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RE: stegosaur

>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 (home)
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