Einiosaurus dinosaur. Computer artwork of a two tonne, 20 foot (6 metres) long Einiosaurus wandering in a forest during the Late Cretaceous period (around 65 to 100 million years ago), in what is now Montana in the United States. Einiosaurus is believed to have had a low, strongly forward-curving nasal horn resembling a can opener. Like the better known Triceratops, Einiosaurus was a Ceratopsid, a large four-legged plant-eating dinosaur characterized by beaks, rows of shearing teeth in the back of the jaw, and elaborate horns and frills.