On Thu, 5 Jun 2003 13:48:14 +0000 (UTC), Fidcal
 wrote:

>On Wed, 4 Jun 2003 04:09:40 +0000 (UTC), r norman
> wrote:
>
>>In other words, the generally accepted sequence is, first, some
>>partial degree of keeping your core body temperature warm. Second,
>>better ways of insulating the body to improve your temperature
>>regulation. 
>
>Thanks for response. Is there a possibility the insulation came
>first? ie, spiky scales might evolve for some other protection,
>eg, hedgehog-like reptilians, which would also give some
>insulation to a cold-blooded creature; 'endothermic homeotherms'
>being a later adaptation to take advantage of this insulation?

The scales derive from horny keratinized epidermal plates almost
certainly as a way to protect against dessication -- water
evaporation.  The skin of amphibians tends to be quite permeable and
they lose substantial amounts of water through their skin.  Having a
good waterproof skin was one of the two major innovations of reptiles
to a true and complete terrestrial existence.  The second was the
development of the waterproof amniotic egg.  

If some (or many) or the larger dinosaurs were "warm-blooded", then
certainly that came about without the advantage of hair or feathers,
but merely as a byproduct of large size (and subcutaneous fat as an
added insulator).  It is argued that bird feathers are primarily for
insulation rather than flight, but the origin of feathers is a very
difficult and argumentative subject.
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