Re: feather tracts

["Tim Williams" <twilliams_alpha@hotmail.com>]

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
phylogenetically 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




------------------------------------------------------------

Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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