Re: feather tracts

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

Ken Kinman wrote:

>     But those are mostly Cretaceous (i.e., very derived
> Johnny-come-latelies), including secondarily flightless forms.

I wouldn't regard _Microraptor_ has "very derived" - it looks a lot like
(but not exactly like) what I would expect of a pre-late Jurassic
maniraptoran on the line to _Archaeopteryx_ and modern birds.

And which forms are secondarily flightless?  _Caudipteryx_, just because it
has remiges formed into a wing?


>      I'm talking about Triassic and Early Jurassic, very primitive forms.

Forms of theropods or forms of birds?  If the latter, I wouldn't hold your
breath waiting for Triassic birds to turn up.  :-)


> 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.

I think you might be putting the cart before the horse.  Why couldn't
feathers have evolved for insulation and _then_ exapted for aerodynamicity?


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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