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Re: Aliwalia [from Adam Yates]
(Sorry for the cross-posting. Info for the PhyloCode mailing list:
- If you're pressed for time, please jump to the last paragraph.
- According to a new, unpublished analysis, the traditional Prosauropoda is
turned into a long list of successive outgroups to Sauropoda. Prosauropoda
has a stem-based definition with *Plateosaurus* as the internal specifier;
its sistergroup is Sauropoda, which used to consist of animals like the
*Brachiosaurus* shown in Jurassic Park; Sauropodomorpha is a stem-based
clade that includes both; against all expectations, *Plateosaurus* has
turned out to be among the most basal sauropodomorphs -- all previous
suggestions of prosauropod paraphyly had it rather close to the traditional
contents of Sauropoda.)
>Interesting that massospondylids, Yunnanosaurus and 'riojasaurids' have
>been moved to basal sauropod status in Yates' latest analyses though. I
>think that leaves plateosaurids as the only prosauropods (unless
>Efraasia's position has stabilized), presumably with Saturnalia and
>Thecodontosaurus still outside the Prosauropoda + Sauropoda clade.
If Prosauropoda is limited to plateosaurids (either completely or in
essence), I wonder if there's any point in keeping the term "Prosauropoda"
at all. Plateosauria or just Plateosauridae would probably be a better
term for this group, considering that the majority of taxa traditionally
placed in the Prosauropoda are now regarded as either basal
sauropodomorphs or basal sauropods. And the restricted composition of
Prosauropoda sensu stricto makes the name ("before sauropods") even more
inappropriate than it ever was. Just a thought...
In phylogenetic nomenclature this could be handled, for example, by defining
Plateosauridae as "everything closer to *Plateosaurus* than to
*Massospondylus*", and by registering it before Prosauropoda. So if
Prosauropoda became a junior heterodefinitional synonym of Plateosauridae,
Plateosauridae would have to be used as the valid name for the clade.
I fear we'll need to have a _large_ conference where people will work out a
finely crafted system of priority which would then need to be published in
the companion volume... The alternative is we'd have to live with a lot of
unpleasant names for unfamiliar contents, even with well thought-out
definitions. This issue is not trivial; in my limited experience it's one of
the most important reasons for opponents to the PhyloCode (...after
ignorance, that is...).