Re: Spinosaurus Question

[Tim Williams <twilliams_alpha@hotmail.com>]

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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