Eremotherium, the species of giant ground sloth that we have on display in our Hall of Paleontology, roamed North America 20,000 years ago. Thomas Jefferson, the great statesman who celebrates his 274th birthday today, roamed North America 200 years ago. It may seem like a stretch to connect the two, but in fact it was Thomas Jefferson who identified the first giant sloth found in North America, a cousin of Eremotherium called Megalonyx.
Thomas Jefferson was not only a great politician, he was a paleontologist too. When traveling to Washington D.C. to take the oath of office as Vice President of the United States in 1797 he carried with him a wagon load of fossils to present to the American Philosophical Society, of which he would be elected president the same year. Those bones would turn out to belong to Megalonyx, the first giant ground sloth to be discovered in North America.
At that time though, Jefferson didn’t know it was a sloth. Megalonyx, the name coined by Jefferson for the creature, simply means “great claw”. The bones, which were sent to Jefferson by Colonel John Stewart of Greenbriar County (present day West Virginia) included partial arm and leg bones and some bones from the hand including three giant claws. Not much to go on… Taking into account those ferocious looking claws, Colonel Stewart suggested in his letter that the bones might belong to a giant lion, tiger or other big cat. Jefferson initially came to the same conclusion and described the remains as such in his correspondence with other members of the APH. However, it was later discovered that an animal similar to Megalonyx had already been described by George Cuvier from remains discovered in Paraguay. Cuvier had identified the animal as a relative of modern sloths, nothing like a big cat!
Take a look at the skeleton of Eremotherium in our Hall of Paleontology. Scary…? Well, Megalonyx would have looked much like it. Looking at those giant claws and big, wide jaws it kind of makes sense that Jefferson thought these animals were fierce carnivores, but their intimidating size and long claws actually allowed them to browse for low-hanging leaves in trees and their big teeth were designed for crushing rough plant material. In fact, the diet of giant ground sloths caused so much wear and tear that their teeth needed to continuously grow so that they didn’t wear away. They were mostly quadrapedal (walking on four legs), but they could stand on their hind legs to reach up for food.
Inspired by fossil discoveries, Jefferson believed that there may have been huge creatures still living in the western wilderness, and even instructed Lewis and Clark to look for giant sloths, mammoths and even camels during their exploration of the Louisiana purchase. Unfortunately the Corps of Discovery and subsequent expeditions only served to prove that the mightiest beasts the New World had ever seen had already passed into history.