Not long ago North America was host to saber tooth cats, camels, mammoths and lions. Among these now seemingly exotic creatures, was the distant relative of the elephant: the mastodon. This story is launched from a backyard pond in Hyde Park, New York, where the most recent mastodon site was discovered. With the cooperation of some of today's leading paleontologists, learn how the mastodon evolved, how it migrated out of Africa and how it survived in the North American forests for roughly 3.7 million years. We'll show how it differed from its more famous cousin, the mammoth and we'll explore the controversy among the major theories explaining how and why this keystone species disappeared.

• Stephen M. Kajiura