Re: Origin of feathers

[Dinogeorge <Dinogeorge@aol.com>]

In a message dated 98-04-18 03:02:17 EDT, Patrick.Norton@state.me.us writes:

<< In the absence of any undisputed fossil evidence of protofeathers, I   
 prefer Regal's theory on the evolution of feathers over Heilmann's not   
 only because I think it has more intuitive appeal, but partly because it   
 is independent of the arboreal/cursorial problem concerning the origin of   
 flight. Accepting Regal's theory means you can have homeothermic   
 feathered creatures that, whether on the ground or in the trees, are   
 preadapted to responding to selection for gliding and flight.  >>

I don't think we know enough about homeothermy to say anything coherent about
how it may have developed in birds and archosaurs. But if you state that pre-
feathers appeared >for< insulation, you imply that homeothermy was already
present >before< the pre-feathers appeared. (Otherwise, what would they be
insulating?) That is, that homeothermy >without< pre-feathers (or other
insulation) is possible. That is, that pre-feathers are not >necessary< for
homeothermy but simply make maintaining homeothermy easier. That is, that
>uninsulated< homeothermic animals existed at one time. Are you sure you agree
with this?

<<Although the "ground up" argument is not   
without problems, it is also appealing to me because it seems to   
eliminate at least two evolutionary steps required by the "trees down"   
theory--tree dwelling and parachuting.>>

The fatal problem with the ground up theory of flight origins is simply that
running doesn't generate enough energy long enough for a nearly wingless,
nearly featherless animal to become airborne. Gravity does. Powered flight is
the ultimate solution to the Falling Problem.