Monday, June 19, 2017

Machairoceratops cronusi by Fabrizio De Rossi, 2016

Machairoceratops is a genus of centrosaurine ceratopsian dinosaur known from the Late Cretaceous Wahweap Formation (late Campanian stage) of Grand Staircase-Escalante National Monument, southern Utah, United States.

It contains a single species, M. cronusi, first described and named in 2016 by Eric K. Lund, Patrick M. O’Connor, Mark A. Loewen and Zubair A. Jinnah. The generic name is derived from Greek machairis, meaning “bent sword”, in reference to its unique frill ornamentation showing two forward curving horns on the frill’s uppermost part, and Latinized Greek ceratops, meaning “horned-face”, which is a common suffix for ceratopsian genera names. The specific name cronusi refers to Cronus, a Greek god who deposed his father Uranus by castrating him with a sickle or scythe based on the mythology, and as such is shown carrying a curved bladed weapon. Machairoceratops is known solely from the holotype UMNH VP 20550, found in 2006, which is housed at the Natural History Museum of Utah. It is represented by a partial skull including two curved and elongate eyesocket horncores, the left jugal bone, a nearly complete but slightly deformed braincase, the left squamosal bone, and a parietal bone complex and its unique horn ornamentation, all collected in association.

Holotype cranial Material and Cranial Reconstruction of Machairoceratops cronusi (UMNH VP 20550) gen. et sp. nov. Recovered cranial elements of Machairoceratops in right-lateral view, shown overlain on a ghosted cranial reconstruction (A). The jugal, squamosal and braincase are all photo-reversed for reconstruction purposes. Machairoceratops cranial reconstruction in dorsal (B), and right-lateral (C) views. Green circle overlain on the ventral apex of the jugal highlights the size of the epijugal contact scar (ejcs). Abbreviations: BC, braincase; boc, basioccipital; bpt, basipterygoid process; ej, epijugal; ejcs, epijugal contact scar; j, jugal; lpr, lateral parietal ramus; lsb, laterosphenoid buttress; m, maxilla; n, nasal; o, orbit, oc, occipital condyle; oh, orbital horn; on, otic notch; p, parietal; pf, parietal fenestra; pm, premaxilla; po, postorbital; poc, paroccipital process; p1, epiparietal locus p1; sq, squamosal. Scale bars = 0.5 m. Eric K. Lund, Patrick M. O’Connor, Mark A. Loewen, Zubair A. Jinnah