Thread by @tradingMaxiSL

These tunnels were dug by a Giant Ground Sloth that lived 10,000 years ago in Brazil. The third photo are the claw marks 🧵

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2. Usually, tunnels are made either by human engineers or flowing water. But near Novo Hamburgo, Brazil, tunnels large enough to drive a car in were dug by neither — they’re the work of ancient, giant sloths.

3. The burrows are at least 8-10,000 years old, and no geologic process explains them. However, massive claw marks line the walls and ceilings, making ancient giant sloths the prime suspects.

4. Known since the 1930s, these structures were first attributed to early humans. Until 2010, they weren’t deeply studied. Then, Amilcar Adamy, a geologist, investigated a cave in Rondonia, finding Brazil’s largest paleoburrow.

5. The paleoburrow in Rondonia is over twice the size of the second largest. Adamy studied it thoroughly, concluding it didn’t look natural and must have been dug by ancient creatures.

6. Heinrich Frank, a professor at the Federal University of Rio Grande, found a similar tunnel near Novo Hamburgo. His team explored the cave and discovered 1,500 more in Rio Grande do Sul.

7. Researchers now think huge ground sloths — as big as African elephants — or extinct armadillos dug these tunnels. Some burrows stretch hundreds of feet and branch in many directions.

8. The largest burrow is 2,000 feet long, 6 feet tall, and 3 to 5 feet wide. To create it, animals had to dig 4,000 metric tons of dirt, likely requiring several generations of effort.

9. Most paleoburrows are in Rio Grande and Santa Catarina, southern Brazil. Few exist in northern Brazil or South America, suggesting the ground sloths had a limited range—or undiscovered tunnels exist elsewhere.