RE: stegosaur

[Crpntr@ix.netcom.com (Kenneth Carpenter)]

You wrote: 

>
>>Yes, because both Stegosaurus stenops and the smaller plated 
Stegosaurus 
>>armatus occur in the same fossil deposits (e.g. Marsh-Felch Qaurry).  
>>Also, the paleoenvironment of the Chinese sites are similar to that of 
>>the Morrison Formation - i.e. semi-arid, seasonal rain fall. Therefore 
>>the thermo regime was similar for the various stegosaurs.
>>
>>The vascularized plates simply mean that abundant blood was available 
to 
>>the plates and would allow them to "blush" in display.
>>
>Thank you for the clarification.
>
>"Blushing" in display is of course well known for some birds with areas 
of
>vascularized bare skin (honeyeaters of the genus Melipotes come to 
mind).
>However, I am still not entirely convinced.  Even if the primary 
function of
>the plates was display, their vascularization would surely have caused 
them
>to have, at least passively, some thermoregulatory effect (indeed I am 
not
>sure how S. stenops could have avoided this unless there was some
>complicated shunting mechanism involved). Further, African elephants 
(which
>occupy an extremely wide range of thermal regimes) use their ears both 
for
>display and thermoregulation, despite the fact that Asian elephants 
have
>much smaller ears (in fact a palaeospecies of Elephas coexisted with
>Loxodonta africana at Olduvai, though of course we don't know how big 
its
>ears were).  Is it at least possible that there were behavioural 
differences
>among sympatric stegosaurids that may have had thermoregulatory 
consequences?
>--
>Ronald I. Orenstein                           Phone: (905) 820-7886 
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>International Wildlife Coalition              Fax/Modem: (905) 569-0116 
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>Toronto, Ontario Canada M5H 3P5             
>
>
>

I am not against the plates having a secondary role for 
thermoregulation.  Having that large of a surface area makes it 
inevitable. However, considering the diversity of plate size and shapes 
among stegosaurs, I argue that the major role was species recognition or 
display (threat or sexual).  Considering that the two species of North 
American Stegosaurus' co-occur in Colorado (e.g. Marsh-Felch) and 
Wyoming (e.g. Quarry 13, Como Bluffs) they were both subjected to the 
same climatic conditions.  Yes, I do think that there was behavioral 
separation of the two species, but this does not necessarily imply 
living in different habitats.

You seem to disagree with my hypothesis.  What is your's?  You hint at 
something in your last sentence but do not elaborate.