Both the Fruita and Cleveland-Lloyd specimens were described by Madsen and Samuel Paul Welles in a 2000 monograph, with the Utah specimen being assigned to the new species "C. dentisulcatus" and the Colorado specimen to the new species "C. magnicornis". The name "dentisulcatus" refers to the parallel grooves present on the inner sides of the premaxillary teeth and the first three teeth of the lower jaw in that specimen; "magnicornis" points to the larger nasal horn. The validity of both species, however, was questioned in subsequent publications. Brooks Britt and colleagues, in 2000, claimed that the "C. nasicornis" holotype was in fact a juvenile individual, with the two larger species representing the adult state of a single species. Oliver Rauhut, in 2003, and Matthew Carrano and Scott Sampson, in 2008, considered the anatomical differences cited by Madsen and Welles to support these additional species to represent ontogenetic (age-related) or individual variation.