During the famous Charles Darwin show trip on the HMS Beagle between 1831 and 1836 he sailed around the world and often set foot on dry land to collect samples and take note of flora and fauna – beginning his work as the Beagle resident naturalist at only 22 years old. These stops included various locations in South America including Argentina, Uruguay and, of course, the Galapagos Islands.
To his fortune, full of eccentric mammals evolved isolated in South America, since the continent separated from West Antarctica about 30 million years ago and only joined North America when a land bridge form about 3 million years ago. By observing these wonders for himself, Darwin pocketed thousands of specimens. His assemblage of fossils and rocks, as well as animal and plant samples, included those from 13 species of mammals.
He then passed on the objects and observations to a group of naturalists, including biologist Richard Owen, who identified several new species and helped trigger important discourse on natural selection and evolution. Today there are around 100 mammal bones and fragments from Darwin’s voyage, and they range between 10,000 and 500,000 years ago. Centuries later, researchers are still grappling with the complex evolutionary histories of these unusual mammals.
An 1880 illustration from The Natural History of Animals. (Credit: Igor Golovniov / Shutterstock)
Darwin’s findings included fossils of a glyptodon, a relative armadillos today covered with a shell of bone armor. The animals have puzzled evolutionary biologists because they have uniquely adapted skeletons and differ significantly from other species within their order. The Glyptodon doedicurus species brandished a sharp tail, which probably served as a fierce weapon.
Glyptodonts evolved about 35 million years ago in South America, and gradually seemed ball in size before their extinction at the end of the last ice age. One species was considered medium in size in the Miocene, at around 180 pounds, but a particularly hardy variety reached over 4,000 pounds in the Pleistocene.
Giant land sloths
A modern reconstruction of the Megatherium (Credit: Catmando / Shutterstock)
The curious naturalist also met Megatherium and Mylodon darwinii, two giant land sloths. The first claims the Title of the largest bipedal mammal in existence. Megatherium grows to the size of an elephant as an adult, weighing around 6 tons (about the size of a small delivery truck). Darwin Point a Megatherium skull in a cliff in Argentina in 1832. The creature had been describe by a French anatomist in 1796, but scientists was missing significant specimens to inspect – until Darwin’s miraculous discovery. He even kept part of the skull at home, which was not mediatized until 2017.
He came across evidence of Mr. darwinii, later named by Owen in honor of Darwin, the same year. The sloth would have measured between about 2,000 and 4,000 pounds. A man nearly 13,000 years old Mr. darwinii bone fragment that jumped in a cave in southern Chile remained in great shape thanks to the cold and dry environment. Work on the bone fragment has suggested this Mr. darwinii diverged from modern two-toed sloths about 22 million years ago. They were herbivores, like their lazy parents, but did not climb trees or dig underground.
Mr. darwinii died about 10,000 years ago, and Megatherium disappeared about 12,000 years ago. Some paleontologists claim that human hunting has contributed significantly to the decline of giant land sloths and other South American megafauna, but others combat that it is mainly related to the climate.
A metal gomphothere structure by the artist Ricardo Breceda. (Credit: Noah Sauve / Shutterstock)
These ancestors of elephants may have cropped during the Miocene era in Africa about 22 million years ago. Gomphotheres made their way to South America (where Darwin met them), as well as North America and Eurasia, and dragged in swamps, forests and meadows. South American Gomphotheres are supposed to have faded away at the end of the Pleistocene or the beginning of the Holocene.
Like today’s elephants, Gomphotheres had defenses. They also shared with the elephants huge molar teeth which moved like a conveyor belt system (larger teeth are moved from the back of the mouth to replace grinders worn out throughout their life).
A 1913 restoration of T. platensis>. (Credit: Robert Bruce Horsfall / Wikipedia)
Darwin perceived this bizarre elephant-sized mammal with rodent teeth and the face of a manatee. For this reason, he called it “perhaps one of the strangest animals ever discovered”. The stunned geologist was one of the first to collect fossils from the Toxodon species called platensis. T. platensis Probably snatch on a diverse mix of foods like herbs and, surprisingly, lawyers.
It is only relatively recently that scientists determined this T. platensis likely shares a common ancestor with rhinos, horses, and tapirs, through analysis of bone collagen proteins. Like its modern giant parents, the creature was enormous – the Toxodon was thought weigh more than a ton, comparable African black rhino. And like the black rhino, he was probably pretty quick for his size.
The Toxodon presented himself to Darwin in the form of a skull in Uruguay, and he purchased for around $ 10.26 at today’s rate. Obviously, the price was worth it: Darwin claimed that the fossil was one of the most important finds on the trip to South America.
A 1913 reconstruction of the Macrauchenia patachonica
This particular mammal looked a bit like a camel and weighed between 850 and 1,100 lbs. Darwin find Macrauchenia remains in Patagonia in 1834 and struggled to decipher its mysterious origins and extinction.
One of the strangest features: the position of its nasal opening differed from that of the majority of mammals, which is usually found above the front teeth. In the Macrauchenia patachonic, the opening was located in the middle of the eye sockets. Like Darwin, Owen was also baffled and initially proposed a connection to the llamas which was later disproved. To its credit, it was difficult to understand with limited technology, as they do not have any living close relative.
It wasn’t until 2017 that we really got to know each other M. patachonica. Scientists examined mitochondrial DNA from a fossil unearthed in a cave in southern Chile and found that M. patachonica is Related to the surviving Perissodactyla group, which T. platensis is also related to. Like other long paleontological debates, this revelation came after 180 years of wrangling among scholars – unfortunately, too late to satisfy Darwin’s curiosity.