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Re: OCCAM'S RAZOR & THERIZINOSAURS
John V Jackson wrote:
> >> i): Hair/fur originating as developments from reptilian scales much
> >> the same lines as in pterosaurs and mammals, serving the joint purposes
> >> insulation, and drag for minimising fall damage and helping steerage
> >> 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
> >> downward movement, the capability to glide in simple table-mat style
> >> smoothly and inevitably develop. It is at this stage that aerodynamic
> >> features of individual feathers would become subject to evolutionary
> >> Note the tendency of feathers in flightless birds to move away from fully
> >> interlocking streamlined and sub-spatulate form, towards either
> >> 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
> >describe, _before_ developing into an organ of flight, [snip]
> I don't see how you could get that meaning from what I wrote! Paragraphs i
> & ii are successive stages.
Whichever. The same question still applies: if feathers evolved this way, then
how do you justify the statement that the presence of feathers necessarily
implies a flying ancestry?
-- Jon W.