color pattern source material

[Flyinggoat@aol.com]

I've been following up on various threads started by the color repost of
Neil's, and this is something I thought people on the list might be
interested in.

Glen and I have been talking about color off-line.  He is primarily
interested in color in Gastropods and is not on the dinosaur list.  If you
wish to respond to him, I have included an e-mail address for him.  He says
it's ok.
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>From: gg533291@oak.cats.ohiou.edu (Glen Earl Gardner)
To: Flyinggoat@aol.com

>Hi Glen,
>  I wonder if we've got any plant material that color has been retained on.
> We know color of plants almost as a given.  Would that be a better place to
>start looking for color than on things we don't know what color they were?
>
>Betty Cunningham(Flyinggoat@aol.com)

Hello Betty..

Boy...that is a good question....  We do know that modern cephalopods have
color. In fact roughly 95% of all modern shallow warer animals have some kind
of
coloration. Has it always been this way? Why? Color patterns have been
described
for a number of fossil molluscan forms, and modern Molluscs have an
incredible
variety in coloration. So, we do know that color is important to Molluscs,
and
that there are a few hints that color patterns have come and gone and
returned
(at least in cephalopods) over the ages.  These are the kind of questions
we have about color, and we need to study these things BECAUSE we don't know
what color they were, or how ancient cephalopods compare to their modern
descendants.  We need to find out, so that we can get a better understanding
of
how these animals lived.

I don't know much about plants, and I don't know of any occurence of
preserved
fossil color in plants. There might not be any at all.
I have seen mesozoic lignite in South Dakota that you might as well call
buried
 wood....  I don't recall seeing any leafy material (or flowers for that
matter).
..  I think that the conditions for the preservation of organic pigments are
so
 unusual that, until recently, color in fossil forms has been largely
overlooked
 by the paleontological community...

But, back to plants..  

We have a couple of paleobotanists here at O.U., and in my wanderings around
our
"archives", I have seen most of the stuff that they have.
I have not seen anything that could be immediately interpreted as "color" on
fossil plant material..  There is plenty of preserved organic material...A
good
chemist might be able dig a little deeper....  A friend of mine once told me
that there is a considerable amount of organic material preserved in
petroleum,
(lipids) but I don't have the facts on that...

It seems to me that the conditions that lead to really good preservation of
plant material (pete bogs & coal swamps) tend to destroy delicate pigments
such
as melanin (do plants use melanin as a pigment?), or chlorophyll and remove
the components.  

Among marine invertebrates, the conditions that lead to the preservation of
melanin might include:

1) Rapid burial in a very fine material (fine enough to prevent the
circulation
of fluids) leading to a very fine-grained matrix (or at least some means of
preventing the circulation of fluids).

2) Normal Ph, eH ... That, is neither reducing nor oxidizing conditions.. 

In the case of wetlands, bogs and swamps, they tend to have conditions that
are either
strongly oxidizing or strongly reducing, and have a considerable amount of
water moving through the sediments... Even though the plant material is not
being broken down by bacteria, the more delicate components would probably be
altered chemically and/or removed rather quickly. So coal & peat deposits are
probably a bad place to look for color.

I do know that melanin and chlorophyll are VERY delicate...Some forms of
melanin are water soluble, and melanin will soon begin to fade when exposed
to
sunlight, and chlorophyll breaks down VERY, VERY quickly when exposed to
sunlight.

So, if you are going to find coloration on fossil plants, you are going to
end
up looking for plant fossils in places that you might not otherwise consider.

You will also need to DIG ....  

On the ammonoids that I am working with, you have to extract the specimens
from
the limestone bedrock, well away from the weathered surface.  Specimens that
 have weathered out, and are exposed to the environment rarely have any trace
 of color patterns remaining.  Any weathering at all seems to destroy the
 color patterns...

I know a place in Wyoming...Miocene in age (I think)... It is a klinker bed
above a coal seam that had burned underground ages ago...  It was a very fine
mudstone that was thoroughly baked by the heat of the burning coal... I
didn't
get to spend much time with it, but it is absolutely loaded with impressions
of
leaves, twigs and assorted plant debris... I am told that further south
(around
Dinosaur Colo.) that these same beds (not baked) yield leaves, flowers, and 
insects. They are often preserved as carbon films.  I wonder if one might
find
traces of pigments preserved in places like this??

You know, specimens of cuttlefish found in the Solenhoffen limestone have
their
ink sacks preserved so well that the "ink" can be rehydrated...the melanin
is very well preserved... So organic pigments do get preserved.... we just
need
to start looking at the problem a little differently than we have in the
past....

The thing that is important about color is that it can be interpreted (at
least
in theory) in terms of how & where a life form exixts.

Are you working on color, or are you just interested in the subject?

I am working with color patterns on Triassic ammonoids as a graduate thesis.

C.U.  
--
Glen