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Re: OCCAM'S RAZOR & THERIZINOSAURS



--Original Message--  From: Jonathon Woolf   Date: 02 August 1998 19:58
Subject: Re: OCCAM'S RAZOR & THERIZINOSAURS

>Um, could you answer a question for me, please?  If the presence of
feathers
>necessitates a flying ancestry, then where did feathers first come from,
and
>why?
>
>-- Jon W.


i):  Hair/fur originating as developments from reptilian scales much along
the same lines as in pterosaurs and mammals, serving the joint purposes of
insulation, and drag for minimising fall damage and helping steerage during
leaps.

ii):  Simple hair structures becoming progressively more complex and thus
increasing drag/weight ratio, eventually to the point where the
proto-feathers align horizontally when the creature is in flying squirrel
pose.  With tail and arm feathers in this configuration, optimised to oppose
downward movement, the capability to glide in simple table-mat style would
smoothly and inevitably develop.  It is at this stage that aerodynamic
features of individual feathers would become subject to evolutionary tuning.


Note the tendency of feathers in flightless birds to move away from fully
interlocking streamlined and sub-spatulate form, towards either "explosive"
or longer and more hairlike forms, depending on usage.


Um, I hope that helps.


John V Jackson