Palaeos		Ornithischia
Vertebrates		Marginocephalia

Ornithischia: Ceratopsia

DINOSAUROMORPHA
|--+--THEROPODA
|  `--SAUROPODOMORPHA
|
ORNITHISCHIA
|--Thyreophora
|  |--Stegosauria
|  `--Ankylosauria
`--Cerapoda
   |--Ornithopoda
   |  |==Hypsilophodontidae
   |  `--Hadrosauridae
   `--+--Heterodontosauridae 
      `--Marginocephalia 
         |--Pachycephalosauria 
         `--Ceratopsia 

1. Marginocephalia X

This page is being revised

Marginocephalia

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.

Descriptions

Marginocephalia: Stenopelix. 

Range: Early Cretaceous (perhaps much earlier) to Late Cretaceous of China & North America. 

Phylogeny: Cerapoda: Ornithopoda + * : Pachycephalosauria + Ceratopsia. 

Characters: 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.