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Re: leggo my stego - plates



In a message dated 96-07-11 10:13:10 EDT, you write:

> It strikes me that moving the body to catch or not catch the sun's
> rays or to orient relative to air currents is much easier than moving the
> plates by flexing the skin.  i suspect that moving the plates was as
> easy as it is for humans to wiggle their ears (only about 10% can do it).
> b

I tend to  agree with Bonnie  here with the exception that I believe that the
putative radiator effect from so many plates is at best a secondary benefit.
IMO, the plates just like the spikes were primarly defensive  in nature.
Stegosaurs seem to have been obligate quadrupeds and as such needed some sort
of dorsal  and posterior protection. As far as concious movement of the
plates goes, I doubt it. Since there is no evidence for either muscular or
tendonous attachments of theses plates it seems likeley therefore that the
plates were immovable  and probably hung loosely. Possible exceptions are
those plates nearer to the shoulder/hip regions where normal day to day
Stegosaur activity of the limb muscles may have sent the plates flapping
slightly  or as a fear response (like that of a cat's hair standing on end
when panicked)  when threatened. Which brings me to a thought about the
aftermath of an unsuccessful theropod attack. Is/are there any pathological
evidence on the plates that indicate such attacks?  What if the theropod rips
one of these plates off the Stego's back? Is there any evidence for
replacement of the plates? Or was it likely that such an injury resulted in
the animal bleeding to death since the plates were fed by numerous
cappillaries? I doubt the latter but I have to consider it a possiblity.

Regards,
Thomas R. Lipka
Paleontological/Geological Studies