foot-long ground sloth-like creature as wide as an ox around the Sarasola Cave in the Chubut province of Argentina.


From 1900 to 1901, British explorer Hesketh Prichard started an expedition, financed by the London based Daily Express, to find surviving ground sloths. During the expedition, Prichard was contacted by another explorer, Edward Chace, who told him that a Tehuelche man recently came across a trail of strange prints, which he described as if it was made by a wooden shoe, but with two cleats across the sole. He followed the tracks and came across the maker, a strange creature resembling a hairy pig, but was the size of a large bull. Although the expedition was unsuccessful, it was one of the inspirations for Sir Arthur Conan Doyle’s famous novel, The Lost World


There have been no Patagonian ground sloth sightings in more than 100 years, so they may be extinct or only live in areas so inaccessible, that nobody has seen one, or at least reported it to any newspapers or scientists. 


Some have pointed out the seemingly outlandish detail that in these ground sloth sightings, both in Patagonia and in the Amazon, they are described as being arrow and bulletproof. This is likely because ground sloth hides are very thick, and are covered in numerous warty bones, called dermal ossicles, like the mummified pelt found in the Cueva Ultima Esperanza cave (above). Ground sloths also had extremely thick and compact ribcages, that were so close together that each rib is almost connected. Having thick boney hides and massive armour-like ribcages would probably explain their alleged invulnerability to arrows and even gunshots.