Thomas Jefferson loved mastodons, in part because he wanted to prove that American animals were not degenerate. In the late 1700s a French naturalist, Georges-Louis Leclerc, Comte de Buffon, published a massive, multi-volume natural history called, appropriately Natural History. In it, Buffon outlined what he called his “theory of American degeneracy,” wherein he argued that all people and animals native to the Americas were, well, degenerate. This enraged Thomas Jefferson, who sought to prove Buffon wrong by finding evidence of American mastodons, an animal that the third president still believed was out there, somewhere, roaming the American west.
Below: Mastodon by paleo artist Charles Knight from 1897.