{This page is under contruction.}. Marginocephalia is group of advanced ornithichians, specifically ceropod neornithichians. It includes both the ceratopsia, and the pachycephalosauria, as well as perhaps heterodontosaurs. All three groups have been at least once said to be omnivorous, and this could be used as indication for heterodontosaurs being marginocephalians.
[Slideshow A(Pic one)(Basal Marginocephalians): [A = Heterodontosaurus tucki, the type of heterodontosauridae, which may o rmay not be marginocephalians. B = Goyocephale lattimorei, a basal pachycephalosaur, notable for it's long "fangs". C = Abrictosaurus consors, whose "fangs" are smaller then other heterodontosaurs. D = Tianyulong confuciusi, a form notalbe for it's integment (See below.). E = Chaoyangsaurus youngi, a basal ceratopsian, notable for large orbits, despite probably being adult. F = Liaoceratops yanzigouensis, a neoceratopsian (See below.).G = Yinlong downsi, again with "fangs". H = Auroraceratops rugosus, a robustly built ceratopsian. I = Archaeoceratops oshimai, a basal ceratopsian.]]
Groups[]
No currently known fomrs lie outside the two or three groups, aldo some forms have been placed in either pachycephalosauria or ceratopsia, differing from one analysis to another. Some of these are Micropachycephalosaurus and Stenopelix, which could be basal to the two groups.
Ceratopsia[]
The ceratopsians where a group of omnivorous forms, which can be bipeds, quadrapeds, or falcutalive quadrapeds depending on taxon. It is separated into the psittacosaurids, some other genera, and neoceratopsia. The neoceratopsia is the point where bipedalism was begining to be lost, with the
leptoceratopsids being falcualtive quadrapeds, and protoceratopsid (and Bagaceratpsids?) as well as ceratopsoids being fully quadrapedal. There is also a potential group, bagaceratopsids, but these are generally assumed to be part of protoceratopsidae. They, like other marginocephalians, are a laurasian group.
Pachycephalosauria[]
They are/where the other widely accepted marginocephalian group. They, like ceratopsians are classically assumed to be herbivores, but modern research indicates that they may indeed be omnivores. Modern research has also caused many other contrversies, such as: Dracorex/Stigimoloch/Pachycepahlosaurus ontogenetic stage theory, flat head/dome head ontogenetic theory, head butters or not ? , all within pachycephalosauridae ? , among others.
Heterodontosauridae[]
Unlike the others, these have a complicated classification. They have poped up all over ornithichia including the most basal position, basal cerapods, basal neoornithichians, the sister clade to neornithichia, and of course marginocephalians. They, like many basal marginocephalians, have "fangs", and have been suggested to be omnivorous.
Biology and anatomy[]
{This section is heavily under contruction.}.
Integment[]
Within theropoda, "feathers" are widespread, from true ones maniraptor(iforms?), to the filament of more basal celurosaurs, to the potential megalosaur Scruriomimus. Even pterosaurs have "pycnofibers", hair-like integment potentialy homogulous with feathers. But the other side of dinsauria, the ornithichians had no such thing, not as we knew. However, in 2002, a specimen of Psittacosaurus, a marginocephalian, was found with potential "quils". However, these where not very similar to feathers, and many assumed them to be different entirely. Then, in 2009, a new genus of heterodontosaur, Tianyulong, was found wiht not only quils, but "dino-fuzz" similar to the integment of some theropods. At least one of these was a marginocephalian, and the other might be.