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Help-info on stegosaur plates #2 (LONG)



Just sending a copy of the letter I posted last week, haven't had any
replies yet, which I guess indicates either no one has any further
information, or I have not sent the message in correctly (being first time
sender to a list like this). So here it is again (let me know if this is a
second posting):    
  

-------------------------------------------------------------
Hi,
This is my first letter to this mailing list, so bear with me...

I'm currently doing a uni assignment on the "growth and function" of the
plates of Stegosaurus, and urgently need more references and information.

A fairly good paper is supplied by de Buffrenil, Farlow, and de Ricqles
(1986) entitled "Growth and function of Stegosaurus plates: evidence from
bone histology", which seems sufficient, but I would prefer to have more
than just one view point on the subject. 

Any one know of other work on this topic? Any more recent work?  

I've exhausted all avenues available to me at this end (I do have some of
the  popular books as back up Bakker's "The Dinosaur Heresies", Czerkas'
"Dinosaurs: a Global View", and David Norman's "Dinosaur!" and "The
Illustrated Encyclopedia of Dinosaurs").

Anyway, if any one knows of anything please let me know 

Thanks 
Chris 

PS Please ignore silly signiture.

--------------------------------------------------------------------


So, does anyone know of anything that discusses these points, and that might
offer alternative views to the literature I have? (I live in a small town
with limitted library resources, hence this message)

de Buffrenil et al indicate that the bone structure of the plates of
_Stegosaurus_ was too light and weak to allow them to be used as armour, and
study of the surface of the plates' surfaces indicate that no horny sheath
was present,leaving the thermoregulatory role as the best reason for their
existance (and display as a secondary use of these structures). de Buffrenil
et al also mention that it appears the tail spikes' were also weak and
sheathless, and also doubt their role as armour. 

If this is so, how did these plate and spine structures develop in an
evolutionary sense? Other stegosaurs have smaller plates or just spines that
I would have thought wouldn't be the most optimal shape for a
thermoregulatory device. These structures on the other stegosaurs appear
more armour-like in general shape to me, (as do the tail spines of
_Stegosaurus_). Wouldn't a horny sheath hinder any thermoregulatory function
of these structures, or would it conduct heat to and from the blood vessels
below? 

I would guess that the horny sheath would be insulatory and the armour and
thermoregulatory functions would be mutually exclusive.

If other stegosaurs (and the ancestor of _Stegosaurus_) had horny sheaths
and denser bone on their smaller plates and spines then the evolution of
these into thermoregulators is appear to be unlikely due to the need of a
non-functional (or at least "less-functional") intermediate stage of weaker
bone and horny sheath, and poor heat exchange properties due to the sheath
and small surface area. Perhaps the intermediate animal was compensated by
increased "signage area" for sexual and/or defensive display as the spines
broadened into plates. 

I guess a similar situation has occured in the development of the antlers of
the moose, where sexual display compensates for their combersome size and
shape. (NB. I am not a moose expert). By the way, anyone know if moose
antlers over heat or cool off too much?

Another point I've been looking at is the orientation of the plates. There
seems to be a gerneral acceptance of the recent model of one row of plates,
with some alternation as proposed by Czerkas.  

If anyone has some "citable" information that supports refutes these points
please send it to my email address. 

Anyway, this message is probably lengthy enough,



 <'\                                Christopher Glen            
   \\   ______                      PO Box 399     
    \\_/ ```` \                     Noosa, Queensland 4567         
     \__ \__/ /\                    Australia           
       ||| |||\_======-----                                  
       ""  ""    
"Life's a bitch, and then you die" - pessimist
"Life's a bitch, and then you get reincarnated" - pessimistic buddhist