RE: NON-CLUBBED SAUROPODS

[Adam Yates <A.Yates@zoo.latrobe.edu.au>]

>Most everyone else has published cladograms that show Shunosaurus as
being a
much more basal sauropod and Omeisaurus as the outgroup to Neosauropods.
Wilson and Sereno even make a good case (in my mind) that Euhelopus is
actually a basal titianosaur [with this I am assuming that had they ran
Mammenchisaurus, it would have claded with Omeisaurus].<

Yes Mamenchisaurus probably would form a clade with Omeisaurus based on the
two sharing very elongate neck vertebrae, very low neural spines on the
cervicals and an increased number of cervicals. Mamenchisaurus also lacks
such Neosauropod apomorphies as a fully closed external mandibular fenestra
and a non-denticulated teeth. However Mamenchisaurus also seems to have
developed some Camarasauromorph characters independantly (opisthocoelous
posterior dorsals being the most significant). It also shares a number of
features with Euhelopus (reduced cervical pleurocoels for one) so I think if
Mamenchi were included in Wilson and Sereno's matrix it would have a
destabilising affect and the inclusion of Euhelopus in the Titanosauriformes
wouldn't look so rosy.

cheers

Adam Yates