Shawnee legend tells of a herd of huge bison rampaging through the Ohio Valley, laying waste to all in their path. To protect the tribe, a deity slew these great beasts with lightning bolts, finally chasing the last giant buffalo into exile across the Wabash River, never to trouble the Shawnee again. The source of this legend was a peculiar salt lick in present-day northern Kentucky, where giant fossilized skeletons had for centuries lain undisturbed by the Shawnee and other natives of the region. In 1739, the first Europeans encountered this fossil site, which eventually came to be known...