Brontothere is an ancient mammal That roamed the area of Badlands National Park about 38-34 million years ago. Badlands brontotheres are also known as Megacerops coloradensis in scientific literature. Sometimes called “titanothere,” its name means “thunder beast,” referring to how a traveling herd of massive brontotheres may have sounded long ago, thundering through ancient environments.

Brontotheres found in the Badlands would have measured around 8 feet tall and 16 feet long, the size of a large rhino or small elephant today, but brontotheres began as only dog-sized animals in the early Eocene epoch. Over the next 20 million years of the Eocene, brontotheres became larger as they evolved and diversified. By the late Eocene, brontotheres reached the massive size we see in Badlands fossil brontotheres today.