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In a message dated 96-10-04 19:10:45 EDT, longrich@phoenix.Princeton.EDU
(Nick Longrich) writes:
> Which is simply ridiculous. Not the proposal, but that it is the
> "only way". Everybody here should know that feathers are unsurpassed as
> insulatory structures. To use George's argument, if they're so wonderfully
> adapted for insulation, why argue they evolved for something else?
Of course, the answer to this is that ANY kind of hairlike or featherlike
dermal structure would almost automatically be "wonderfully adapted for
insulation" if it simply covers the skin densely enough. The problem is not
understanding the evolution of insulation; the problem is understanding
specifically the evolution of structured feathers. This is where the BADD
theory goes _ad hoc_ on us.
But the main question is, Did avian ancestors REQUIRE insulation? That is,
were they endothermic? It has begun to look as if avian ancestors (and other
dinosaurs) were active >ectotherms<, not endotherms after all. If this turns
out to be the case, then the insulation argument cannot hold, and we must
look elsewhere for the proximate cause of feather evolution.