Good Old Boy #64

From here:

"In 1803, [Thomas] Jefferson purchased a slice of land from Napoleon. How much land? Honestly, neither the French nor Jefferson really knew. And neither knew what that land contained.

To begin the long task of finding out, Jefferson dispatched Meriwether Lewis and William Clark on their long expedition across the west. And while Jefferson was unsure of how far they'd be going, or what wonders they might find, there was one thing he had hopes they would see. Mastodons. A large mammal, covered in shaggy fur, ten feet tall at the shoulder, and a rather close relative of the modern elephant.

Why would a man as smart as Thomas Jefferson expect to find a fur-coated elephant still hiding in the parts of America that were not then well know? Because he'd seen the bones of mastodons and other large ice age creatures, and in his day, most people, no matter how bright, did not believe that it was possible for an Animal to go extinct. If mastodons were not to be found in the parts of the country settled by Europeans, then they must be somewhere else. Even several decades later many people did not accept the idea of extinction.

Extinction threatened the "great chain of being," which could not tolerate missing links. Like the inhabitants of Easter Island who cut down the the last tree in confidence that there had to be more trees, you know, somewhere, the people of Jefferson's America knew that mastodons were still out there. They were merely hiding."