1. American Mastodon
National Museum of Natural History
In the summer of 2009, a team of excavation workers in central Indiana discovered the scattered remains of a Mastodon--the first significant megafauna mammal
(and, for that matter, the first significant prehistoric vertebrate) to be found in this state. That's not surprising, as Mastodons roamed much of North America during the Pleistocene
epoch. More about the American Mastodon
2. Various Brachiopods
Small, hard-shelled, marine-dwelling animals closely related to bivalves, brachiopods were even more numerous from 400 to 300 million years ago than they are today. The shells of Indiana's brachiopods, and other prehistoric marine creatures, constitute this state's famous Indiana Limestone, which is considered the highest-grade limestone quarried in the United States.
3. Various Crinoids
They're not quite as impressive as the ten-ton sauropods
found in neighboring states, but Indiana is known far and wide for its fossilized crinoids--small, sea-dwelling invertebrates vaguely reminiscent of starfish. Some species of crinoid still persist today, but these animals were especially common in the world's oceans about 400 million years ago.