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Yizhousaurus sunae skull and jaw

Skull diagram showing the known material of Aardonyx. Based on photographs and measurements in original description and supplementary material. Scale bar = 10 cm

Photographs of the skull of BP/1/4779. (A) Right lateral view. (B) Dorsal view. (C) Left lateral view. Scale bar represents 10 mm. Photographs by Kimberley E.J. Chapelle.

Skull of the new basal sauropodomorph Leyesaurus marayensis (PVSJ 706). Photograph of the skull (A) and interpretative drawing (B) in lateral view. Dark grey color represents matrix and light grey color represents foraminae. Abbreviations: a, angular; aoF, antorbital fenestra; aoFo; antorbital fossa; Apmx, ascending process of the maxilla; d, dentary; f, frontal; itF, infratemporal fenestra; j, jugal; l, lacrimal; laoFo; lacrimal antorbital fossa; mF, mandibular fenestra; mx, maxilla; n, nasal; O, orbit; p, parietal; pf, prefrontal; pm, premaxilla; po, postorbital; rug, platform-like rugosities; q, quadrate; qj, quadratejugal; Rmx, ridge of the ascending process of the maxilla; sa, surangular; snf, subnarial foramen. Scale bar equals 1cm.

Photograph of the skulls NHMD 164741 and NHMD 164758. (A) NHMD 164741 in left lateral view. (B) NHMD 164758 in left lateral view.

Three-dimensional skull of BMT 1955.G35.1, Protoichthyosaurus prostaxalis. (B) Skull in left lateral view, as reconstructed in 2015. (C) Skull in right lateral view, as reconstructed in 2015. Note the distinctive asymmetric maxilla with long, narrow anterior process. Teeth are not in their original positions. Scale bar represents 20 cm.

Skull of Megacephalosaurus eulerti FHSM VP-321 in dorsal and palatal view. Right mandible in medial and lateral views.

Holotype skull of Plesiotylosaurus crassidens (LACM 2759) on display at the Natural History Museum of Los Angeles County.

Selmasaurus johnsoni mounted skull in the Rocky Mountain Dinosaur Resource Center in Woodland Park, Colorado

Cast of the skull of Parapsicephalus purdoni (specimen AMNH 1694) in the American Museum of Natural History.

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.

Skull cast of Liaoceratops yanzigouensis on display at the Baoding Natural History Museum.

Skeleton of Yamaceratops dorngobiensis (MPC-D 100/553) in right dorsolateral view. (A) Photograph; (B) Interpretive drawing. Bones are bounded by solid lines and colored beige; the matrix is gray. Shaded areas represent the broken surface of bones. Abbreviations: cd, caudal vertebrae; dr, dorsal ribs; dv, dorsal vertebrae; f, femur; fi, fibula; h, humerus; L, bone on the left side; p, isolated parietal; pp, pedal phalanges; R, bone on the right side; ra, radius; sk, skull; sv, sacral vertebrae; ti, tibia; u, ulna; il, ilium; is, ischium.

Skeletal elements of Lophorhothon atopus. (A, B and C) Partial skull roof and braincase (holotype FMNH 27383) in dorsal, ventral, and left lateral views. (D) Partial left nasal of FMNH 27383 in lateral view. (E) Left prefrontal of FMNH 27383 in lateral view. (F) Partial left jugal of FMNH 27383 in medial view. (G) Detail of marginal denticles of the dentary tooth in (H). (H) Apical half of a dentary tooth crown AUMP 2295 in lingual view. (I) Maxillary tooth crown of FMNH 27383 in labial view. (J) Left pubis of AUMP 2295 in lateral view. (K) Iliac process of the left ilium of FMNH 27383 in lateral view.

The skull of the holotype of Acristavus, MOR 1155

Holotype skull of Augustynolophus morrisi (LACM 2852) on display at the Natural History Museum of Los Angeles County.