Mylodon darwinii: Darwin's ground sloth

Researchers have surface scanned the lower part of the jaw belonging to Mylodon darwinii and released the digital specimen to celebrate Charles Darwin's 210th birthday.

Mylodon darwinii is the scientific name for a species of extinct giant ground sloth. On finding the specimen, Darwin identified it as belonging to the same family as the modern sloths. Richard Owen later described it as a new species, and named it in honour of its discoverer. 

Mylodon lived during the Pleistocene epoch, between 1.8 million years and 12,000 years ago. The remains of the animal have been found throughout South America, from Bolivia in the north to southern Patagonia. This shows the animal was able to adapt to cold climates.

Mylodon darwinii weighed between 1,000 and 2,000 kilogrammes, and was about three metres long.

Like other sloths, it was vegetarian. But unlike some of its relatives, it did not burrow or climb trees.

The exact causes of its extinction are not fully understood, although climate change and its effects on vegetation were almost certainly partly responsible.

Mylodon after Darwin

Mylodon darwinii is best known from exceptionally well-preserved remains found at the end of the nineteenth century in a cave in southern Chile, now known as Mylodon cave. The remains include pieces of skin, fur and dung. Some of these are on display at the Museum.

These remains can tell us what Mylodon darwinii ate, and give us accurate radiocarbon dating. 

Small pieces of bone were embedded in the skin and were probably a defence against predators. Nonetheless, some bones of Mylodon darwinii show evidence of tooth marks, probably made by jaguars.

Explore Mylodon darwinii online

The Mylodon darwinii 3D models join those of the Toxodon and Megatherium specimens in the Darwin fossil mammals dataset on the Museum data portal. They are also available to view on Sketchfab, a 3D modelling platform.

These fossil mammals collected by Darwin are historically and scientifically important, but also very fragile. Access to these specimens has been restricted in the past, to protect the specimens from further damage.

By creating and openly releasing digital versions of Darwin's fossils on the Museum's data portal, we hope to increase access and use of the specimens online. 

The previously released Toxodon and Megatherium models have been viewed thousands of times, downloaded and printed all over the world. They have been used in engagement activities in the Museum and elsewhere including by researchers at in the Western Science Centre in California, the United States, during talks to English Heritage at Down House and at the Chilean Congress of Palaeontology.