Re: saropodomorph systematics

["T. Michael Keesey" <mightyodinn@yahoo.com>]

--- adam Yates <adam_m_yates@yahoo.co.uk> wrote:
> Dear Mike, I just read your comments of my paper in the archives of the DML.
> I'd just like to clarify one point that you raised. You asked wether
> "Vulcanodon + Eusauropoda" was intended to be a definition of Sauropoda.
> Absolutely not! It was just meant to be a clarification of the content that
> was intended when I used the name Sauropoda in that paper.

That was my suspicion.

> I was really
> trying to avoid PT in that paper because a) the phylocode has not yet been
> instituted, b) the results produced radically different contents of
> Prosauropoda and Sauropoda when Sereno's definitions were applied and to
> apply them would have resulted in convolted and confusing discussion and
> finally d) I really did not want to add to the proliferation of PT
> definitions before 200n.

Good points (what happened to 'c', though?...)

> However I use PT (and Sereno's definitions) in my
> subsequent papers (two in press). I have now seen much more Prosauropod
> material and I have changed many of the codings in the J. Syst. Palaeo paper.
> I now find a small (6 species with a handfull of maybes not included in the
> analyses), monophyletic Prosauropoda but a significant number of traditional
> prosauropods fall elsewhere (basal sauropods and basal sauropodomorphs).

Interesting -- so _Plateosaurus_ has some companions.

I'm trying to put together a phylogeny for the new version of the Dinosauricon.
I was going to base it primarily on the one from your _Thecodontosaurus_ paper,
but now ... maybe I should just do this:

--+--Saturnalia
  `--+--Thecodontosaurus
     `--+==HUGE POLYTOMY OF EVERYTHING
        `--+--Blikanasaurus
           `--Sauropoda sensu stricto

> Lastly there are some clades in Sauropodomorpha that desperately need naming
> (well I think they do because I'm always having to refer to them in my papers
> and it is damned inconvenient not having names for them). These are the node
> Sauropoda + Prosauropoda  OR (if you are happy to call this node
> Sauropodomorpha) the stem based 'total group' (ie. Saltasaurus <--
> Vultur/Passer/ whatever). At the moment I call these two Sauropodomorpha
> sensu stricto and Sauropodomorpha sensu lato.

IIRC, Olshevsky did propose a name for Prosauropoda + Sauropoda, back when he
placed Segnosauria in Sauropodomorpha (sensu lato). The name was Brontosauria
-- I once used it on The Dinosauricon for that node-based clade.

> The clade that contains all of
> the classic big, columnar-limbed sauropods (maybe defined as the most recent
> common ancestor of Vulcanodon, Kotasaurus, Isanosaurus and Saltasaurs) also
> needs a name. Multiple specifeiers are needed because the basal taxa are
> somewhat labile due to their fragmentary nature. Perhaps this is a situation
> where an apomorphy based definition would be superior especially since the
> need for a name stems from a need to discuss a group that is united by a
> distinctive, derived body plan.

Just what I was thinking. (There's also _Gongxianosaurus_ in the mix....)
Which apomorphy, though?

Using _Sauropoda_ for this clade would agree better with traditional usage.
"Sauropodiformes" is available for a clade within _Sauropodomorpha_, including
_Sauropoda_, whether it's the aforementioned node or the stem-sister to
_Prosauropoda_ sensu Wilson & Sereno ... just thinking out loud....

> cheersAdam YatesPS you can forward this to the
> DML if you wish.

Certainly -- thanks for the response.


=====
=====> T. Michael Keesey <keesey@bigfoot.com>
=====> The Dinosauricon <http://dinosauricon.com>
=====> BloodySteak <http://bloodysteak.com>
=====> Instant Messenger <Ric Blayze>
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