Wilson & Sereno's Sauropod Phylogeny

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

Received my copy of Wilson & Sereno's sauropod phylogeny monograph
yesterday: well worth the wait.  Great stuff, and a lot of interesting
information in there, as well as excellent illustrations (some new, some
from old Marsh lithographs).  For those who can't wait for such things, here
is the results of their phylogenetic analysis:

Theropoda
Sauropodomorpha
  Prosauropoda (which they regard as monophyletic)
  Sauropoda
    _Vulcanodon_
    Eusauropoda
      _Shunosaurus_
      unnamed
        _Barapasaurus_
        unnamed
          _Omeisaurus_
          Neosauropoda
            Diplodocoidea
            Macronaria
              _Haplocanthosaurus_
              unnamed (actually, Camarasauromorpha of Salgado et al. (1997)
                _Camarasaurus_
                Titanosauriformes
                  Brachiosauridae
                  Somphosondyli
                    _Euhelopus_
                    Titanosauria

Interesting results, with Upchurch's version of "Euhelopodidae" splashed to
the four winds (_Shunosaurus_ a basal eusauropod, _Omeisaurus_ the sister
taxon to Neosauropoda, and _Euhelopus_ a derived titanosauriform
macronarian) and _Shunosaurus_ with a more basal position than
_Barapasaurus_.  Otherwise, though, pretty standard results that most people
are getting: Neosauropoda is a fairly strong clade, as is
Macronaria/Camarasauromorpha (and Diplodocoidea, but the support for the
last was not tested directly in this analysis).  As reported on the
listserve, Upchurch is also finding a version of Titanosauriformes (?and
Macronaria/Camarasauromorpha?) in his most recent analyses.

Conspicuous by their absence are: _Mamenchisaurus_, _Rebbachisaurus_,
_Rayososaurus_, the In Abaka sauropod (okay, it still has to be described,
but I was hoping it was going to come out in this paper...), _Cetiosaurus_,
_Phuwiangosaurus_, _Astrodon_/_Pleurocoelus_, and ingroup relationships of
Diplodocoidea and Titanosauria.  Granted, this would make things even longer
and more complicated, but I'd still like to see where these fit in this tree.

Some of these taxa not used in the analysis, and their probably phylogenetic
positions are discussed in the text (_Rayososaurus tessonei_ (new
combination) and _Amphicoelias altus_ as basal diplodocoids outside the
Diplodocidae-Dicraeosauridae clade; the French "_Bothriospondylus"
madagascarensis_ material, _Eucamerotus_, and _Pleurocoelus_ as
brachiosaurids; _Nemegtosaurus_ and _Quaesitosaurus_ as titanosaurs; etc.).


Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661