Over the past few weeks you have seen a brief introduction to all of the interns, what we do, exciting visitors, and wonderful tours. Now, I think, it is time to jump into the rabbit hole, and see what the collection holds.
First, I should provide some background information about
most of the fossils we work with. The Mapes collection holds primarily fossil
cephalopods (ammonoids and nautiloids – the externally shelled ancestors of
squids and octopi). These fossils can come in any size from microscopic
(you will see this later) to extremely large (some can have external shell
diameters of 8+ feet). Modern Nautilus, shown below, are thought to be the
closest model for all of these extinct shelled organisms.
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Nautilus pompilius (left) and Allonautilus
scrobiculatus (right) – modern representatives of an externally shelled
cephalopod (image courtesy of
University of Washington). |
Nautiloids and ammonoids are revered for their shells and
the patterns you can find on them. These patterns – called sutures – represent
the contact point of dividing walls (septal walls – provide structural support
for the shell, does have some other minor functions) inside the shell with the
exterior shell body. These patterns cannot be seen on modern nautilus until the
outer layers of the shell have been worn away. One of the coolest things about
working with the Mapes collection is you can see the evolution of complex
sutures through time.
Sutures started out in the “nautiloid” form which is the
simplest pattern one can find on a shelled squid. Modern nautilus and its
ancestor nautiloids have retained this simple pattern throughout time.
Ammonoids, on the other hand, have not. They have developed an increasingly
complex suture pattern through time right until they went extinct in the
Cretaceous. From the “nautiloid” pattern, sutures developed first into a
“goniatitic” form (looks like waves or subsequent chevron folds) during the
mid-paleozoic. Then, the “ceratitic” forms developed in the later Paleozoic.
Both the goniatitic and ceratitic forms coexisted in the later Paleozoic. Once
you reach the Mesozoic, the suture patterns become their most extreme in the
“ammonitic” form during the cretaceous. Below you can see a generalized
schematic of each type with a corresponding picture taken from specimens in the
Mapes collection. Keep in mind, these types are more of a continuum than a
“four types fits all” scheme. Not every ammonoid will fall into one of these
categories, and will sometimes fall somewhere in between.
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Generalized schematic of suture types with corresponding images of real specimens within the Mapes Collection. |
The Mapes Collection can tell amazing stories, like the
sutures above. You can also see the diversity in ammonoid shapes that have
arisen through time.
One of the most uniquely shaped groups in the world of
ammonites are the heteromorphs. These ammonites are not your typical spiral
shape. Some have long extending hooks detached from the main shell (if you want an example of hooks on ammonite shells click
here). Some don’t even resemble an ammonite at all.
For example, one of the interns had this Cretaceous aged torticone (a turreted
spiral shape) ammonite in one of their cabinets.
As you can see, the Mapes Collection holds a wide array of
unique stories that aren’t just limited to cephalopods. The collection houses
more than we thought possible. In the past week we have found cephalopods (by
the ton in ammonoids, nautiloids, and some coleoids (modern squids with
internalized shells), vertebrates, bivalves (clams), brachiopods (they are
similar in appearance to clams but not even closely related), even some of the
more mysterious groups like conularids (there is no way to describe them, no
one knows where they belong, click
here for more on conularids), and scaphopods (tusk-shells).
Our task, as described in an earlier post, is to “rehouse,
conserve, and catalog” the Mapes Collection. This is easier said than done. As
you have seen, the collection houses just about every type of organism
imaginable from a vast array of locations. Over the past few weeks we have
sorted by locality, changed trays, assigned catalog numbers, and digitally
linked any associated information for more than 2,000 catalog numbers (keep in
mind 1 catalog number can hold anywhere from 1 specimen to upwards of 500
depending on the tray). We are aimed to pass the half way mark this week to
meet our goal of 5,000 lot numbers (I think this totals about 27 cabinets).
You have seen some of the wonders this collection can hold.
However, for each wonder there are a host of surprises and problems that can
arise in our line of work. This week we were introduced to new methods of
cataloging as we encountered unexpected microscope slides hosting ammonitella
(embryonic stage ammonoids – more commonly known among the interns as tiny baby
ammonites).
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Microscope slide hosting numerous ammonitella. |
There have also been severe cases of pyrite disease.
Pyrite disease is where the mineral pyrite (FeS2), or potentially similar
minerals, form within the bone, shell, or other material of the fossil. If
incorporated, pyrite can oxidize (FeSO4 – Iron sulfate). Iron sulfate is much
larger in volume than the original material and during crystal growth can cause
the specimen to fracture. This is especially common in more humid conditions.
The end result is what appears to be a large pile of cigarette ash with no
specimen to be found. Shown below is a picture of a pyrite diseased specimen
found in one of our cabinets.
However, pyrite does have its redeeming qualities. All of
the problems and unexpected surprises within the collections become worth the
effort when you find a true gem like the one below. This is a pyritized
ammonoid. Pyritization is not the same as pyrite disease. Pyrite has replaced
the original shell material and does not oxidize. This specimen also depicts
some beautiful goniatitic sutures.
Unusual localities have been a reoccurring theme this week.
For example, one of the interns ran across a lagerstätte. For those of you who
don’t know, a lagerstätte (lagerstätten – plural) is a sedimentary deposit that
exhibits fossils with truly extraordinary preservation. This preservation can
include soft tissues and other fragile pieces of anatomy. Below are some
pictures of preserved original orthoconic nautiloid shell material from the
Buckhorn Asphalt Quarry deposit. This material is impregnated with
hydrocarbons (oil) preventing the destruction of the original aragonitic shell
material. For some context, finding a lagerstätte is equivalent to finding a
diamond in the rough. They are very rare, and those that do exist provide us
with a fortune in scientific insights into what some of these organisms actually
looked like with all preserved soft parts (not typically found in your everyday
fossil bed), behaved, and where they lived.
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Orthoconic (straight) nautiloid with original shell material from the Buckhorn Asphalt Quarry. |
Granted, all this work isn’t without the typical mid-week
break. This week we went on a tour of the herpetology departmental collections.
Let me tell you, some weird things are housed there. I am going to let the
pictures speak for themselves here rather than provide narration. Well…maybe
some so you know what you are looking at.
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Talk about an unusual
find…an approximately 4,000-year-old gecko. This gecko was found during an
archaeology dig in Egypt. It was thought to be an accident as animals were not
usually buried within the mummy wrappings. Though animals were typically buried
with the mummies within the tombs. |
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Your typical crocodile hide with skull.
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Did I forget to
mention they have Komodo Dragons? |
Don’t forget the live
animals too J. These tortoises seemed content basking in the
light of their heat lamp.
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Sorry, I forgot what
kind of snake this was… |
Oh, and have you ever seen a rattlesnake penis?
Now you have.
As I have no real sign off ideas, I will leave you with one
last image that I believe summarizes our goal for this collection. Be
forewarned, it may not be what you expect.