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Re: Spinosaurus teeth

On Fri, 11 Aug 1995, th81 (aka Tom "The Dino Man" Holtz) wrote:

> Temperature radiators might be useful for either warm or cold blooded
> animals, so it's hard to say.  What is more interesting (to me, anyway) is
> the fact that sails appear in bursts in geologic time, but across many
> different evolutionary lines (as Greg Paul has pointed out).  The first of
> these was the Late Pennsylvanian-Early Permian, when the sphenancodontid
> Dimetrodon, the edaphosaurids Ianthasaurus and Edaphosaurus, and the
> amphibian Platyhystrix all developed sails.  The second was in the late
> Early Cretaceous, when the dicraeosaurid Amaragasaurus, the sauropod
> incertae sedis Rebbachisaurus, the spinosaurid Spinosaurus, and the
> iguanodontid Ouranosaurus all developed sails.  Weird, huh?

Weird!  I think it's fascinating.  The thing that is most interesting to 
me is that it must take many many generations for an adaptation such as a 
sail.  One thing that seems strange to me is that nature would go that 
direction at all.  I have the Dinosaur series that was on PBS and narated 
by Walter Cronchite.  In it is an interview with my favorite story teller 
Robert Bakker.  Bakker makes a the point that nature is a conservative  
(my words) in adaptation and that nothing developed is for nothing.  He 
claims that nature is efficient and things don't get developed unless 
there is a compelling reason to do so.  He sez this while under a 
reconstruction of Brachiasaurus.  

I guess the my puzzlement lies in the fact that T-rex didn't need a sail 
so be succesful, but Spinosaurus did.  Why?  Was the climate.  Was it 
that  Spinosaurus had an easier life than T-rex which allowed for energy 
to be put into vanity ie. display?  

It seems to me that a sail would make a great thing to grab onto while 
"attempting" to bring one of these bad boys to the dinner plate. 

Don't get me wrong I like the sail idea, it just boggles my mind at the 
amount of energy this species must have spent over generations in order 
to develop a sail of that size.

        Greg Claytor
        Dino Nut