Fig 1.
Locality map: Grand Staircase-Escalante National Monument, southern Utah.
Map showing locality (indicated by star) of Machairoceratops cronusi gen et. sp nov. (UMNH VP 20550), recovered from the Wahweap Formation of Grand Staircase-Escalante National Monument (GSENM). GSENM is bounded by the red rectangle and silhouetted in dark gray on the inset of Utah and surrounding states (modified from [1]).
Fig 2.
Schematic Stratigraphic Section of the Wahweap Formation.
Schematic stratigraphic section of the Wahweap Formation within GSENM, southern Utah. Approximate stratigraphic positions of Machairoceratops cronusi (UMNH VP 20550) gen. et sp. nov. and Diabloceratops eatoni (UMNH VP 16699) indicated on the right of the column. Numbers to the right of the column represent dates obtained from radiometric dating of bentonite horizons and detrital zircons distributed discretely within the section (after [1–3]).
Fig 3.
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.
Fig 4.
Left squamosal of Machairoceratops cronusi (UMNH VP 20550) gen. et sp. nov.
Machairoceratops squamosal in lateral (A), medial (B), and caudal (C) views. Abbreviations: jp, jugal process; on, otic notch; pog, paroccipital groove; pop, postorbital process. Scale bar = 10 cm.
Fig 5.
Parietal of Machairoceratops cronusi (UMNH VP 20550) gen. et sp. nov.
Machairoceratops parietal complex in dorsal (A), right-lateral (B), rostral (C), and close-up caudal (D) views. D highlights the autapomorphic posteromedially-oriented sulcus. Abbreviations: em, midline embayment; lpr, lateral parietal ramus (r = right, l = left); mb, median bar; pf, parietal fenestra; p1, epiparietal locus p1 (r = right, l = left); ps, posteromedial sulcus, tb, transverse bar, vs, vascular sulcus. Scale bars = 10 cm.
Fig 6.
Braincase Machairoceratops cronusi (UMNH VP 20550) gen. et sp. nov.
Machairoceratops braincase in occipital (A) and left-lateral (B) views, with corresponding line drawings in occipital (C) and left-lateral (D) views. Abbreviations: boc, basioccipital; bpt, basipterygoid process (r = right, l = left); cc, carotid canal; CN II, optic canal; CN V, trigeminal foramen; fm, foramen magnum; lsb, laterosphenoid buttress (r = right, l = left); oc, occipital condyle; poc, paroccipital process. Scale bar = 10 cm.
Fig 7.
Evolutionary Relationships of Machairoceratops cronusi (UMNH VP 20550) gen. et sp. nov.
Results of the maximum parsimony and Bayesian phylogenetic analyses. Strict consensus of 1194 most parsimonious trees (tree length = 160, CI = 0.675, RI, 0.818, RCI = 0.552) of an analysis of 101 characters arrayed across 26 ceratopsian taxa (A). Numbers in node boxes indicate Bremer support indices to the left and bootstrap proportions presented as Groups Present/Contradicted (GC) values to the right. Resultant time-calibrated Bayesian topology (i.e., majority rule consensus tree of all sampled trees) from the morphological clock model with posterior probabilities at each node (B). Abbreviations: ALB, Albian; APT, Aptian, BRM, Barremian; CEN, Cenomanian; CMP, Campanian; CON, Coniacian; HAU, Hauterivian; MAA, Maastrichtian; Pmag, Paleomagnetism; RPC, Rapid Polarity Changes.