named by Thomas M. Lehman in 1990. The latter species, originally Monoclonius canadensis Lambe 1902, had been described as Eoceratops canadensis by Lambe in 1915. Eoceratops and the long-horned Chasmosaurus kaiseni were thought to probably be exemplars of Mojoceratops by Nicholas Longrich, although different teams of researchers have found Mojoceratops to be a synonym of Chasmosaurus russelli. Campbell and colleagues, in their 2016 analysis of Chasmosaurus specimens found Eoceratops and C. kaiseni to be referable to Chasmosaurus sp. due to the lack of the parietal preserved in the holotypes of both. Richard Swann Lull in 1933 named an unusual, short-muzzled skull, specimen ROM 839 (earlier ROM 5436) collected in 1926, as Chasmosaurus brevirostris, "with a short snout". This has been seen as a junior synonym of C. belli. Charles Mortram Sternberg added Chasmosaurus russelli in 1940, based on specimen NMC 8800 from southwestern Alberta (lower Dinosaur Park Formation). The specific name honours Loris Shano Russell. In 1987, Gregory S. Paul renamed Pentaceratops sternbergii into Chasmosaurus sternbergi, but this has found no acceptance. In 2000, George Olshevsky renamed Monoclonius recurvicornis Cope 1889 into Chasmosaurus recurvicornis as its fossil material is likely chasmosaurine; this is a nomen dubium. Thomas Lehman described Chasmosaurus mariscalensis in 1989 from Texas, which has now been renamed Agujaceratops. The most recently described species is Chasmosaurus irvinensis named in 2001, which stems from the uppermost beds of the Dinosaur Park Formation. This species was given its own genus, Vagaceratops, in 2010. However, Campbell et al. (2019) referred Vagaceratops back to Chasmosaurus. As Fowler and Fowler found Vagaceratops likely to be the sister taxon of Kosmoceratops in 2020, they suggested it should be maintained as a distinct genus from Chasmosaurus, as its placement would probably remain unstable until chasmosaurines are better understood. The species Mojoceratops perifania was based on holotype specimen TMP 1983.25.1 consisting of a partial skull including the parietal and from the paratypes TMP 1999.55.292, an isolated lateral ramus of a right parietal, and NMC 8803, central bar and lateral rami of parietals. Specimens AMNH 5656, NMC 34832 and TMP 1979.11.147, and (tentatively) AMNH 5401 and NMC 1254 were also referred to the genus. All specimens assigned to Mojoceratops were collected from the Dinosaur Park Formation (late Campanian, 76.5–75 ma) of the Belly River Group of Alberta and Saskatchewan, western Canada. Mojoceratops was named by Nicholas R. Longrich in 2010 and the type species is Mojoceratops perifania.