Ceratopsidae

Collage of four ceratopsids, clockwise from top left: Titanoceratops, Styracosaurus, Triceratops and Utahceratops. These files are already on Commons with their respective licenses. This montage was made for the article Ceratopsidae on Wikipedia. File:Titanoceratops.jpg File:Torosaurus, is it? (20752673005).jpg File:Triceratops Skeleton Senckenberg.jpg File:Utahceratops gettyi 1 salt lake city.jpg

Collage of four ceratopsids, clockwise from top left: Titanoceratops, Styracosaurus, Triceratops and Utahceratops. These files are already on Commons with their respective licenses. This montage was made for the article Ceratopsidae on Wikipedia. File:Titanoceratops.jpg File:Torosaurus, is it? (20752673005).jpg File:Triceratops Skeleton Senckenberg.jpg File:Utahceratops gettyi 1 salt lake city.jpg

Menefeeceratops is a genus of ceratopsid dinosaur from the Menefee Formation in the United States. It is is believed to have been approximately 4 m long, and had two large horns above the eyes like other ceratopsians. Menefeeceratops was one of the earliest and most basal known members of the ceratopsids, and the oldest known centrosaurine. Its age and location was instrumental in helping to understand the evolution and diversification of the centrosaurine dinosaurs.

Locality map: Grand Staircase-Escalante National Monument, southern Utah. Map showing locality (indicated by star) of Nasutoceratops titusi holotype UMNH VP 16800, recovered from the Kaiparowits 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]). The original map has been modified to show Nasutoceratops instead of Machairoceratops as in the original source. New location based on map in Ceratopsid Dinosaurs from the Grand Staircase of Southern Utah, page 489.

Locality map: Grand Staircase-Escalante National Monument, southern Utah. Map showing locality (indicated by star) of Kosmoceratops richardsoni holotype UMNH VP 17000 and assigned subadult UMNH VP 16878, recovered from the Kaiparowits 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]). The original map has been modified to show Kosmoceratops instead of Machairoceratops as in the original source. New location based on map in Ceratopsid Dinosaurs from the Grand Staircase of Southern Utah, page 489.

Pectoral girdles and forelimbs of dinosaurs in left lateral view, depicting resting scapular and forelimb orientations in different dinosaurian groups as recommended according to the results of this study. In each case, solid horizontal line is parallel to long axis of sacrum. A. theropods without semilunate carpals (Dilophosaurus wetherilli, UCMP 37302). B. theropods with semilunate carpals other than Caudipteryx (Velociraptor mongoliensis, after reference [60]). C. Caudipteryx (C. sp., after reference [8]). D. ceratopsids (Styracosaurus albertensis, NMC 344). E. basal sauropodomorphs (Plateosaurus engelhardti, AMNH 6810). F. non-hadrosaurian ornithopods (Thescelosaurus neglectus, reference [62]). G. hadrosaurids (Parasaurolophus walkeri, after reference [48]). Angle labels: B = scapular orientation relative to long axis of sacrum. E = elbow angle. S = shoulder angle. W = wrist angle. See Materials and Methods section for descriptions of angles.

Achelousaurus horneri skull, collected in Glacier County, Montana, at the Museum of the Rockies in Bozeman, Montana. The Ceratopsidae are those dinosaurs with head frills. There are three large subgroups of Ceratopsidae: Centrosaurinae, Ceratopsinae, and Chasmosaurinae. The Triceratopsini are a "tribe" of the Chasmosaurinae -- a genus so vast that it gets the special name "tribe". The Pachyrhinosaurini are a "tribe" within the Centrosaurinae. Achelousaurus is a genus within the Pachyrhinosaurini. So far, only three skulls and some limited skeletal remains have been collected anywhere in the world -- and all of them in Montana. Their bony frills are quite similar to the Styracosaurus albertensis, although their other skull features (such as big bony bosses on the nose and behind the eyes) are not.