Arrhinoceratops (meaning “no nose-horn face”) is a genus of ceratopsian dinosaur. The name was coined as its original describer concluded it had no nose-horn, however further analysis revealed this not to be the case. It lived during the early Maastrichtian stage of the Late Cretaceous, predating its famous relative Triceratops by a few million years, although it was contemporary with Anchiceratops. Its remains have been found in Canada. Described by W. A. Parks in 1925, Arrhinoceratops is known from a partially crushed, slightly distorted skull which lacked a lower jaw. The remains were collected from the Horseshoe Canyon Formation deposits along the Red Deer River in Alberta by a 1923 expedition from the University of Toronto.
Only one species is described, A. brachyops. Other material from Utah, named by Gilmore in 1946, was originally known as A. utahensis, thence transferred to Torosaurus. Arrhinoceratops belonged to the Ceratopsinae (previously known as Chasmosaurinae) within the Ceratopsia (the name is Ancient Greek for “horned face”), a group of herbivorous dinosaurs with parrot-like beaks which thrived in North America and Asia during the Cretaceous Period, which ended roughly 65 million years ago. It appears to be closely related to Torosaurus. Since this dinosaur is known only from its skull, scientists know little about its over-all anatomy. The skull features a broad neck frill with two oval shaped openings. Its brow horns were moderately long, but its nose horn was shorter and blunter than most Ceratopsians. Its body is assumed to be typical of the Ceratopsians, and based on the skull it is estimated to be 6 m (20 ft) long when fully grown.Arrhinoceratops, like all Ceratopsians, was a herbivore. During the Cretaceous, flowering plants were “geographically limited on the landscape”, and so it is likely that this dinosaur fed on the predominant plants of the era: ferns, cycads and conifers. It would have used its sharp Ceratopsian beak to bite off the leaves or needles.