Gigantic South American burrows point to giant ground sloths as builders
Researchers studying kilometre‑long tunnels across Brazil and Argentina argue they are palaeoburrows carved by giant ground sloths (such as Glossotherium and Scelidotherium) during the Early Cretaceous in Botucatu sandstone; the largest known burrow runs about 1.5 kilometres with claw‑marked ceilings, suggesting multiple animals over time, though the exact purpose remains debated.