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Upchurch's new phylogeny



Finally have a copy of Upchurch's new sauropod phylogeny paper (1998.  Zool.
J. Linnean Soc. 124: 43-103).

Good stuff.  Unfortunately, it came out too late to address Wilson &
Sereno's big new analysis (some mention is made of the poster by Jeff & Paul
back at the 1994 SVP meeting, but unfortunately Upchurch was unable to
compare his data matrix with the monograph).  It will be interesting to see
how these data matricies mesh together, as some basic elements (basal guys +
(Diplodocoids + (_Camarasaurus_ + (Brachiosauridae + titanosaurs)))) are
found in both analyses.

Some details:

26 taxa, 205 characters, 2 most parsimonious trees in the primary analysis
(difference is an unresolved relationship between the long-necked euhelopodids).

Euhelopodidae is retained, with the structure _Shunosaurus_ + (_Euhelopus_ +
_Mamenchisaurus_ + _Omeisaurus_), as the sister group to the "cetiosaurs" (a
paraphyletic smear of _Patago-, _Cetio-, and _Haplocanthosaurus_) and
Neosauropoda.  Monophyly of the euhelopodids does not hang on tail clubs,
which Upchurch now recognizes as an autapomorphy of _Shunosaurus_.

Nemegtosauridae is retained as the sister group to _Rebbachisaurus_ +
(Dicraeosauridae + Diplodocidae) within Diplodocoidea.

_Lapparentosaurus_ is (provisionally) considered a brachiosaurid;
_Phuwiangosaurus_ is provisionally a basal titanosaur.  _Opisthocoelicaudia_
remains DEEPLY nested among the titanosaurs (sister taxon to _Saltasaurus_,
with _Alamosaurus_ as an outgroup).

Some discussion of bootstrap analysis, decay analysis, and randomisation
analysis, to discover (to nobody's surprise) that some taxa
(_Haplocanthosaurus_ and _Lapparentosaurus_, for example) are not securely
placed anywhere.

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