QUICK FACTS
Name: Plains viscacha (Lagostomus maximus)
Where it lives: South America, from southern Bolivia and Paraguay to Argentina
What it eats: Grasses, shrubs, seeds, and even its own feces
Across the vast plains of southern South America, a chubby rodent reigns underground in a vibrant, hierarchical world. The plains viscacha, a stout cousin of the chinchilla, builds subterranean "cities" known as "vizcacheras," where up to 50 individuals live together. With tunnels reaching 10 feet (3 meters) deep, these complex networks of dark chambers and hidden entrances fascinated Charles Darwin during his 19th-century travels through the region.
