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On the Trail of the Mapinguari

Donate Are ground sloths that somehow survived their extinction responsible for cryptid sightings in the Amazon?  

by Brian Dunning

Filed under Cryptozoology

Skeptoid Podcast #888
June 13, 2023
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On the Trail of the Mapinguari

Today we're going to take our machete and hack our way into the jungles of the Amazon, in search of a folkloric character that some say exists as a real creature. Some say it's a species of bear, some say it's an undiscovered Bigfoot-like primate, and some say it's a — well, we'll get to that. But until Americans got there, the Brazilians always considered their mapinguari to be yet another character from their folklore. That story has now changed — a lot.

The mapinguari has traditionally been one of many characters said to be spirits that protect the forest and its animals from hunters, woodcutters, and any disrespectful people who come in and are loud, who make camps and leave messes, or build fires. As with nearly all such characters, a few people have reported actually seeing one. The mapinguari is said to be quite remarkable in its appearance. It's the size of a large human, with a frightening single large eye on the front of its head, its mouth enormous and located way down in the middle of its belly, its feet turned backwards to make it difficult to track, and covered in long, shaggy, reddish fur. It roars terribly, and gives off a stench so bad it can drive to madness those unlucky enough to inhale it, even so powerful as to render them mute for the rest of their lives.

Beginning in the latter half of the 20th century, American and European cryptozoologists heard these reports and identified the mapinguari as an unknown primate, literally a Bigfoot of the Amazon. This was first reported in Bernard Heuvelmans' 1958 On the Track of Unknown Animals in which he described its behavior as "Just what one might expect of a powerful great ape." From then on, nearly every book published on cryptozoology for half a century included the mapinguari as an example of a great Bigfoot-style ape.

The thing with its feet being turned backwards, while not typically characteristic of Bigfoot reports, is common in folklore. Such a creature would confound those who try to track it, because its footprints seem to go in the opposite direction. These are found in the folklore of cultures all around the world, and there are several others in South America. Besides the mapinguari, Brazilian folklore includes the curupira, a small man with bright red or orange fur, or a boy with red or orange hair, who harasses lumberjacks and hunters, playing tricks on them and then being impossible to track, as his backwards footprints merely lead them astray. Particularly mischievous is the chullachaqui, a protector of the forest, who can shape-shift and take on the form of friends and family members to lure people into the jungle. Normally the chullachaqui looks like a small, ugly man with mismatched feet. One points forward and the other points backward, and either or both feet might take on a different form: a hoof or the footprint of some prey animal, making him nearly impossible to track.

The mapinguari in folklore has always traditionally been a normal human, a shaman who discovered the key to immortality, which angered the gods who punished him by turning him into a hideous creature with only a single eye, one huge mouth down in the middle of his abdomen, his feet turned backwards, and covered in reddish fur. Prior to 1993 — which isn't all that long ago — any mention of the mapinguari was in this folkloric context where he slotted in neatly beside the curupira and the chullachaqui, except from the Bigfoot and cryptozoologist community who claimed the mapinguari as one of their own.

But if you search the web for the mapinguari today, you'll find something very different: that it is an actual animal, a species of ground sloth that somehow survived its extinction. Virtually every mention of mapinguari published after 1993 is this radically new version. Here are a few sample headlines:

Mapinguari Sightings: Is the Giant Ground Sloth Still Alive in the Amazon?

This Sloth Monster Is Said To Roam The Amazon Rainforest — Here's What The Evidence Says

In Brazil, U.S. Scientist Thinks He's Close to Finding Huge Sloth Thought to Be Extinct

It sounds like the potential identification of the mapinguari as a ground sloth is a pretty widely accepted idea. It sounds like we might find papers published on the topic. It sounds like any paleontologist who specializes in ground sloths might be likely to go off lecturing on the subject at length. However, it turns out the truth is very different. The entire notion is that of one man: Dr. David C. Oren. Oren first went to Brazil as a postdoc in ornithology in 1977 — and ended up staying there permanently. Over the next decade and a half, he heard stories of the mapinguari, and to him, they sounded a lot like giant ground sloths, believed to have been extinct for thousands of years. He took a position at a research institution in the Amazon which allowed him plenty of time to pursue his hypothesis on his own. He had nothing but opposition from other scientists to his idea — Brazilian scientists certainly would have known if giant ground sloths were stomping around — so Oren always had to fund his own expeditions into the jungle, collecting stories and hoping to find evidence.

Then, by 1993, he was ready to put his idea out there. He wrote an article, "Did ground sloths survive to Recent times in the Amazon region?" and published it in Goeldiana Zoologia, the journal of the institution where he worked. In the article, he lays out the basics of the various giant ground sloth species known to have lived throughout the Americas; and then he discussed its similarities to all the details he'd learned about the folkloric mapinguari. Let's go through these.

    • Reddish fur. Many samples of fur from mummified ground sloth remains are reddish, as is the mapinguari in some reports.

    • Feet turned backwards. Ground sloths' toes were curved inward when they walked, which — though not terribly convincingly — could be consistent with a footprint that appears to be backwards.

    • Invincibility to weapons, except around the navel. Oren cited that a very few species of ground sloths had dermal ossicles, the bony tissue in the skin that gives animals like the sloths' relative the armadillo its armor plates. He felt this could explain the creature's legendary resistance to gunfire everywhere except its belly, where it had no ossicles.

    • Monkey-like face. In a bit of a stretch, Oren noted that the face of a ground sloth did not look at all like a monkey, and neither would that of a one-eyed mapinguari. Thus, a possible match.

    • Human size. The smaller species of ground sloth were indeed about as tall as a human.

    • Tracks. While ground sloths left tracks that were vaguely human shaped, some legends of mapinguari tracks had round feet ("like the bottom of a bottle pressed into the ground") instead of backwards feet. In an admitted speculation, Oren opined that a ground sloth's powerful tail (used like the third leg of a tripod) might perhaps leave a round print.

    • Feces. Ground sloth feces, which survive as coprolites in great quantities in certain caves, looked just like that of a horse, and this was a feature of mapinguari reports as well.

    • Vocalizations. As their vocal structures are broadly similar to today's sloths which can sound like a baby crying, we can deduce that ground sloths may reasonably have sounded something like a human shouting; and that matches the mapinguari reports.

Oddly, Oren did not address at all the trait that I find the most extraordinary: the place those screams are coming from, the giant mouth in the middle of its belly.

So how do Oren's matches sound to you? A few hits, a few misses, and a whole lot of speculation and uncertainty. Recall that even the hits are against unverified anecdotes. No evidence exists to indicate that the mapinguari is anything but a purely folkloric creature, except for the anecdotes Oren has collected. He concludes:

There is little doubt in my mind that the mapinguari legend is based on human contact with forest-dwelling mylodontid ground sloths in Amazonia.

Oren's paper was picked up by major newspapers such as the Los Angeles Times, and before you knew it, "scientists think giant ground sloths still survive in the Amazon." Except they really don't, given that there's no evidence and no reason to suspect they might. The history of ground sloths is well known, and we've solid reasons to conclude they are, in fact, extinct.

Ground sloths first evolved in South America several million years ago, and spread upwards through the continent from there. By the time of the most recent ice age, many species were well established throughout the Americas, the largest being bigger than modern elephants. That glacial maximum is when sea levels were low enough that humans first entered North America. These two events combined to spell doom for the ground sloths: they had predators hunting them for the first time ever, and climate and related environmental changes to which they were poorly adapted placed unsustainable pressures on their population. By 10,000 years ago, most in North America were gone. Those in South America lasted a few thousand years longer as human populations were just becoming established. The very latest of the giant ground sloths were those on the Caribbean islands, which endured until less than 4,000 years ago, according to carbon dating of their remains.

Wherever we find their fossils, they are relatively abundant until their extinctions. From that point on, they are completely absent from the fossil record. Species that did survive, such as the tapir, the jaguar, even the manatee, are found in the fossil record. For a much larger animal to evade not only the fossil record but to also leave no other evidence of its existence of any kind, is — in short — just not plausible.

And it's also not necessary. Anecdotes of monsters in the jungle exist all over the world, monsters which have never been found and never left any evidence. Recall Hyman's Categorical Imperative: Do not try to explain something until you are sure there is something to be explained. As with Bigfoot, the Loch Ness Monster, and the Mongolian Death Worm, we don't have sufficient evidence to conclude that the mapinguari is anything other than the character from Brazilian folklore it has always been. Leaping to the identification of "ground sloth" is premature, because we don't yet have anything in need of an identification. And until we do, folklore it shall remain.

By Brian Dunning

Please contact us with any corrections or feedback.


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Cite this article:
Dunning, B. "On the Trail of the Mapinguari." Skeptoid Podcast. Skeptoid Media, 13 Jun 2023. Web. 13 Jun 2024. <>


References & Further Reading

Coleman, L., Clark, J. Cryptozoology A to Z. New York: Fireside, 1999. 150-151.

Heuvelmans, B. On the Track of Unknown Animals. London: Rupert Hart-Davis, 1958. 323-327.

Long, W. "In Brazil, U.S. Scientist Thinks He’s Close to Finding Huge Sloth Thought to Be Extinct." Los Angeles Times. California Times, 30 Mar. 1994. Web. 31 May. 2023. <>

Oren, D. "Did ground sloths survive to Recent times in the Amazon region?" Goeldiana Zoologia. 20 Aug. 1993, Number 19: 1-11.

Rohter, L. "A Huge Amazon Monster Is Only a Myth. Or Is It?" The New York Times. The New York Times Company, 8 Jul. 2007. Web. 31 May. 2023. <>

Shuker, K. The Beasts That Hide From Man. New York: Paraview Press, 2003. 289.


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