A “perforated (frill) lizard” from Late Cretaceous Montana to Texas, USA; and Canada.

The name is based on Greek toreo, “pierce, perforate”, a reference to the posterior crest, which is perforated by a pair of large openings, according to the nomenclator, Othniel Charles Marsh.

He explained that the name provides no basis for interpreting Torosaurus as “piercing lizard” because of its horns nor as “bulging lizard” from Latin torus, “a bulge”. The non-classical Spanish word toro, “bull” is not the correct derivation of the name. Named by paleontologist Othniel Charles Marsh (1831-1899) in 1891.