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Tangvayosaurus hoffeti (Sauropoda: Titanosauria), n. gen. et n. sp.



Hi, all!

The latest block of issues of Comptes Rendus de l'Academie des Sciences.
Science
de la terre and des planetes is in.  Among them is ANOTHER new sauropod,
this time a titanosaur from Thailand:

Allain, R., P. Taquet, B. Battail, J. Dejax, P. Richir, M. Veran, F.
Limon-Duparcmeur, R. Vacant, O. Mateus, P. Sayarath, B. Khenthavong & S.
Phouyavong.  1999.  Un nouveau genre de dinosaure sauropode de la formation
des Gres superieurs (Aptien-Albien) du Laos.  C.R. Acad. Sci. Paris,
Sciences de la terre et des planetes 329:609-616.

The dinosaur in question is _Tangvayosaurus hoffeti_, named after the type
locality (Tang Vay, Savannakhet Province, Laos) and Josue'-Heilmann Hoffet,
discoverer of previous Laotian dinos.

Two partial skeletons are found, indicating it was a 15 m long primitive
titanosaur, similar to the Late J/Early K _Phuwiangosaurus_ of Thailand.
Although they don't run a phylogenetic analysis on this puppy, they have
observed macronarian, _Camarasaurus_ + titanosauriformes, titanosauriform,
and titanosaur features in the skeleton.

Femoral remains are similar those found by Hoffet and referred by him to
"_Titanosaurus" falloti_; however, the type material of the latter does not
possess autapomorphies and neither it nor _Tangvayosaurus_ show diagnostic
characters of _Titanosaurus_.  The authors consider Hoffet's taxon a nomen
dubium.

A note on _Saturnalia_: the authors assert it is the basalmost
sauropodomorph, but that hypothesis is untested.  In their phylogenetic
analysis the only two sauropodomorph operational taxonomic units are
"_Saturnalia_" and "other sauropodomorphs": thus, a position of _Saturnalia_
nested within previously known sauropodomorphs is impossible given the set
up of the study. On the other hand, their study included _Staurikosaurus_
and _Herrerasaurus_ as OTUs (the remaining two are Ornithischia and
Theropoda (really Neotheropoda).  Their analysis found two equally
parsimonious trees: one where _Staurikosaurus_ and _Herrerasaurus_ form a
paraphyletic grade outside the sauropodomorph + theropod clade, and another
with a monophyletic _Staurikosaurus_ + _Herrerasaurus_ outside of
Dinosauria.  Unfortunately, neither the matrix nor the tree metrics are
provided, nor is the outgroup(s) used indicated.

Interesting stuff.  Sauropodomorphs seem to be coming out of the woodwork
now...

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-314-7843