A fictional animal based on the glyptodon and a palaeoburrow (ichnofossil) found in the State of Rio Grande do Sul, Brazil. Scientists say that this mega-tunnel was created by a long extinct species.

What Giant Beasts Carved Out these South American Mega-Tunnels?

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Immense tunnels found in the heart of the jungle in Brazil are thought to have been the den of a gruesome wild animal. Experts doubt that huge burrows were created by a natural geologic process and suggest that they are the creation of an ancient species of giant armadillos or ground sloth instead.

Gigantic Tunnels Discovered in Brazil are Not Nature’s Creation

According to scientists, the fact that the gigantic tunnels cannot be explained by any natural geologic process, as well as the enormous claw marks all over their walls, consolidates the theory that these tunnels were most likely carved out by an ancient species of giant sloth.

In 2010, Amilcar Adamy from the Brazilian Geological Survey, started scrutinizing the cave in Rondonia, western Brazil. Adamy’s goal was to connect the caves to some kind of natural process, but it didn’t take him too long to understand that such a thing would be historically and scientifically inaccurate. "I'd never seen anything like it before. It really grabbed my attention. It didn't look natural," Adamy told Discovery magazine .

Claw marks left in the tunnels.

Claw marks left in the tunnels. (Courtesy: Heinrich Frank )

However, it wasn’t until Heinrich Frank from the Federal University of Rio Grande do Sul in Brazil launched his own investigations on the area that this theory became viral. When he arrived at the caves to examine them, he found characteristic grooves in the weather-beaten surfaces, "Most consist of long, shallow grooves parallel to each other… apparently produced by two or three claws. These grooves are mostly smooth, but some irregular ones may have been produced by broken claws," he wrote, as Daily Star reports .

Tunnels Belong to a Lost species of Giant Armadillos or Ground Sloth

Researchers are now confident and suggest that the burrows belong either to a lost species of giant armadillos or ground sloth. Apparently, the huge beasts that dominated our planet before Homo sapiens took over didn’t only leave their bones behind as evidence of their existence, but some of them also left extremely long tunnels like the ones found in South America.

A closer look at the claw marks left in a tunnel.

A closer look at the claw marks left in a tunnel. ( Heinrich Frank )

Several studies have taken place during the past fifteen years, investigating and trying to explain all the amazing feats of animal engineering. Heinrich Frank has been a leading figure in most of the investigations, “For most of the fossil vertebrates, you have only the bones and no clues about their living, how they behave, if they live alone or in groups,” Dr. Frank told IFLScience .

He continues by explaining the importance of the discovery of these tunnels,

“It is very rare, in Paleontology, to have this kind of information about an extinct species. This is the main reason why paleotocas are so important. Additionally, they give us a little bit of information about distribution and abundance of certain animals with different habits.”

Remains of a Giant ground sloth (Eremotherium laurillardi).

Remains of a Giant ground sloth (Eremotherium laurillardi). ( CC BY SA 2.5 ) Giant ground sloths may have created the tunnels.

So far, more than two thousand burrows have been found. Experts think they were dug between ten thousand and eight thousand years ago, even though no scientific analysis has yet taken place to properly date them. Scientists suggest that these tunnels, also known as “paleotocas” were most likely dug by giant ground sloths, like the Glossotherium, which were common in the Americas from the Pliocene to the late Pleistocene. Other experts suggest, however, that they could have been the burrows of giant armadillos.

Glossotherium robustum (syn. Mylodon robustus).

Glossotherium robustum (syn. Mylodon robustus ). ( Public Domain ) These extinct beasts are another possibility for what may have created the mega-tunnels.

Paleotocas Were First Discovered Almost a Century Ago

Paleotocas were first found in Argentina during the late 1920s, but it wasn’t until later that Brazilian researchers started exploring them in many different locations within their country. Scientists have claimed that when these tunnels were formed, the area’s geological conditions were significantly different than today. It is believed that back then the Amazon forest was an enormous savannah swarming with immense life like mastodons, giant alligators, and these giant burrowers.

Despite the detailed explorations of the area during the past two decades, we still don’t know much about these paleoburrows. Dr. Frank tells Discover Magazine , “We need to figure out the patterns. We’re starting to understand this better. And from there, we’ll be better able to infer what kinds of different animals were digging them,” implying that there’s much more work to be done before we fully comprehend how and what kind of animals created these enormous tunnels.


Not one mention of the type of material the tunnels are carved into. Is it compacted mud, soft stone, or hard rock? Obviously not written by a scientist.

Are they simply "lava tubes" similar to those in North Queensland, Australia? Just asking!!!!

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