During Charles Darwin’s famous trip on the HMS Beagle between 1831 and 1836, he sailed around the globe and often stepped on land to gather samples and take note of flora and fauna — starting his job as the Beagle’s resident naturalist at just 22 years old. These stops included various South American locales, including Argentina, Uruguay and, of course, the Galápagos Islands.
To his fortune, plenty of eccentric mammals evolved in isolation in South America, since the continent broke off from West Antarctica about 30 million years ago and only joined North America when a land bridge formed about 3 million years ago. As he observed those wonders for himself, Darwin pocketed thousands of specimens. His assemblage of fossils and rocks, along with animal and plant samples, included those of 13 mammal species.
He then passed the objects and observations on to a group of naturalists, including biologist Richard Owen, who designated several new species and helped spark important discourse around natural selection and evolution. Today, around 100 mammal bones and fragments remain from Darwin’s journey, and they range between 10,000 and 500,000 years old. Centuries later, researchers still grapple with these unusual mammals’ complex evolutionary histories.