Re: Spinosaur

["Jack Conrad" <conradjack@hotmail.com>]

> From: "ekaterina amalitzkaya" <eamalitz@hotmail.com>

> I recently recall reading on the web that Suchomimus may be a junior 
> synonym
> of Baryonyx. Are there reasons to seriously believe this. While definitely
> very similar are there no autapomorphies that distinguish Suchomimus.

_Suchomimus_ is distinct from, though similar to, _Baryonyx_ in that the 
neural spines on the vertebrae are very elongate, more so as you approach 
the sacrum.  Additionally, the transverse processes on the anterior caudal 
vertebrae are quite elongate.  Although it would be difficult to justify, 
one could attempt to suggest that these are ontogenetic changes, except 
there is a limited growth series known for _Suchomimus_ (multiple 
skeletons).  There is more, I don't have it with me right now.  If you 
request, I shall try to provide.


> Sereno
> et al claim that Cristatusaurus from the vicinity could be a synonym of
> Baryonyx suggesting that Suchomimus and Baryonyx could have co-existed-?? a
> strange case of speciation?

I *believe* that they are trying to get at the fact that the 
_Cristatusaurus_ material is undiagnostic at the species level.  It might 
well belong to a _Suchomimus_ or a _Baryonyx_.  If you can, get the paper, 
it discusses paleogeography and implications for speciation.

Hope this helps.


Jack Conrad
University of Chicago
Graduate Student, OBA
The Vertebrate Phylogeny Pages
http://www.geocities.com/CapeCanaveral/Hall/1636/

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