When was the first sloth discovered

Jefferson's ground sloth first appeared during the second-last glaciation, perhaps years ago. The species lived in woodlands, probably browsing on leaves, twigs and perhaps nuts. All of the Yukon specimens are relatively small, suggesting a last interglacial age about years ago. Information gathered from the northernmost specimens implies that the species occupied a broad east-west range in northwestern North America during a warm phase of the Late Pleistocene Epoch.

This species is of historical as well as paleontological significance: Thomas Jefferson's lecture on Megalonyx "great claw" to the American Philosophical Society in marked the beginning of vertebrate paleontology in North America.

Appropriately, Megalonyx jeffersonii was named for him, the third president of the United States. The species became extinct about years ago.

Looking for photos? The Canadian Museum of Nature has thousands of unique images reflecting the diversity of the natural world—including the photos and illustrations here in our Natural History Notebooks. One species of ground sloth is named after Thomas Jefferson.

The future third president had a well-known interest in fossils, and a friend had sent him some bones that had been found in a cave in West Virginia. Jefferson first thought the bones belonged to a large lion and called it the "Great Claw," or Megalonyx, according to the Thomas Jefferson Encyclopedia.

In , as he was preparing a paper on the find for the American Philosophical Society, he saw an engraving of a sloth skeleton and realized that his fossil was similar and that his classification was wrong.

Later, Jefferson was credited with discovering the extinct sloth, which was named Megalonyx jeffersonii. The six modern species of sloths are all arboreal, so they are called tree sloths. These sloths are small-bodied and weigh less than 20 pounds. Many of their extinct relatives were much larger and lived on the ground.

Because of this, they are referred to as ground sloths. When the glaciers melted back some 12, years ago, a change in climate occurred. Many Ice Age mammals moved farther north, like the musk ox and reindeer, or they became extinct, like the mammoth. The Giant Ice Age Sloth,Megalonyx jeffersonii, the famed "Giant Claw" discovered by Thomas Jefferson, stood almost ten feet tall and weighed 2 to 3 tons, as much as a small elephant.