| Ornithischia | ||
| The Vertebrates | Marginocephalia |
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Abbreviated Dendrogram
Dinosauromorpha
├─┬─Theropoda
│ └─Sauropodomorpha
│
└─Ornithischia
├─Thyreophora
│ ├─Stegosauria
│ └─Ankylosauria
└─Cerapoda
├─Ornithopoda
│ ╞═Hypsilophodontidae
│ └─Hadrosauridae
└─┬─Heterodontosauridae
└─Marginocephalia
├─Pachycephalosauria
└─Ceratopsia
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Contents
Overview |
The Marginocephalia or "fringed heads" were a specialised group of Ornithischians defined by a small shelf or frill at the back of their skull. There are two main types, the dome heads and the horned dinosaurs, which evolved from a common ancestor during the early Cretaceous. With the exception of one or two questionable Gondwana forms, the group appears to be limited to Laurasia.
Marginocephalia: Stenopelix.
Early Cretaceous (perhaps much earlier) to Late Cretaceous of China & North America.
Cerapoda: Ornithopoda + * : Pachycephalosauria + Ceratopsia.
Narrow parietal shelf; post squamosal shelf; short post maxillary plate; vomers contact maxilla (maxillae meet on midline) rather than premaxilla; premaxillae excluded from internal nares; no obturator process on ischium; pubis short, with loss of pubic symphysis.
Links: DinoData: Marginocephalia; Introduction to the Marginocephalia; Marginocephalia - EnchantedLearning.com; New Page 6; The Natural History Museum's Dino Directory; Pachycephalosaurs and Ceratopsians (November 5). ATW011227.
checked ATW060107