Brontotherium

What you're getting

Brontotherium's one of those prehistoric megafauna that paleontologists kept rediscovering and renaming — it's had four different names in total, including Megacerops, Brontops and Titanops. The scientific community's mostly moved on to Megacerops ("giant horned face") these days, but Brontotherium ("thunder beast") is the one that's stuck in the public imagination, and honestly, it's the better name.