RE: synonymous sauropods?

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Tim Donovan wrote:

> The recent discovery of tracks which match the pes of O. skarzynskii in
> the Central Sayr, close to the site that yielded the type skull of N. 
> mongoliensis, suggests the two are the same. So does the discovery of 
> opisthocoelous caudals in the nearby Western Sayr.

                             
The mooted synonymy of _Nemegtosaurus_ and _Opisthocoelicaudia_ is looking
increasingly promising.  After all, the two genera do pop up in the same
part of the titanosaur tree.  

However... until overlapping material comes to light that *proves* the two
genera are one and the same, I believe it's premature to synonymize
_Opisthocoelicaudia_ with _Nemegtosaurus_.  It is possible that two
titanosaur genera existed in the same place at the same time - as happened
in Madagascar, India and South America during the Late Cretaceous.  (Maybe
North America too - depending on the provenance of the sauropod material
referred to _Alamosaurus_.)  After all, by the end of the Cretaceous
(Campanian/Maastrichtian), genera belonging to the Titanosauria appear to be
the only sauropods left.



Tim