HPH 15 • Ornithischia

Order Ornithischia SEELEY 1888 ... 1
Suborder Ornithopoda MARSH 1871 ... 5
Family Pisanosauridae CASAMIQUELA 1967 ... 7
Family Heterodontosauridae KUHN 1966 ... 7
Family Hypsilophodontidae DOLLO 1882 ... 9
Family Iguanodontidae COPE 1869 ... 13
Family Hadrosauridae COPE 1869 ... 20
Subfamily Hadrosaurinae LAMBE 1918 ... 22
Subfamily Saurolophinae BROWN 1914 ... 28
Subfamily Cheneosaurinae LULL & WRIGHT 1942 ... 30
Subfamily Lambeosaurinae PARKS 1923 ... 32
Family Psittacosauridae OSBORN 1923 ... 37
Family Pachycephalosauridae STERNBERG 1945 ... 39
Suborder Stegosauria (MARSH 1877, order) ... 42
Family Stegosauridae MARSH 1880 ... 44
Subfamily Scelidosaurinae NOPCSA 1928 ... 44
Subfamily Stegosaurinae NOPCSA 1917 ... 45
Suborder Ankylosauria OSBORN 1923 ... 52
Family Acanthopholididae NOPCSA 1902 ... 54
Family Nodosauridae MARSH 1890 ... 57
Suborder Ceratopsia MARSH 1890 ... 62
Family Protoceratopsidae GRANGER & GREGORY 1923 ... 64
Family Ceratopsidae MARSH 1888 ... 67
Ornithischia incertae sedis ... 81
Bibliography ... 81
Index ... 82

Order Ornithischia SEELEY 1888 1

(Orthopoda COPE 1866, Predentata MARSH 1894, Praedentata HENNIG 1915, Dinosauria OWEN 1342 [in part],

Deinosauria WATSON 1957 [in part])

Herbivorous archosaurian reptiles characterised by the possession of a pelvic girdle with a basically avian configuration; although essenti ally bipedal they display a tendency towards the assumption of partial or total quadrupedalism.

Skull of variable size, proportions and construction. Premaxilla usually expanded terminally and displaying an extensive lateral development which excludes the shortened maxilla from the external naris and any contact with the nasal. Otic notch widely open and markedly overhung by the squamosal. One or two supraorbital bones are usually present, but the lacrimal and prefrontal are small and the postfrontal and postparietal elements have been lost. External nares separate and typically subterminal in position, cheek region and lateral surface of lower jaw concave, suggesting the presence of cheek pouches in life. Nasal bones elongate, in correlation with which both the frontals and the parietals are short. Jugal arching outward anteriorly from external surface of maxilla and in many cases developing a prominent descending flange. Quadrate generally tall and inclined forwards inferiorly, the jaw articulation being situated below the level of the tooth row. Quadratojugal typically small and sheathing the quadrate to only a limited degree. Occiput plate-like, with reduced post-temporal fenestrae and a persistent unossified gap between the parietals (which are generally fused) and the supraoccipital. Braincase longer and less deep than in Saurischia, with moderately developed basal tubera and basipterygoid processes. Palate generally high-vaulted and narrow anteriorly. The choanae tend to be displaced rearwards, the premaxillae being excluded from their margins by the maxillae. Palatal rami of pterygoids reduced in length but flaring widely laterally to appose each other in the mid-line and in some cases fuse, eliminating the interpterygoid vacuity. Epipterygoid apparently lost, palatal vacuities reduced or absent. Lower jaw terminated anteriorly by a predentary element. Maxillary and mandibular dentition forming variably developed batteries of grinding teeth which develop leaf-shaped crowns with bevelled triturating surfaces.

Presacral vertebrae numbering 24-34, including 9-15 cervicals and about 17 dorsals; sacral count varying from 4-11. Transverse processes of cervical region extending laterally rather than downward, those of the dorsals usually being angled strongly upward. Vertebrae little excavated, ossified tendons frequently present along neural spines of trunk and tail. Cervical ribs generally free…