Re: Origin of feathers

["John V Jackson" <jjackson@interalpha.co.uk>]

-----Original Message--- From: Dinogeorge Date: 10 April 1998 09:38

>"Need" of course cannot provoke the evolution of a structure that fills the
>need; this is elementary.

ok.

>The paper on feathers
>for sulfur excretion implies there is a need for animals to excrete excess
>sulfur, and suggests that pre-feathers could serve as a mechanism for this.
>The desired immediacy of "cause" is present in this hypothesis, whereas it
is
>almost always absent in other hypotheses for the appearance of
pre-feathers. .

The benefit would be immediate in my skin-friction drag senario, surely?

 I'm moving towards the notion that fur/feathers for drag are initially
exploited mostly on the tail, to enhance stability of orientation.  ( I just
saw a prog about Pine Martens, whose body plan mimics squirrels.  I've also
been watching squirrels' gait, but they move too quickly for ease of
observation.  [Perhaps if we had some way of slowing them down?  A sequence
of cameras and trip wires, perhaps?!]  Though squirrels almost never walk on
the ground if they are actually "going anywhere", they, like martens, do
walk to adjust their position by a few inches.  I'm fairly sure squirrels
walk very quickly along the top of narrow fences.)

>so I like it. Meanwhile, we're nowhere near proving any of this, of course,
>and I'm quite sure we never will be.

You never know though.  However for me the aim is to convince myself, and
I'm far from doing that with feathers yet.

JJ