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More on archeo feathers



longrich@phoenix.Princeton.EDU wrote:

>It seems to me, racking my brain to remember bird carcasses I have
>found, that the wing and tail feathers are the last to go in
>decomposition. I don't know if Archaeopteryx was buried soon after death
>or found a more roundabout way to the ocean, but the birds I recall retain
>their tail and wing feathers long after the body feathers are falling off,
>for whatever reason. I'm curious about whether any scale imprints have
>been found in the Solnholfen, however. If the preservational conditions
>are that good, have any scale impressions been found on Compsognathus or
>Archaeopteryx?

Yep bird feathers do 'drop off' in the order you described however the time
aspect of the decay processes is crucial.  I have a paper that is coming
out in Palaios on the taphonomy of birds and an important point is that
skeletal disarticulation can and does occur even if the majority of
feathers are in place.  My experiments provide a math. model for estimation
of decay time from skeletal disariculation.  It shows ( and I can remember
the exact figure off hand but it was in the order of a week to 2 for the
most disarticulated archaeo specimen) there is not enough time for all the
feathers to have become loose and disappeared.
Scale impressions follow the same argument as mammalian hair - they are
also alpha keratin - so refer to my previous post as to why it does not
preserve.

>>The only plausible explanation from a taphonomic point
>> of view is that they weren't there to preserve in the first place.
>
>        This would mean that either Archaeopteryx lost its
>contour feathers, or that Confuciusornis developed them separately from
>modern birds. 

No the most parsimonious scenario is that archeo did not have BODY contour
feathers (primitive condition) and they evolved later (Confuciusornis is
younger by about 10-15 million years - a long enough time period for
anything to evolve in!).  This of course is an untestable theory (see
previous posting) and I would not adovcate such a theory in the sci.
literature but it does fit the facts.

Regards
PG