For a while I have been trying to figure out exactly how many species of Triceratops are there. This is what I have figured out.
T. horridus horridus*
T. horridus flabellatus*
T. elatus ¤
T. elatus elatus* ¤
T. elatus obtusus* ¤
T. eurycephalus •
T. albertensis °
T. alticornis °
T. galeus °
T. ingens °
T. maximus °
T. sulcatus °
*=Subspecies are hypothetical. Those figuered here are specimens that seem to show enough differences in skull features to place them in some kind of grouping other than individual (I have considered sexual dimorphism and age here).
¤=Triceratops elatus has been placed by many under T. horridus. This species seems to show natural reduction in the size of the nasal horn core, therefore, I placed this here as a valid species along with its subspecies(T. elatus elatus [previously T. elatus and T. calicornis(intermediate between T. horridus horridus and T. elatus obtusus)] and T. elatus obtusus [previously T. obtusus].
•= T. eurycephalus is based on a poorly preserved skull, yet it may show some subgenaric differences(if not a dubious species. I might consider a new name (("Eurycephalia") [I came up with this name (it was emmended by T. Michael Keesey, thus, "Eurycephale") based on the species name which means "wide head" therefore("
°= These species are dubious, they may be synonymous with T. horridus horridus*, T. horridus flabellatus*, T. prorsus, T. elatus elatus* ¤, T. elatus obtusus* ¤, or T. ("Eurycephale") eurycephalus (If T. ("Eurycephale") eurycephalus is not a dubious species, that is) .
Note: "Eurycephale" Hanson, 2001 emend. Keesey was previously "Eurycephaila" Hanson, 2001