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RE: Abydosaurus mcintoshi, a new sauropod from the Albian of Utah

Greg Paul wrote:
<Nemegtosaurus is known from plenty of postcranial material, its known as 
Opisthocoelocaudia. Funny how they often end up widely separated on cladograms.>
  The reason this argument has not seen much support is that there is no way to 
disprove it (there being NO overlapping material).
  Both have been included in comparative titanosaur matrices. Postcranially, 
however, *Opisthocoelicaudia skarzynskii* clades with the derived saltasaurs, 
for which cranial material is generally unknown. Cranially, *Nemegtosaurus 
mongoliensis* and *Quaesitosaurus orientalis* appear to clade along with 
*Rapetosaurus krausei,* which is far more conservative in the body plan than 
are derived saltasaurs. If one were to infer that the crania of nemegtosaurus 
like *Rapetosaurus* or *Bonatitan* are also conservative relative to their body 
plans, then it is unlikely that *Opisthocoelicaudia* represents the postcrania 
of *Nemegtosaurus*. Way back in the 90s, when *Rapetosaurus* was unknown, this 
was a reasonable claim to make, as there was no other evidence that might allow 
one to disprove it, but know, there is a substantive wealth of data that show 
that there was as much diversity among titanosaurs as among non-titanosaur 
eusauropods (one reasoning for this of course being that the former were 
replaced by the latter, and as such the latter filling the niches of the 
former, but this is an hypothesis).
Jaime A. Headden
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