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Re: Opisthocoelocaudia



In a message dated 95-09-21 00:04:54 EDT, zooamy@zoo.latrobe.edu.au (Adam
Yates) writes:

>In Sereno's Science paper dealing with the Saharan dinosaurs, he 
>mentioned a reference that included Opisthocoelocaudia (hate that name) 
>within the Titanosauridae, which Sereno concured with. I have been unable 
>to get hold of this paper, has anyone seen it and can they tell me what 
>evidence there is for this move? At first glance they seem to be rather 
>dissimilar sauropods.

Right. _Opisthocoelicaudia_ had, as its name implies, opisthocoelous caudal
vertebrae, which are exactly reversed from the procoelous configuration that
diagnoses Titanosauridae. It also had bifurcated presacral neural spines,
which titanosaurids lacked (at last look). Nor is the pelvis of
_Opisthocoelicaudia_ similar to that known in titanosaurids (e.g.,
_Saltasaurus_). All in all, it is impossible for _Opisthocoelicaudia_ to be
classified as a titanosaurid based on current knowledge. Interestingly,
however, the forelimb of the South American sauropod _Argyrosaurus_ is very
similar to that of _Opisthocoelicaudia_, and _Argyrosaurus_ is presently
classified in Titanosauridae (although not if I have anything to say about
it). If this is the way that _Science_ paper does indeed have it (I can't run
off and confirm it at the moment), it wouldn't be the only shortcoming of the
paper, by the way. (Bah! Five co-authors!)

I think the name _Opisthocoelicaudia_ might have been coined in frustration
over all those dinosaurs named after features of their vertebrae, such as
_Pleurocoelus_, _Streptospondylus_, _Sphenospondylus_, _Caudocoelus_,
_Bothriospondylus_, etc. Maybe.