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RE: _Suchomimus/Cristatusaurs_ (was: _Spinosaurus_)



---- Jaime A. Headden <qilongia@yahoo.com> wrote:
>   *Suchomimus tenerensis* [Sereno, Beck, Dutheil, Gado, Larsson, Lyon,
> Marcot, Rauhut, Sadlier, Sidor, Varricchio, Wilson, Wilson, 1998] from
> the Gadoufaoua of Niger has few differences from *Baryonyx* aside from
> size, shape of the sail, shape of the snout and dorsal crest with
> proportion of teeth (more), more robust forelimbs and epiphyses
> especially, and big olecranon. There may be a few more. I am cautious
> thinking of this as a new genus, and it could serve equally well as
> a
> species of *Baryonyx*. The skull can come out to ~4ft, and the body
> about 36ft or so. Interestingly, the deep opisthocoely seen in
> *Spinosaurus* and *Baryonyx* in the cervicals and anterior dorsals
> is
> not as pronounced, and the epiphyses of the centra in these elements
> are not as large, so this taxon may be closer to the primitive state
> than other spinosaurids. The premaxillae of *Cristatusaurus* differ
> very little from *Suchomimus*, and this is curious, because the
> suchomime snouts fall between the two cristatusaur snouts in
> proportion:
> 
>   *Cristatusaurus lapparenti*, holotype:  185mm/95mm     (fused)
>   *Suchomimus tenerensis*, holotype:      154mm/107.7mm  (part fused)
>   *Cristatusaurus lapparenti*, referred:  115mm/55mm     (unfused)
> 
>   despite being a little taller; this can be considered both
> ontogenetic and variable within the form. The dorsal margin of
> *Suchomimus'* snout is a narrow ridge, but not a midline crest, as
> in
> *Irritator*. The variation of the alveoli is similar, as is the
> arrangement, and both bear finely serrated crowns with similar
> compression (weak and sub-conical). My recommendation? They're the
> same
> taxon.<
   

Sereno does write this in the description of _S. tenerensis_ : 
"However, no distinguishing features or proportions are apprent to us
or to prevous authors, who attributed the premaxillae to an undeterminate
species of Baryonyx. Therefore we regard C. lapparenti as a nomen dubium"

The authors that describe _C. lapparenti_ do claim the material is not
the same as _Baryonyx walkeri_  or _Irritator challengeri_. It has been
claimed that some _B. walkeri_ material has been found in Niger, especially
teeth (A.J. Charig and A.C. Milner, Bull. Nat. Hist. Mus. 1997). 
Over reading this paper this moment, it is written under Oher Material
Reffered, that Taquet (1984) described two fragements from the Gadoufaoua
formation of Niger ( MNHN GDF 365 and 366).  It also states that each
of these fragments are identical to the premaxillae of _Baryonyx walkeri_,
the only difference is the premax teeth ratio 6/7 (_B. walkeri_) to 7/7(in
 MNHN GDF 365 and 366). Although younger in age, both these fragments
(premaxillae) are reffered to Baryonyx sp. indet. 

It may be that MNHN GDF 365 and 366 are comparable to _S. tenerensis_
because of it's similarities with Baryonychids. 
Although MHNH GDF 365 and 366 are not complete enough to compare. I do
think that the holotype for _S. tenerensis_ is a subadult, so i  think
it gets bigger. the body lenght is about 36-feet. 
That's what i think, but we need more Spinos and material!!! :) 

happy holidays to everyone, 

-marco mendez



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