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Re: Ornithopoda + (Heterodontosauridae + Marginocephalia) phylogeny
Tom Holtz wrote:
Can't say I much like a Neornithopoda that doesn't necessarily include
Camptosaurus, Iguanodon, and the hadrosaurids (i.e., the critters for whom
the clade was originally coined), but it isn't explicitly defined here.
Frankly, I can't think of a *less* appropriate name for a
Heterodontosauridae + Marginocephalia clade than "Neornithopoda". It
reminds me of one of Kurochkin's classifications of Aves, which proposed the
name "Euornithes" for a clade of enantiornithine birds. Very peculiar. It
reminds me of another pet peeve of mine in archosaurian systematics: having
the Suchia (crocodiles &c) as a clade within the Pseudosuchia.
Anyway, back to the proposed Heterodontosauridae + Marginocephalia clade.
One course of action would be to define a node-based Heterodontosauria as
"all descendents of the most recent common ancestor of _Heterodontosaurus_,
_Triceratops_, and _Pachycephalosaurus_". If heterodontosaurids are
ornithopods, then Heterodontosauria would become a heterodefinitional junior
synonym of Cerapoda. If heterodontosaurids are linked to marginocephalians
to the exclusion of ornithopods, then Heterodontosauria comprises
Heterodontosauridae + Marginocephalia.
However, I don't know how Ornithopoda is defined - is it stem-based or
node-based, and if node-based is _Heterodontosaurus_ one of the anchor
taxa? If it is, and Heterodontosauridae and Marginocephalia form a clade,
then pachies and ceratopsians would all become ornithopods. Looks like
another job for Mike... :-)
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