Lewis and Clark's Travels Included Dozens of Astonishing Animal Encounters

Meriwether Lewis and William Clark are known as trailblazing explorers of the American West, not pioneering scientists. But during their 8,000-mile journey from Missouri to the Pacific Ocean and back between 1804-1806, Lewis and Clark discovered 122 animal species, including iconic American animals like the grizzly bear, coyote, prairie dog and bighorn sheep.

When President Thomas Jefferson first charged his assistant Lewis with the mission of finding a passable river route to the Pacific, he included an assignment to “[observe] the animals of the country generally, & especially those not known in the U.S. the remains and accounts of any which may [be] deemed rare or extinct.”

Jefferson was especially enticed by fossils recovered of mastodons and a type of giant land sloth he dubbed the megalonyx (“big claw”). Unsure of what species the men would encounter in the wilds beyond Missouri, Lewis took crash courses in botany, zoology and specimen collection and preservation from the best scientific minds in Philadelphia.