The elephant-sized Megatherium was a giant ground sloth that once roamed South America.

Nature · Published 30 September 2026 Swipe more like this →

In short: Long before modern sloths hung from trees, the Megatherium walked the earth as a massive, four-tonne beast. This extinct genus, first identified by Georges Cuvier in 1796, could stand on its hind legs to reach high foliage, using a prehensile lip to feed before vanishing around 12,000 years ago.

The Megatherium, or 'great beast,' was a titan of the South American landscape. Its most famous species, Megatherium americanum, reached lengths of six metres and weighed up to 4,000 kilograms, rivaling the size of an Asian elephant. Unlike its modern, slow-moving tree-dwelling relatives, this ground sloth possessed a robust skeletal structure that allowed it to adopt a bipedal stance, bracing against trees to forage for leaves and twigs with a specialized, prehensile upper lip.

First discovered in 1787 along the Luján River in Argentina, the specimen was sent to Madrid before catching the eye of Georges Cuvier in Paris. Cuvier, a pioneer of comparative anatomy, correctly identified the fossils as a giant, extinct sloth. His work, published in 1796, marked a milestone in paleontology as one of the first prehistoric animals to receive a formal scientific name. Later research, including isotopic analysis, confirmed that these creatures were strictly herbivorous, though they lived in diverse temperate and arid environments.

The extinction of Megatherium remains a subject of intense study. Disappearing around 12,000 years ago, its decline coincided with the arrival of humans in the Americas. Archaeological sites like Campo Laborde in Argentina provide evidence of human interaction, showing that these massive animals were occasionally hunted and butchered. While climate change and habitat fragmentation likely played roles, the combination of human pressure and environmental shifts remains the most widely cited explanation for the end of these giants.

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