Re: Longisquama shed plumes

["Jaime A. Headden" <qilongia@yahoo.com>]

Dave Peters (davidrpeters@earthlink.net) wrote:

<Any matrix that perfectly preserves the exoskeletons of insects and the scales
of reptiles, as has been demonstrated, might also preserve the shed skin of
Longisquama plumes. Not sure what the test would be to determine whether the
shed pieces included the deeper layers or not.>

  This is all assuming of course that these plumes are in any way shed reptile
skin, scales, or whatnot. They have been argued before to be accidental
occurences. The lack of preservation of even partial reptile skins as fossils
separate from their bearers is as telling as that isolated features are RARE
and designed to drop off, such that feathers would be more favorable finds as
isolated structures than shed skins, usually released on dry, rough areas the
reptile can rub against. Even so, isolated feathers remain more numerous than
isolated scales or skin fragments from any reptile, all of them deriving from
*Longisquama* plumes, apparently. As for the finesse of preservation, the
holotype skeleton of *Longisquama* is not even complete and hardly
fine-detailed, with the large features of the plumes representing details only
as fine as the bones themselves. And is it not surprising that the bases of the
plumes are never clear? This might even be expected if there were a layer of
mud beneath the animal overlying the plumes, if the fossils were not already
attached, such as might happen if the animal were to have died and been buried
nearly on top of these structures, never having borne them. The neck squamation
and the brachial "parafeathers" may very well be natural and part of the
animal, but the plumes may not be.

  Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


                
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