Who carved South America's mysterious ancient tunnels? [pdf]

https://www.clp.unesp.br/Modulos/Noticias/401/paleoburrows-nature-2025.pdf

by Qem • 1 year ago

100 45 1 year ago

clp.unesp.br

stargrazer• 1 year ago

I wish there were more pictures.

staplung• 1 year ago

https://www.google.com/search?udm=2&q=paleoburrows

mmooss2• 1 year ago

https://news.ycombinator.com/item?id=43083213

bj85• 1 year ago

Giant sloths was not really on my list of expected answers but "One species, Glossotherium robustum, a South American sloth that lived between 4 million and 12,500 years ago, reached more than 3 metres in length and weighed up to 1,500 kilograms"

But who was really in charge?

tejtm• 1 year ago

Good question, species do not put that much compulsive effort into preemptive escape without cause.

IncreasePosts• 1 year ago

Maybe humans just used the claws of dead giant sloths to carve the caves for their own purposes.

Retric• 1 year ago

Thermal regulation is a possibility mentioned outside of predation.

Bears aren’t afraid of being eaten, but they still dig dens because they’re warm in the winter.

Qem3• 1 year ago

Giant sloths was not really on my list of expected answers

Despite not looking very alike at the first glance, sloths are grouped together with armadillos in the clade Xenarthra[1]. Both lineages descend from a common ancestor from around the time the dinosaurs went extinct. So it's not that surprising there were burrowing sloths. I guess the burrowing behaviour surely came handy to their shared ancestor by the time the dinosaurs were screwed by the asteroid that carved the Chicxulub crater[2]. What is mind-boggling for me is that once there were aquatic sloths[3]. Some sloths followed the steps from the ancestors of whales and dolphins, and rehearsed a return to sea. Unfortunately that evolutionary experiment was cut short when the gap between south and north america closed, isolating atlantic from pacific oceans and dooming the niche where the critters thrived. Had they persisted, I wonder if by now we could have whale-like sloths (whaloths?).

[1] https://en.wikipedia.org/wiki/Xenarthra

[2] https://en.wikipedia.org/wiki/Chicxulub_crater

[3] https://en.wikipedia.org/wiki/Thalassocnus

bloopernova• 1 year ago

Thank you for the aquatic sloth link, that's so cool!

beambot• 1 year ago

Manatees and dugongs feel like "whale-like sloths", though I have no idea if they're taxonomically related

adolph• 1 year ago

The giant sloth was the first thing that came to my mind. Nearly every time I'm at the grocery I think about the giant ground sloth theory of avocado evolution:

  A number of authors, including Connie Barlow in her 2001 book The Ghosts of 
  Evolution, have speculated that the avocado is an "evolutionary anachronism" 
  with megafaunal dispersal syndrome (a concept originally proposed in the 
  1980s by Paul S. Martin and Daniel H. Janzen), arguing that the avocado 
  likely coevolved dispersal of its large seed by now-extinct megafauna. Barlow 
  proposed that the dispersers included the gomphothere (elephant relative) 
  Cuvieronius, as well as ground sloths, toxodontids, and glyptodonts. The 
  concept of evolutionary anachronisms/megafaunal dispersal syndrome has been 
  criticised by some authors, who note that many large fruit are readily 
  dispersed by non-megafaunal animals, with it being noted that living agoutis 
  disperse avocado seeds, with spectacled bears have also having been observed 
  eating domestic avocados.

https://en.wikipedia.org/wiki/Avocado

TaurenHunter• 1 year ago

https://link.springer.com/article/10.1007/BF02904012

Early wild avocado seeds were smaller at around 2cm/.8in in diameter.

tim333• 1 year ago

Glossotherium robustum looks quite chunky. There's a skeleton of one in the Natural History Museum London https://en.wikipedia.org/wiki/Glossotherium

and an artists impression https://static.wikia.nocookie.net/fossil/images/9/95/Reconst...

ggm• 1 year ago

Bruce Chatwin mentions the tunnels and sloths in his book "in Patagonia" 1977

bell-cot3• 1 year ago

The longest described so far is in Pará state in the Amazon region, with combined internal galleries some 1,500 metres long ...

I'm not a Mining Engineer, to know when CO2 accumulation would become a problem (if the giant sloths were living in the tunnels). But the effort needed to manually remove the tailings from a tunnel is O(n^2) - because the working face keeps getting further from the exit.

So as the article asks - how could the effort needed possibly be worthwhile?

cess11• 1 year ago

How would the animal determine that the effort is no longer worthwhile?

bell-cot3• 1 year ago

I don't know. But pretty much every burrowing animal has to decide when the RoI has gotten too low to keep digging.

Qem3• 1 year ago

It appears to be combined lenght for the whole tunnel complex. Not 1,500 meters to the nearest exit.

rdtsc• 1 year ago

Dig slightly up so CO2 doesn’t accumulate in low areas and spread the tunnels around like a tree or a mesh? Work with your fellow sloth team, take turns, dilly-dally around. What else would sloths do ;-)

mmooss2• 1 year ago

The article at its source, Nature, with many more photos and a different title:

"Did giant ice age beasts carve these vast caves in South America?"

https://www.nature.com/articles/d41586-025-00216-x

veunes2• 1 year ago

The sheer size of these tunnels is mind-blowing

_dain_2• 1 year ago

god I wish I could live in tunnels. like a hobbit. these sloths had it all figured out ...

Chris2048• 1 year ago

What's stoppin' ya?

fc417fc802• 1 year ago

In most of the western world it's illegal to excavate any significant volume without a bunch of permitting and oversight. Additional regulations surrounding living spaces. Plus the fact that you don't generally own the volume underneath your lot in the first place.

If you make it past all that (regardless of whether you selected the legal or illegal route) there's the expense of doing so safely. Then add on the expense of maintenance (by which I mostly mean water management).

_dain_2• 1 year ago

government, money, local geology.

lmm• 1 year ago

https://discover.hubpages.com/living/The-Pitfalls-of-an-Unde... gets posted here every so often.

SamBam• 1 year ago

So not the Shrike?

beacon294• 1 year ago

I think they were carved by "the builders"...

caycep• 1 year ago

the irony is if it was some Stone Age counterpart to Seymour Cray

driggs• 1 year ago

Indeed, similar megafauna were present in North America as well. The West Virginia state fossil is Megalonyx jeffersonii, a giant ground sloth present until the end of the Pleistocene. They're estimated to have been 10 feet "tall" and to weight roughly a ton. Fossil bones were discovered in Haynes Cave, Monroe County near the present day Virginia border, and the species is named for Thomas Jefferson, who examined bones and authored the paper that identified this genus. (Though the history of exactly which bones he identified is slightly murky.)

https://en.wikipedia.org/wiki/Megalonyx

It seems likely that they were using these limestone caves for shelter, though it is also not uncommon for other Pleistocene fossils to be found and preserved in caves after washing in as sediment. I've never seen claw marks on cave walls quite large enough to attribute it to a ground sloth, but there are occasionally very large claw marks on cave walls... and I wouldn't want to be trapped in the dark with whatever creature left them behind.

emilfihlman• 1 year ago

Since no one has said, but I strongly feel like it should be said and it's so great and positive abd triggers many memories.

Secret tunnel!

zkmon• 1 year ago

Carving could have been done by natural processes, instead of creatures? Many large caves are created by simple process of chemical reactions and water flow over time. Any scratches on the surface could be from creatures.

veunes2• 1 year ago

From what I've read, these burrows have distinct claw marks ("claw-like markings on the walls") and structural patterns that don't match typical natural cave formation processes

perlcommunity• 1 year ago

okay badger moles

whatamidoingyo• 1 year ago

I visited MOAS in Daytona last week, and learned about the ground sloth for the first time in my life. Fascinating. I thought I knew just about every animal to have lived on earth, but I was so wrong. Curious what other creatures like this I don't know about.

Who carved South America's mysterious ancient tunnels? [pdf]

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