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Carl,
That is correct. After burial the proportions of the micro-surfaces change. We are talking in terms of light wavelenght (700 nanometers for red 400 nm for blue). Just some little deformation (some nanometers in that particular surface) is enough to change these physical properties. We can see the color pattern but not the former factual colour.
Patricio
----- Mensaje original -----
De: Carl Mehling <cosm@amnh.org>
Fecha: Martes, Junio 14, 2005 6:03 pm
Asunto: Re: paleonet Fossil Color
> Thanks Patricio. I was aware of the difference between pigment vs.
> structural color. But not to the degree you outlined - thanks! One
> question: When you say of the Messel beetles "could be not green
> but dark
> violoaceous" do you mean that the colors they show are not
> original or may
> not be original?
>
> -Carl
>
> At 11:48 AM 6/14/2005, you wrote:
>
> >Living organisms exhibit two main types of coloration: pigmentary
> and
> >structural colours. Probably you realise what is a pigmentary
> color. A
> >pigment, usually an organic component such as melanins (i.e.
> mammal’s skin
> >and hair), carotenoids (i.e. astaxanthin in crayfish), bilins
> (i.e.
> >bilverdin in bird eggs), quinines (i.e. echinoquinones in sea
> urchins),
> >give some coloration as ink do it in a paper. Usually such
> pigments are in
> >specific cells (chromatophores, melanophores, etc) scattered in
> particular
> >tissues (dermis, epidermis, etc.).<?xml:namespace prefix = o ns =
> >"urn:schemas-microsoft-com:office:office" />
> >
> >On the other hand, structural colours are due to the microscopic
> features
> >of the physical surfaces. These include interference,
> diffraction,
> >reflection, refraction, iridescence… A very famous structural
> colour is
> >the Tyndall blue (a similar phenomena to the Rayleigh scattering
> observed
> >in Earth’s atmosphere). Nacre exhibits iridescent structural colour.
> >
> >Animals combine any of such structural colours with pigments in a
> plethora
> >of visual effects not only in the same estructure but also
> different parts
> >of the organism are coloured using differnt "technologies".
> Usually,
> >black or brownish colours are usually pigmentaries. However,
> white colour
> >rarely is pygmentary .
> >
> >Most of the pigments may well decay after death. However
> structural
> >colours may be easily preserved, although as such colours depends
> of the
> >very precise length of the micro-details of the surface (in terms
> of
> >fraction of wavelength of incident light) the resulting colour
> after
> >fossilization should be very different. For example, the
> beautiful
> >metallic green of some of the Lucanids beetles from Messel, could
> be not
> >green but dark violoaceous (for example). Other examples of
> structural
> >coloration are the brownish pattern that some fossil moths and
> butterflies
> >exhibit in their wings.
> >
> >
> >
> >Jere Lipps proposes a couple of Ph.D. dissertation on colours.
> Possible
> >candidates: don’t forget to use SEM to check the surfaces at
> wave length
> >scale. Structural colours, although not visible today should be
> preserved
> >in some way…
> >
> >
> >
> >Cheers,
> >
> >
> >
> >Patricio Domínguez
> >
> >
> >
> >----- Mensaje original -----
> >
> >De: "Jere H. Lipps" <jlipps@berkeley.edu>
> >
> >Fecha: Martes, Junio 14, 2005 8:23 am
> >
> >Asunto: Re: paleonet Fossil Color
> >
> > > We need some studies on the taphonomy of color.
> > >
> > > My impression is that color is preserved in certain circumstances,
> > > including species-specific aspects. Organic rich and/or anoxic
> > > deposits seem to preserve color sometimes, whereas others (oxic?)
> > > do not. Certain gastropods seem to show more color whereas
> > > others have no color when alive. So a taphonomic review would run
> > > the entire gamut from living through fossilization to collection
> > > by paleontologists (do we pick out the colored ones more than
> > > others?).
> > > Probably a couple of Ph.D dissertations in this, at least. Maybe
> > > some have been done, but more could be done I'd bet.
> > >
> > > Jere
>
> Carl Mehling
> Fossil Amphibian, Reptile, and Bird Collections
> Division of Paleontology
> American Museum of Natural History
> Central Park West @79th Street
> New York, NY 10024
> (212) 769-5849
> Fax: (212) 769-5842
> cosm@amnh.org
>
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