Megalonyx jeffersoni is the scientific name for Jefferson’s Giant Ground Sloth, a large herbivorous mammal that lived in North American during the Pleistocene (commonly called the “Ice Age”). Along with several other large mammal species (megafauna), it became extinct by 10,000 years ago, at the end of the Pleistocene. The genus name, Megalonyx, means great claw, and the species name, jeffersoni, was assigned in honor of our 3rd president, Thomas Jefferson, because he presented (at the American Philosophical Society meeting in 1797) the first scientific description of bones of a great clawed animal found in a Virginia cave. He did not recognize that the animal was a ground sloth; he thought that it was a large cat, like a lion. In 1822, Jefferson’s specimens were given the scientific name, Megalonyx jeffersoni.