Who carved South America's mysterious ancient tunnels? [pdf]
clp.unesp.br
clp.unesp.br
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.
"Did giant ice age beasts carve these vast caves in South America?"
But who was really in charge?
Modern humans are .11 million year old, and we arrived to America .015 million years ago.
Bears aren’t afraid of being eaten, but they still dig dens because they’re warm in the winter.
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
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.
Early wild avocado seeds were smaller at around 2cm/.8in in diameter.
and an artists impression https://static.wikia.nocookie.net/fossil/images/9/95/Reconst...
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?
Secret tunnel!
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).