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Re: OCCAM'S RAZOR & THERIZINOSAURS



John V Jackson wrote:

> --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.
>

It does.  Now the next question: if feathers evolved in either of the ways you
describe, _before_ developing into an organ of flight, then how do you justify
the statement that presence of feathers necessarily implies a _flying_ ancestry?

-- Jon W.