OLIGOCENE MAMMAL TEETH FROM THE BRULE FORMATION, SOUTH DAKOTA
The Brule prairies of the Oligocene Period were inhabited by tapirs, three toed horses, and rhinoceroses. In the nearby swamps there were large crocodiles and a pigmy hippopotamus. There were primitive oreodonts, creodonts, false saber tooth cats, and true saber tooth cats also roaming the Brule prairies at the same time as their Oregon counterparts, when several volcanoes in the United States erupted violently, catching the Brule and John Day beasts in choking volcanic ash. The modest collection of horse (mesohippus) and oreodont (merycoidodon) teeth and jaws displayed below are almost identical to some of the specimens found by paleontologists in the John Day Fossil Beds of Oregon.
Note: To zoom in and out, click on the photo below: