Re: feather tracts (and protoscutes)

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

Ken Kinman wrote:

> In the Triassic there were probably many different structures
> that were intermediate between feathers and scutes.  Longisquama is "hard
> evidence" of such structures in my opinion.  Such structures probably
> evolved many different times among archosauromorphs, so calling those of
> Longisquama by the term "feathers" could be very misleading.

Indeed.

Putative dorsal skin flaps (somewhat squarish in shape) have been reported
for _Cosesaurus_, a prolacertiform like _Longisquama_.


> [snip] saying that they have nothing to do with feathers at all is also
> somewhat misleading.  The truth is probably somewhere in between.

_Longisquama_'s superficially feather-like things (which, AFAIK, have not
been convincingly shown to be bilaterally paired) probably have as much
relevance to the origin of bird feathers as the dorsal scutes of
_Ceratosaurus_.


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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