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RE: Spinosaurs as what?



On Fri, 25 Feb 2005, Tim Williams wrote:
> Renato Santos wrote:
> 
> >the animal could use its shade as a way to diminish the glare the water's 
> >surface produces thus being able to see the fish more clearly.
> 
> Dorsal sails are also seen in _Ouranosaurus_ and some "pelycosaurs".  
> _Altispinax_ may have had a sail too; although it's also been suggested that 
> its elongated spines supported a hump rather than a sail.
> 
> The idea that _Spinosaurus_ used its sail as a shade-giver is interesting, 
> but highly speculative.  It's also undermined by the fact that evidence for 
> dedicated piscivory in spinosaurs is ambivalent.  Interestingly, there is an 

Since the sail runs down the back, it would have to stand sideways for
this to provide shade. If this then was supposed to attract fish, then the
critter would have to be looking over its shoulder to see if any fish
showed up (not to mention the difficulty in striking at a fish from this
position).

> old idea that the ancestors of birds originally evolved wings for this 
> purpose (as shade-givers to lull fish into coming close, as in modern 
> herons): the larger the wing, the more shade it could generate.  This idea, 
> like so many others that attempted to explain the origin of incipient 
> feathered wings, has been largely discredited.