Diceratops skull

Diceratops ( "two-horned face") Lull, 1905 is a ceratopsid herbivorous dinosaur genus from the Late Cretaceous period of North America. It is known only from a single poorly preserved skull described in 1905. For many years, it had been considered a variety of Triceratops, but recent analysis (Forster, 1996) suggests it is a distinct genus.

The paper that described Diceratops was originally part of O. C. Marsh's magnum opus, his Ceratopsidae monograph. Unfortunately, Marsh died (1899) before the work was completed, and John Bell Hatcher endeavored to complete the Triceratops section. However, he died of typhus in 1904 at the age of 42, leaving the paper still uncompleted. It fell to Richard Swann Lull to complete the monograph in 1905, publishing Hatcher's description of a skull separately and giving it the name Diceratops hatcheri.

Since the Diceratops paper had been written by Hatcher, and Lull had only contributed the name and published the paper after Hatcher's death, Lull was not quite as convinced of the distinctiveness of Diceratops, thinking it primarily pathological. By 1933, Lull had had second thoughts about Diceratops being a distinct genus and he put it in a subgenus of Triceratops: Triceratops (Diceratops), including T. obtusus; largely attributing its differences to being that of an aged individual.

The poorly preserved skull is the only fossil referred to Diceratops. Like Hatcher's other Triceratops skulls, it was found in eastern Wyoming. Superficially, it resembles that of Triceratops, but on closer examination, it is definitely odd: there is just a rounded stump where the nasal horn should be and the occipital (brow) horns stand almost vertically. Compared to other Triceratops skulls, it is slightly larger than average (2.0 m), but its face is rather short. There also are large holes in the frill, unlike other Triceratops skulls known. Some of these may be pathological, others seem to be genetic. Several authors have suggested that Diceratops may be directly ancestral to Triceratops, or perhaps its nearest relative.


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