Re: Triassic Sauropods

[Dinogeorge@aol.com]

In a message dated 4/6/01 11:19:29 PM EST, qilongia@yahoo.com writes:

<< Possibly. Premise #1: *Nemegtosaurus* and *Opisthocoelicaudia*
 are synonymous. Refutation: Preservation does not find this
 synonymy; we must conclude the premise plausible, not a basis
 for diagnosis or analysis. >>

Translation: We'll keep Nemegtosaurus and Opisthocoelicaudia separate for the 
time being, until we find a skeleton of one or the other with both skull and 
postcrania. I have no problem with this, of course; but I would refer 
Opisthocoelicaudia to family Nemegtosauridae based on my own interpretation 
of the phyletic positions of Nemegtosaurus and Opisthocoelicaudia. Once this 
is done, it becomes most peculiar to have two different sauropod genera in 
the same family from the same formation, one known only from cranial 
material, the other known only from postcranial material. Of course, 
sympatric sauropod genera in the same family are known from the Morrison 
(e.g.), so it's of course not impossible for there to be two distinct 
nemegtosaurids in the Nemegt Formation. We need some more material before the 
situation can be resolved.