Page "Triceratops" Paragraph 44

These findings, however, were contested a few years later by Catherine Forster, who reanalyzed Triceratops material more comprehensively and concluded that the remains fell into two species, T. horridus and T. prorsus, although the distinctive skull of T. (" Nedoceratops ") hatcheri differed enough to warrant a separate genus.

She found that T. horridus and several other species belonged together, and T. prorsus and T. brevicornus stood alone, and since there were many more specimens in the first group, she suggested that this meant the two groups were two species.

It is still possible to interpret the differences as representing a single species with sexual dimorphism.