[N] 2010 Diabloceratops eatoni
Kirkland, J.I. & DeBlieux, D.D., 2010, \\\\\\\"New basal centrosaurine ceratopsian skulls from the Wahweap Formation (Middle Campanian), Grand Staircase–Escalante National Monument, southern Utah\\\\\\\", In: Ryan, M.J., Chinnery-Allgeier, B.J., and Eberth, D.A. (eds.) New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, Bloomington, Indiana University Press, p. 117-140
Abstract: A new basal centrosaurine ceratopsid, Diabloceratops eatoni is described from the Wahweap Formation (lower to middle Campanian, Upper Cretaceous) of Grand Staircase-Escalante National Monument, southern Utah. The isolated, nearly complete skull is one of the oldest and is the first diagnosable centrosaurine recovered south of Montana. It shares with more derived centrosaurines a stepped squamosal and a nasalpremaxillary process along the caudal border of the naris.
The species may be diagnosed by numerous autapomorphies relative to other centrosaurines: the preorbital skull is deeper and shorter than other known ceratopsids,, rostral to a low, subconical nasal horn is a smaller \\\\\\\"epinasal\\\\\\\", a large accessory antorbital fenestra is present, fused frontals form a steep vault between large postorbital horns at level of palpebrals, elongate jugals expose the caudal end of maxillae in lateral view, large, triangular, vertically oriented, blade-like epijugal extends laterally from the jugal bone, the erect frill is widest at the laterally directed squamosals, tapering to half its width at the base of a pair of elongate caudal p arietal spines separated by a medial notch, epoccipitals on the lateral margin of parietal decrease in size caudally to base of parietal spines, and the parietal fenestrae are caudorostrally elongate.
The long postorbital horns and small narial horn are primitive character states for ceratopsids as indicated by the ceratopsid sister taxon Zuniceratops. The basal position of Diabloceratops among centrosaurines is supported by the ascending process of the premaxilla not contacting the lacrimal as in 3 other centrosaurines; rather it terminates rostrally to this element as in Zuniceratops and all chasmosaurines.
A second, larger partial centrosaurine skull recovered from the Wahweap Formation is not represented by enough critical elements to be confidently diagnosed. We tentatively placed it in the genus Diabloceratops based on the presence of long postorbital horns, and a dorsoventrally oriented attachment scar on the jugal bone, indicating the presence of a possibly similar blade-like epijugal. It can be distinguished from Diabloceratops eatoni in bearing epoccipitals closely appressed to either side of the squamosal-parietal suture.
The presence of a well-developed accessory antorbital fenestra in Diabloceratops is shared with its sister taxon Zuniceratops. Among more basal neoceratopsians, only Magnirostris and Bagaceratops share this distinct character. The presence of distinct, albeit tiny, postorbital horns, indicates that Magnirostris is the Asian sister taxon to North America’s larger ceratopsids.
The genus name combines the Spanish diablo, \\\\\\\"devil\\\\\\\", a reference to the horns on the neck shield, with a Latinised Greek ceratops, \\\\\\\"horn face\\\\\\\", a usual element in ceratopian names. The specific name honours paleontologist Jeffrey Eaton. The fossil, holotype UMNH VP 16699, was in 2002 found by DeBlieux in the Grand Staircase-Escalante National Monument and consists of a partial skull with a piece of the lower jaw.
Abstract: A new basal centrosaurine ceratopsid, Diabloceratops eatoni is described from the Wahweap Formation (lower to middle Campanian, Upper Cretaceous) of Grand Staircase-Escalante National Monument, southern Utah. The isolated, nearly complete skull is one of the oldest and is the first diagnosable centrosaurine recovered south of Montana. It shares with more derived centrosaurines a stepped squamosal and a nasalpremaxillary process along the caudal border of the naris.
The species may be diagnosed by numerous autapomorphies relative to other centrosaurines: the preorbital skull is deeper and shorter than other known ceratopsids,, rostral to a low, subconical nasal horn is a smaller \\\\\\\"epinasal\\\\\\\", a large accessory antorbital fenestra is present, fused frontals form a steep vault between large postorbital horns at level of palpebrals, elongate jugals expose the caudal end of maxillae in lateral view, large, triangular, vertically oriented, blade-like epijugal extends laterally from the jugal bone, the erect frill is widest at the laterally directed squamosals, tapering to half its width at the base of a pair of elongate caudal p arietal spines separated by a medial notch, epoccipitals on the lateral margin of parietal decrease in size caudally to base of parietal spines, and the parietal fenestrae are caudorostrally elongate.
The long postorbital horns and small narial horn are primitive character states for ceratopsids as indicated by the ceratopsid sister taxon Zuniceratops. The basal position of Diabloceratops among centrosaurines is supported by the ascending process of the premaxilla not contacting the lacrimal as in 3 other centrosaurines; rather it terminates rostrally to this element as in Zuniceratops and all chasmosaurines.
A second, larger partial centrosaurine skull recovered from the Wahweap Formation is not represented by enough critical elements to be confidently diagnosed. We tentatively placed it in the genus Diabloceratops based on the presence of long postorbital horns, and a dorsoventrally oriented attachment scar on the jugal bone, indicating the presence of a possibly similar blade-like epijugal. It can be distinguished from Diabloceratops eatoni in bearing epoccipitals closely appressed to either side of the squamosal-parietal suture.
The presence of a well-developed accessory antorbital fenestra in Diabloceratops is shared with its sister taxon Zuniceratops. Among more basal neoceratopsians, only Magnirostris and Bagaceratops share this distinct character. The presence of distinct, albeit tiny, postorbital horns, indicates that Magnirostris is the Asian sister taxon to North America’s larger ceratopsids.
The genus name combines the Spanish diablo, \\\\\\\"devil\\\\\\\", a reference to the horns on the neck shield, with a Latinised Greek ceratops, \\\\\\\"horn face\\\\\\\", a usual element in ceratopian names. The specific name honours paleontologist Jeffrey Eaton. The fossil, holotype UMNH VP 16699, was in 2002 found by DeBlieux in the Grand Staircase-Escalante National Monument and consists of a partial skull with a piece of the lower jaw.