The South Dakota Badlands has been a treasure-trove for archeologists. Numerous artifacts dating from 380 BC to 1650 AD have been unearthed at almost 300 sites. The largest collection was found around the Pinnacle Point area. Paleontologists have been equally excited by the plethora of fossils uncovered in the park. Their discoveries have chronicled animal and plant life going back millions of years. Among the 50 extinct animal species found are three-toed horses (Mesohippus), hornless rhinoceroses (Subhyracodon), massive thunder beasts (Brontothere) and saber-toothed cats (Hoplophoneus). A very common creature was the sheep-sized Oreodont that lived here 40 million to five million years ago.