Questions on Opisthocoelicaudia

[DRosent288@aol.com]

I have some questions on the continuing debate on the classification of 
Opisthocoelicaudia:

1.  What are the particular features of O. that led to its being reclassified 
as a
titanosaurid--or at least a titanosauroid?  Is there an article on this, 
besides
Upchurch's?

2.  I think it has been suggested that O. may be a derived Euhelopodid.  Don't
euhelopodids have forked chevron bones (like diplodocids and dicraeosaurids)?

3.  A new family, Nemegtosauridae, has been been erected for Nemegtosaurus
and Quaesitosaurus.  I have asked previously if one of those might be the head
of Opisthocoelicaudia.  (In fact, I have heard a suggestion that N. and O. 
are not
only the same species--they may be the same *invidual*--the head may have 
washed downstream.)  If O. is in fact a titanosaurid or titanosauroid, what 
effect
does this have on the validity of Nemegtosauridae?

4.  Assuming that O., N. and Q. are titanosaurids or titanosauroids, have any 
non-
titanosaur sauropods been found in the Upper Cretaceous?  If not, why did only
the titanosaurids survive--what survival advantage did they have over other 
sauropods?  (I used to think it might be dermal armor, but apparently not all
titanosaurids were armored.)

5.  Has an endocranial cast of the brain of Nemegtosaurus or Quasitosaurus 
been
made?  If so, how does the brain or brains differ from those of other 
sauropods, if
at all?  My understanding of sauropod brains is that they were very tiny 
given the
overall size of these animals.