RE: Pleurocoelus vs. Astrodon

["Tim Williams" <twilliams_alpha@hotmail.com>]

Rob Gay wrote:

> I don't
> remember if it talks about _Astrodon_, but in the lit. cited section, there
> are somethings about the Comanche fauna; specifically:
> Lagston, W. Jr. 1974. Nonmammalian Comanchean tetrapods. Geoscience and Man
> 8:77-102


I've read this paper, and the sauropod described is provisionally referred 
to _Pleurocoelus_ by Langston.  However, in the light of further Cretaceous 
North American sauropod material gathered (or described) more recently, it 
appears that the Comanche sauropod is NOT in fact _Pleurocoelus_.  Among the 
differences, the tail vertebrae of the Arundel _Pleurocoelus_ and the 
Comanche "Pleurocoelus" are quite different.  The latter might be 
_Cedarosaurus_ or a new titanosauriform genus.

The question of just what IS _Pleurocoelus_ is a curly one.  The 
proportionately large pleurocoels of the Arundel type material is likely to 
be a juvenile trait (as Ken Carpenter believes); juvenile _Camarasaurus_ 
material was once assigned to the genus _Pleurocoelus_ because of the very 
large pleurocoels.  Also, the juvenile material on which the genus 
_Bellusaurus_ was founded also shows very large pleurocoels.  For this 
reason, Dong thought _Pleurocoelus_ and _Bellusaurus_ might be close 
relatives and he put them in the same subfamily, but it's probably just a 
juvenile trait seen in all young sauropods.


Tim



------------------------------------------------------------


Dr Timothy J. Williams
USDA/ARS, Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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