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Re: Spinosaur crests & sails



Overall a very interesting theory. I dont think that dinosaurs like _S.
tenrensis_ would spend a lot of time in the water. I think they would
spend time around the shallow rivers that ran in the Cretaceous in Niger.

The crocodile that you might mean is _Sarcosuchus imperator_. A crocodile
which can grow to HUGE sizes, an estimated 50 ft. or so. (Check out Sereno's
last expedition to Niger). 
I would imagine some kind of interaction between _S. tenerensis_ and
_S. imperator_. 

About the crest, the crest is not so big on all spinosaurs, a long, low
crest (or part of it) can be seen in Taquet et Russell (1998) in their
description of _Cristatusaurus lapparenti_, I know this might be a syno0nym
to _S. tenerensis_, but that is another argument. Anyway, an articulated
premaxilla and maxilla are referred to _S. maroccanus_,  a possible junior
synonym to _Spinosaurus aegyptacus_, but indeed a spinosaurine. Now the
crest on _S. tenerensis_, that one can be seen. If the crest would be
in the water, wouldn't that make the nostrils be under water? If not,
then the whole animal has to be inside the water. 
I dont imagine that a Suchomimus would be able to stand or float underwater,
the body is built like any other theropod and it is built to be in land.

Another thing to consider is that Spinosaurs do not only eat fish, they
also eat other dinosaurs (_Baryonyx walkeri_, Charig and Milner 1997).

 
Overall, a good theory. It needs to be put to the test. 
Ah, I just remembered, I believe MIke Keesey has an animation on his
website that shows Baryonyx eating. It looks carefully then strikes.
An interesting theory though. 
Just some thoughts.
-Marco  
 
-- 
Marco A. Mendez
Atomic DinoLab
spinosauroidea@onebox.com - email
(773) 377-5006 x2159 - voicemail/fax
IM: Spinosauroidea


---- Waylon Rowley <whte_rbt_obj@yahoo.com> wrote:
> To James:
> 
> Check out the skulls of Suchomimus, Baryonyx, and
> Irritator to see some of these crests I mention. The
> fact that there are plate-like crests on these guys
> makes me think spinosaurs used a quick forward snatch,
> instead of slowly moving their heads back and forth
> until they sense their prey (like some wading birds),
> but spinosaurs seem to lack the traditional sigmoidal
> shape to the neck which would be needed when preparing
> for the strike...However, one synapomorphy of
> Baryonychinae is; "blade-shaped depth of ventral keel
> on anterior dorsals", which would occupy the same
> position as hypapophyses and may have had a similar
> function? It's curious that they don't migrate up to
> the cervicals, though. So, if it can't strike very
> well, and doesn't employ a sweeping mode of hunting,
> then it probably just swam (or waded) right up and
> nailed the critter it was after. Personally, I don't
> think many theropods had trouble swimming. If I
> remember correctly, Spinosaur tails have transition
> points further back in the caudal series than most
> tetanurans...this might be a secondary loss of
> intervertebral articulation in response to the need
> for more efficient swimming. Perhaps the reason these
> particular species grew so large was due to their
> semiaquatic lifestyle. It makes me wonder if the
> massive arms and claws could have been used to help
> lift their huge bodies when getting out of the water
> or steadying themselves on boulders or logs in a fast
> current. You're probably right about the age
> difference between Deinosuchus and Suchomimus, but I'm
> sure other similarly-sized crocs were present in its
> habitat. Must go TTYL
> 
> -Waylon    
>    
> --- JAMES ARONIS <Apollo@MLink.net> wrote:
> > Very interesting theory, although I wasn't aware of
> > any cranial crests
> > among the Spinosaurs. In addition, I believe that
> > Spinosaurus predated
> > Deinosuchus by several million years, IIRC.
> > Moreover, it is not known if
> > Spinosaurus or its relatives were as aquatic as the
> > crocodilians.
> 
> 
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