Re: Longisquama "feathers"

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

David Peters (davidrpeters@earthlink.net) wrote:

<What I don't understand is their detached nature. Are the frills of Sphenodon
and Iguana shed in bits and pieces?>

  The "frills" of tuataras and iguanians are comprised of osteocones or
hardened, scleral tissues surrounded by keratin, and do not shed with the skin
to the bets of my knowledge. I've witnessed a few skins shed, and they do tend
to split down the back, and most lizards either flake the skin off, or pull off
large chunks of shedding dermis at once.

  The structures, as Tim wrote, in *Longisquama* represent one side of
impressions so far unrepresented anywhere else on the slab, and do not indicate
one way or another, i.e., are agnostic on the topic of whether there were two
rows or one, or maybe five. Thus we can't really argue there was a single row,
anymore than Martin and his student can argue there was one. Until this is
provded by evidence, making a model with the romantic idea of paired aerofoils
formed from "frond"-shaped "scales" we have NO idea what they may have been
used for. Unlike all other lepidosauromorphans with aerofoil-adapted bodies,
these structures do not arise as extensions of the ribs or uncinate-like
elements, and thus they remain outside of our knowledge base from what animals
can do.

  Cheers,

Jaime A. Headden

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


                
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