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Re: Spinosaurus Question



Has anyone ever designated a lectotype from among the _Spinosaurus_
material (assuming that all the original material had equal type
status)? In the event of the _Spinosaurus_ hypodigm containing
material from multiple species, does the name stay with the dorsal
spines, or is this potentially an _Altispinax_/_Vulcanodon_-type
situation where the name is based on a feature not demonstrable in
the actual type material?

    Cheers,

        Christopher Taylor

---- Original Message ----
From: twilliams_alpha@hotmail.com
To: dinosaur@usc.edu
Subject: Re: Spinosaurus Question
Date: Mon, 02 Apr 2007 18:42:16 -0500

>Jamie Stearns wrote:
>
>>Aside from size, is there any other correlation between the dorsals
>and the 
>>cranial material? As in, are the proportions of the dorsals (besides
>neural 
>>spine length) consistent with what we know from Baryonyx and
>Suchomimus?
>>
>>I've also heard that Rauhut mentioned the dorsals might be from a 
>>carnosaur. Could they possibly be from Carcharodontosaurus if
>they're not 
>>from Spinosaurus? I'm not really sure how many Carcharodontosaurus
>dorsals 
>>are known.
>
>You're right.  Rauhut suggested that the _Spinosaurus_ dorsals may
>come from 
>an _Acrocanthosaurus_-like carcharodontosaurid.  Rauhut notes that
>the 
>dorsals of _Spinosaurus_ are quite different from those of _Baryonyx_
>and 
>_Suchomimus_ in the absence of strong pneumatization and laminae, as
>well as 
>in the presence of exceptionally tall spines.  _Suchomimus_ has
>rather tall 
>spines that increase in height from the mid-dorsals onwards, but they
>don't 
>hold a candle to those of _Spinosaurus_.  Also, the "sail" of
>_Spinosaurus_ 
>reaches its peak over the mid-dorsals, whereas the lower sail of 
>_Suchomimus_ reaches its greatest height over the sacrum.  _Baryonyx_
>shows 
>some "incipient" development of a sail, according to Sereno et al.
>(1998).
>
>Aside from the cranial elements, Rauhut suggests that the cervical,
>dorsals 
>and caudal (proximal) assigned to _Spinosaurus aegyptiacus_ may each
>come 
>from a different animal.
>
>No incontrovertible dorsals are known for _Carcharodontosaurus_. 
>Several 
>dorsals have been referred to _Carcharodontosaurus_, but it is not
>clear 
>that they belong to this taxon as opposed to some other large Saharan
>
>theropod.
>
>Cheers
>
>Tim
>
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