Re: Astrodon vs Pleurocoelous

[Tompaleo@aol.com]

Hi Tim,

Thanks for the ref cite! I was not aware of it until now. Thus I am at 
somewhat of a disadvantage.
I will have to pull this down and digest it for a while.


>  If all the Arundel sauropod skeletal material (_P. nanus_ & _P. altus_) 
does 
> 
>  indeed belong to a single species, then it makes sense to assume that the 
>  sauropod teeth (_Astrodon johnstoni_) also belong to this species, and to 
>  call that species _Astrodon johnstoni_.  But if there is some doubt on 
this 
>  issue (as raised by Salgado et al.: "P. altus does not appear to 
correspond 
>  to an adult of P. nanus, as was proposed be various authors"), then the 
>  tooth taxon _A. johnstoni_ cannot be combined with either skeletal-based 
>  taxon from Arundel.
  
I have no argument with that in that if the material (P. _altus_ and 
P._nanus) are truly different at a generic and/or specific level. 

>  
>  I think on this point we are in complete agreement.  The referral of any 
>  non-Arundel material to _Pleurocoelus_ should be reconsidered.  The 
>  "Pleurocoelus" material from Oklahoma is now _Sauroposeidon_, and the 
>  Comanche "Pleurocoelus" material (AFAIK) certainly belongs elsewhere 
>  (related to _Cedarosaurus_?).  The implication of Salgado et al's work is 
>  that _Pleurocoelus_ should be limited to the type species (_P. nanus_).


 
>  
>  >The point(s) I want to emphasize regarding the Arundel sauropods that at
>  >present, "Pleurocoelus sp." of any kind are not generally regarded to 
occur
>  >in the Arundel.
>  
>  I'm a little confused here.  The type material for _Pleurocoelus_ is from 
>  Arundel.  True, certain Early Cretaceous sauropod material from North 
>  America has been referred to this genus (as "Pleurocoelus" sp.). 

That is my fault. What I should have said was; while it is true that the 
material currently in the collection (except for teeth) are all catalogued 
under either species of _Pleurocoelus_  (Marsh),  the body of opinion 
regarding it however favors the notion that based on the material at hand, it 
more likely represents ontogenetic variants of the same gen. et. sp. of  
_some _ sauropod and none of the referred specimens have very diagnostic 
characters (at least prior to now). Due to the disarticulated and fragmentary 
 nature of the remains and limited areal extent of productive outcrops  (ca. 
1880s all  of which are now gone save but for my site) then the isolated, 
shed sauropod teeth found from the same area as both the teeth as originally 
described by Leidy (1865) and the remains described by Marsh seem to be 
related. If this is so, then priority rests with _Astrodon_ . 
However,  as I understand it according to the ICZN, should an actual skull 
with in situ _Astrodon_ teeth ever be discovered,  it would have to be 
described and given another name thus sinking _Astrodon_ and _Pleurocoelus_ 
since it is believed that none of the referred remains possesses any truly 
genreric/specific diagnostic characters. 


>But I think 
> 
>  we can be reasonably certain that this material does not belong in the 
same 
>  genus as the type _Pleurocoelus_ species (which, if there is indeed one 
>  sauropod species from Arundel, can be referred to _Astrodon_.  If not...).
>  

I still need to see the paper and to review the literature and material. In 
fact, the latter already been discussed between myself and another 
individual. Regardless of outcome, this is an interesting proposition and 
Salgado et al. might help to force us to get started on reevaluating 
Astrodon/Pleurocoelus ASAP!


>  Thanks for the info!

And thanks to you as well!

Cheerers,

Tom

Thomas R. Lipka
Paleontological/Geological Studies
Tompaleo@aol.com