#Fossil question
14 messages in this thread
While nosing around the math section of this forum, I noticed the heavy volume
of messages about fossils, and although it may be slightly absurd, I'd like to
try to take advantage of your collective expertise by posing a question that
probably cannot be answered by modem.
On a whim, I bought a fossil for my girlfriend. I saw it in a store; it was
pretty; it cost only nine bucks. When I got home, however, it occurred to me
that it might be fake, and it's been sitting here on my desk ever since while I
wonder whether to gift wrap it or return it.
What I propose to do, as silly as it may be, is describe the thing as best I
can in the hopes that someone can tell me whether it's real.
The object is labeled, "Green River, WY, Eocene, 50+ million years old." It's a
flat block about 7 x 3 x 1/2 inch in size, shaped much like a thick rectangular
tile, of a stony material that looks very much like plaster, except that it's
slightly grayer or browner in color and has small flecks of a gray substance in
it (which may only be dirt in the pores). The edges (1/2" dimension) were cut
with a saw, and are smooth, and have few flecks; the top and bottom is rough
and porous, as if the thing was split, not sawed, to form its large faces.
Looking at any edge from the side, a narrow stripe of yellow-brown is visible
all the way around, so the whole thing gives the effect of a peanut butter
sandwich on crustless white bread that has been pressed under a weight and
squashed until the peanut butter is visible only as a thin brown line around
the edges.
The fossil, if that is what it is, is a four inch fish on the top flat surface.
It's yellow-brown, like the stripe, whereas the substrate is off white. It
consists mostly of bones, including part of the spine and some fine bones that
are atached more or less perpendicularly to the spine, but there are also
brownish-yellow stains on the substrate where the head, tail, and part of the
body were. These stains look to me more like organic matter that leached from
the decomposing fish into the substrate than minerals that accumulated in the
tissues of the fish. There are also some "fossilized" yellow-brown bits along
the perimeter of what I take to have been the most ventral surface of the fish
before it was squashed into a pancake, as though it had scaly armor along its
belly. These plates or bits are almost as big as the vertebrae. The two biggest
glops of fossilized stuff are at the forward end of the creature's snout. In
addition to the brown/yellow bits of bone and other material, and the
stain-like leaching, there is also an impression, a sort of negative body cast,
of the tail and part of the head. The yellow-brown fossilized bits (other than
the stain) are chunks of material, and they protrude upward from the substrate.
The reasons for my doubts about the thing's authenticity are (1) the bones
appear to be of an entirely different material from the substrate, (2) the
yellow-brown material does not look particularly like a mineral, (3) I think I
might be able to manufacture an object very much like this one by allowing a
large sardine to decompose on a plaster slab. Why anyone would bother to do
such a thing, for nine dollars, I have no idea…
Thanks. I hope this isn't too ridiculous.
— Rob
P.S. Are there are good sites for fossils close to New York City?
Dear Rob,
Your question isn't ridiculous. I think it's the real thing. It's a key…..
Though I don't consider myself a fossil expert, I do have a small collection of
fossils I've amassed from all over. One of the most ubiquitous fossil
specimens sold everywhere, be it here in the USA or in the Orient or in Europe
is the Knightia species of fossil fish that are found in the thousands in
Kemmerer, Wyoming and adjacent areas. There are even commercial fish quarries
(Waricks ?) that let you dig for your own fossils. As I recall, most of the
fishes and rays are dated at about 30 million Eocene from the Green River
formation. I've picked up nice genuine knightias for anywhere from 4-25
dollars. There are also plaster casts that Nature Company and many others
carry that are pretty close appearing to the real thing…but the plaster
replicas don't have any stratification of the plaster looking edgewise. So,
I'd bet that your fossil fish is probably the real thing. Sometimes, you see
huge plates a yard across with a thousand of these knightia fishes in what's
called mass kills. Maybe the salinity or turbidity of the water abruptly
changed, volcanic acid rain, or the O2 content deteriorated, or there was a
drying period…a flood, whatever…
Another ubiquitous fossil sold by the thousands everywhere (that you could
purchase with just a little effort) is the fossil trilobite Elrathia kingi from
Delta, Utah, again sold often for anywhere from 3-30 dollars depending on the
size and quality. These date back to the Cambrian period 550 million years
back to a time life forms finally became complex enough with enough hard parts
to leave a significant fossil. Unlike your fish that is still recognizable as
being similar to other fishes you see today, the Trilobites as a group,
survived hundreds of millions of years, only to finally go extinct and
disappear completely well before the first dinosaurs appeared. So this 3
dollar fossil provides a spring-board into Evolution as a Fact and not just
someones theory. HOLD IT IN YOUR HANDS! Extinction. Punctuated
Equilibrium… those are the key ideas that takes us beyond Darwin.
I think it's sobering to think that we're descended from the very first life
forms that evolved on good ole Mother Earth that can claim continuous progenies
thru time til the present. When those trilobites and even those Knightias were
swimming, somewhere our ancestors were alive, too, evolving successfully (?)
and some of their off-springs surviving right up to the present time.
In some ways, whether a fossil specimen I have access to is a very well
executed replica of a real fossil I know exists or the genuine fossil itself
might often be moot. I do have some replicas of larger specimens I couldn't
otherwise afford or access for study. To me, the exciting thing is that
fossilization occurs at all, and that this "accidental" process provides
undeniable evidence of life in the past, complex and different from today,
providing key answers to questions about evolution.
There's a lot of popular science books on fossils and evolution, but the ones
I've must enjoyed includes Niles Eldredge's LIFE PULSE, and Stephen J.
Gould's WONDERFUL LIFE, both very readable for the interested lay person.
Me, my true passion is meteorites. More ancient… 4.6 billion years old and
even older…
-Joseph from Honolulu
Hi Joseph,
Thanks a million for your very informative and enjoyable answer. The store
where I bought my knightia had many more of the same kind in various sizes,
including a few larger plates with several fish together (although nothing so
big as a yard across), which probably strengthens your identification, I think.
The store also had baskets of trilobites, nautiluses, and sharks teeth. Lots of
each, but that was pretty much it. They all appealed to me for the reasons you
describe but I thought my girlfriend would like the fish because it was so
pretty. She makes pottery and loves ceramics; this particular knightia died in
a remarkably striking pose, and it's positioned on its rock as if an artist put
it there, and the rock itself has a color and texture which I knew would appeal
to her.
I've read all (or nearly all) of Gould's non-academic books, including
Wonderful Life; in fact, I let my subscription to Natural History drag on for
years, even though I rarely read most of the magazine, because of his column.
I like your comments about evolution; they made me pick up the knightia and
ponder it with the thoughts you describe. I also liked Dawkins' book (is the
title the Blind Watchmaker?), which I think has a wonderful passage in which he
describes millions of seeds blowing down from trees and he says something to
the effect, "It's raining DNA; it's raining computer programs." (Well of
course I liked it; I'm a programmer.) Also, Darwin's Natural Selection, in
case you haven't read it, is an extraordinarily interesting book even today.
One thing that struck me about the fossils in the store (the first time I had
ever seen any outside a museum or handled one) was how fully complex the
animals were. Nothing obviously "primitive" about them to non-expert eyes.
But mainly I was struck by the huge *amount* of life there has been on this
planet! So much that baskets of fossils turn up for a few dollars a piece. The
fantastic prodigality of nature, that makes objects so delicate and
extraordinary by the quintillions, each cell of which is more complex than the
most elaborate computer or aircraft carrier, and then drops them from trees,
uses them as food, as fertilizer, wastes them, squanders them, purposely
disintegrates them so it can put them together again. The sheer mass of all us
creatures that have been past and present, so many of us that the crusts and
dusts of our bodies cover the ocean floors and fill cubic miles of sediments
across continents.
— Rob
Dear Rob,
"But mainly I was struck by the huge *amount* of life there has been on this
planet! So much that baskets of fossils turn up for a few dollars a piece. The
fantastic prodigality of nature, that makes objects so delicate and
extraordinary by the quintillions, each cell of which is more complex than the
most elaborate computer or aircraft carrier, and then drops them from trees,
uses them as food, as fertilizer, wastes them, squanders them, purposely
disintegrates them so it can put them together again. The sheer mass of all us
creatures that have been past and present, so many of us that the crusts and
dusts of our bodies cover the ocean floors and fill cubic miles of sediments
across continents.
— Rob "
That was beautiful! From your familiarity with Dawkin's BLIND WATCHMAKER, and
Stephen Gould's series of popular books, I've really misjudged your familiarity
with this subject of Evolution. Yes, I've enjoyed reading all of those you
mention and continue to also subscribe to Natural History. From the flavor of
your initial note I thought you might need just a nudge of encouragement to
leap from what I took as your casual interest in your girlfriend's gift!
You're very lucky to be in New York. Hawaii's definitely got it's pluses, but
there's not much here to stimulate interest in Paleontology….
Take care,
Joseph
Joseph,
I've tried uploading the following message several times, but each time, I had
to delete it because I repeatedly forgot to format it properly. I've lost
track of whether I finally did leave it uploaded or not, so I'm uploading it
again. If this is a repetition I apologize.
Thank you indeed for the compliment. And you were exactly right when you
inferred from my first message that I was completely ignorant of the subject,
because I was; it's just that the subject was fossils, not popular books about
evolution.
And you did make me more interested in fossils, as a matter of fact, because
you made me connect the object with things I knew intellectually.
You complained in your last message about the state of paleontology in your
neck of the woods. I know even less about geology than I do about fossils, but
I imagine the problem is related to the relative scarcity of fossils in places
that come out of volcanos. Still, you wouldn't want to be in New York City
right now, believe me. It's so hot that you could make burnt toast by laying
bread on the sidewalk, and it would come out soggy from the humidity.
— Rob
Hi, Rob–
Welcome to the forum/section!
As best I can remember my Wyoming fish fossil (likely from the same formation)
while away from home, yours sounds right. I got mine from a fossils dealer at
the big Denver gem/mineral/fossil shows (September each year) complex, where
there are enough knowledgeable collectors (not me, where fossils are
concerned!) that a seller of cheap fakes could not easily prosper (a fake good
enough to fool experts would be another matter, but that needs a lot more than
$9 to justify the effort and risk). It is such a common fossil (at least in the
one area), and so readily available at similar prices, that there seems little
extra profit in making even cheap fakes of it.
The appearance of the bones makes me suspect a preservative has been used on
them – they might be fragile.
–Doug
Doug,
Thanks for the welcome.
A preservative! Such a thing never occurred to me. I think of rocks as pretty
tough things and never thought a fossil might be fragile.
Why are preservatives necessary with some fossils but not others?
— Rob
Hi, Rob–
I am not really sure what makes some fossils more delicate, but I can hazard
some guesses.
Which minerals replaced the tissues of the organism are likely a critical
factor. Some mineral specimens can change or disintegrate if they are exposed
to the wrong temperature and humidity regimes. Some form in dry conditions,
and absorb moisture to change to something else (and often lose their
structural integrity) if given a chance; others form with water in their
structure and lose it if the climate becomes too dry. Fossils are surely
subject to similar considerations.
A rock forms as a solid unit, where a fossil may have the same mineral(s)
following delicate structures of a living thing, including air spaces, not
following their natural interlocking pattern, and thus not interlocking as
tightly (the crystal structure is the same, but how the individual crystals
interlock is likely not). Traces of other minerals or original materials of
the living thing may weaken the bonds between crystals (compare a brick wall
built with mortar and one built with oil between the bricks).
Consider a brick wall, and then consider a car made of bricks that must follow
the contours of an ordinary car (instead of all horizontal) – I can pile bricks
under and inside the car, but I still do not expect it to be as tough as the
wall. Also, if I pound them both, the wall can lose some chips and still be
well qualified as a wall, but a few bricks shifting may degrade the car shape
considerably, keeping the vague outline intact but losing the detail one wanted
to keep in this car "fossil".
–Doug
Rob – I just recently returned from Wyoming with about 300lbs of exactly what
you have described. I can vouch for the authenticity of the fossil fish. They
are indeed real, are indeed close to 50 million years old and the $9 you paid
for a 4 inch fish is a good deal ( you weren't ripped off).
More than likely the fish is one of the genus Knightia, as they are the most
common found in the Eocene lake deposits and fall within the size you
mentioned. The darker bits and pieces you see, the vertebrae ribs and gill
plates, are not permineralized, that is, they are the original material more or
less. The substrate or matrix is calcium carbonate, or limestone, that is very
easily split. The dark stripe you see midway through the thickness of the slab
is indicative of another fossil layer.
It should be noted that *some* fossil fish from Utah and Wyoming have been
re-touched, having some details painted in. This is more frequently seen in
some of the larger specimens which were damaged in preparation.
As for the preservative issue that Doug raised, surprisingly nearly all
vertebrate fossils required the use of some consolidating preservative. What
you see on the Knightia slab is in part a very thin carbon film. this film
will definitely pop loose over time due to changes in temperature and humidity.
More than likely, Krylon or a similar artist's fixative (used on charcoals etc)
was sprayed on. Or perhaps Glyptol or Butvar was used on the bones. While we
tend to view dinosaur bones as massive, strong and permanent, that is rarely
the case except for heavily silicified specimens. The bones I've collected
from the late Cretaceous in Montana and Alberta were poorly mineralized, and
needed heavy doses of a consolidant to hold them together.
Regards,….and give that fish to a lady!
Michael
Michael,
Thanks tremendously for what is obviously the fruit of a great deal of
experience.
I didn't know until today that fossils often or ever consist of original
material; I had thought that by definition, a fossil is made of stone.
Some of the other Knightia at the store where I bought this one had obviously
been painted with something like fixative, but glossy and thicker; in a few
cases, it was daubed on in the shape of a brush stroke. But mine, if it was so
treated, was handled in a subtler way.
Thanks again.
— Rob
Michael..
You mention consolidant.. I have some Cretaceous fossil wood that is very
fragile, crumbly, and I think the solution for its preservation would be a
penetrating consolidant. Perhaps you could make a recommendation?? Thanks..
Bill
From what I have read and heard in my paleo resources, BUTVAR-76 (Polyvinyl
butyral) is the most preferred consolidant. It is in solution with either
alcohol or acetone. Another choice is PVA (polyvinyl acetate). Some grades of
PVA are soluble in water, an example is Elmer's tm Glue-All. A 1:4 solution of
Elmers:Water works real well. And apparently, among some folks, superglue
(generic) has found favor. I haven't found a reasonable price for it yet.
I would be happy to post to the Library a more detailed discussion of
consolidants, glues, fillers and other prep items if you would like.
If I were prepping the wood, I would use the 1:4 Elmers, brushing it on gently
allowing the specimen to absorb the glue as I proceeded. Care must be taken
though that the specimen is not soluble in water. If it is then a different
consolidant needs to be used.
BTW, I have used the Elmers on a 4ft long whale jaw that was extremely punky,
porous and fragile. It is now much stronger and able to be handled.
Michael
Thanks Michael..
This wood is not water soluble, so I think it will accept the PVA mix. It will
be interesting (to me, anyway) to see how this works out.
I would appreciate the listing of consolidants if you'd upload to the Lib.
Will let you know results…
Bill