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Defining Ornithischia (was Re:)
Some authors would further expand/subdivide
Ornithischia. For example, in two issues of the
popular magazine Prehistoric Times (Issues # 80 and #
David Peters has written articles where he groups
*Lotosaurus*, *Effigia*, *Sacisaurus* and *Silesaurus*
together as a subclade within Ornithischia. Mr.
Peters coins the term "Paraornithischia" for this
subclade. Mr. Peters defines "Paraornithischia" as
ornithischians which possess a predentary bone, but do
not have retroverted pubes.
--- Tim Williams <email@example.com> wrote:
> Nick Gardner wrote:
> >And as usual, no one really seems to give a damn
> about Ornithischia,
> Hey I do!
> >A very basic model of the current understanding of
> >groups would probably be something like the
> >Ankylosauria (your "armored dinosaurs")
> >Ornithopoda (this would include your "duckbilled
> dinosaurs" and
> >"iguanodons", as well as lots of other taxa which
> are serially closer
> >to them)
> >Pachycephalosauria (this would be your "boneheaded
> >Ceratopsia (this would be your "horned dinosaurs")
> >Of course, this doesn't take into account forms
> that do not fall into
> >these groups, like basal thyreophorans (such as
> Scutellosaurus) and
> >basal ornithischians like Pisanosaurus or
> And now _Eocursor_.
> According to one recent phylogeny, the "basal
> ornithischian" category may be
> even broader. Many taxa that used to be regarded as
> ornithopods (but not _Hypsilophodon_ itself) might
> in fact be basal
> ornithischians, as non-cerapodan neornithischians.
> To complicate things even further (and I know this
> is not news to Nick), the
> heterodontosaurids could be basal ornithischians,
> basal cerapods, basal
> ornithopods, or basal marginocephalians (or
> heterodontosauriforms). They're
> a weird bunch.
> >It's important to understand that most researchers
> don't just split
> >groups into the old Linnean ranks anymore,
> Praise the Lord for that.
> Discover sweet stuff waiting for you at the
> Messenger Cafe. Claim your
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- From: Tim Williams <firstname.lastname@example.org>