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Re: feather tracts


Tim,
    But those are mostly Cretaceous (i.e., very derived
Johnny-come-latelies), including secondarily flightless forms.
     I'm talking about Triassic and Early Jurassic, very primitive forms.
Once feathers were exapted for insulation, there would then have been a
tendency to develop a more scattered pattern on the body, especially as they
spread ventrally.
             -----Cheers,   Ken
******************************************************

From: "Tim Williams" <twilliams_alpha@hotmail.com>
To: kinman@hotmail.com, dinsoaur@usc.edu
Subject: Re: feather tracts
Date: Wed, 11 Jul 2001 15:42:01 -0500


Ken Kinman wrote:

    If feathers had originally evolved for insulation (of the body and/or
eggs), they would have been more likely to have had a more scattered
distribution (as in the hair of mammals).


It was my understanding that in all non-avian feathered theropods, the
feathers (proto-feathers, dino-fuzz, macerated collagen fibres, whatever
one may like to call them) were distributed over most the body.  Or, at the
very least, no part of the body is preferentially feathered in the diverse
array of feathered theropods.


P.S.  If feathers began on the other end (head) of  dinosaurs and spread
backwards, then perhaps display may have been a more likely original
function.


But there is no evidence for this.  Of course, at a later stage, the
feathers on the tail and forelimbs did become selectively elaborated
(_Protarchaeopteryx_, _Caudipteryx_, birds) into flight feathers.  But, at
the non-aerodynamic and insulatory stage of feathery evolution, most if the
entire body was probably covered.


Tim


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