Geologist here! A fun fact that has received some previous discussion [1] here:

Some of these same missing megafauna (likely giant ground sloths) dug an impressive network of several-meter-diameter tunnels through the unusually stable, iron-rich soils of southern Brazil, which survive to this day [2].

You can actually go and walk through these burrows, despite the fact that the species who dug them are long-extinct.

[1] https://news.ycombinator.com/item?id=14014049

[2] https://www.discovermagazine.com/planet-earth/get-lost-in-me...