If paleontology serves a purpose, it is to remind us, again and again, that the current breadth of life on Earth is but a meager fraction of its former diversity. We have all, by now, become accustomed to the fleet-footed yales, the lumbering hmungos, the sumo-esque therizinosaurs, but as little as two million years ago there existed a group of herbivores completely unlike any seen today, for the most part.