I. Unaltered

    A. Unaltered soft parts:
                    (sealed from environment)

               i. frozen
               ii. amber
              iii. petroleum
              iv. desiccation
               v. pickled
 

    B. Unaltered hard parts:
                   original composition

most stable

        proteinaceous organics
                chitino-phosphate
                        silica
                                calcite
                                        aragonite
                                                cutilce & orther organics
 least stable

II. Altered:
 

    A. Altered Soft parts

        i.  Tissue replaced by a mineral
             (Burgess Shale example)

        ii. Carbonization: distillation of all volatile
                   elements, leaving only a carbon film.
 
 

    B. Altered Hard parts

        i. Permineralization:  filling of pore space by minerals
                                                 dissoved in water

        ii. Replacement:  molecule by molecule
                                          exchange of minerals.
                                         (e.g., pyrite replacing calcite).

        iii. Recrystalization:  reorganization of
                                                molecules to a different mineral of
                                                the same composition.
                                                (e.g., aragonite to calcite, CaCO3).

        iv. Carbonization:  distillation of all volatile
                                             elements, leaving only a carbon film.
 
 
 
 
 

III. Indirect Evidence
 

    A. Molds & Casts

            i.  Mold:  an impression of plant or animal.

                            external: outside

                            internal: inside

           ii.  Cast:  a replica of the original skeleton
                             made by filling a mold.

          iii.  Steinkern:  sediment fill of original void
                                       space, (gastropod chamber fill).
 

    B. Trace Fossils:  evidence of the activity of organisms.

        • e.g. tracks, trails, burrows, boring, dwellings, feeding.

        • tells more about ecology than identity of maker.

        • not molds & casts.
 
 

    C. Coprolites:     fossil feces.

        • information about diet, ecology & behavior.
 
 

    D. Gastroliths:     fossil gizzard stones.
 

    E. Chemofossils: any chemical evidence of past life.

        • complex organic molecules (e.g. petroleum).

        •  isotopes: Carbon, Sulfur.

        • molecular paleontology (DNA)
 
 

    F. Pseudofossils: things that 'look' like fossils.

            examples
           • sedimentary structures,
           • concretions,
           • mineral deposits
           • "man-made artifacts and trash
 

Building Blocks of "Fossils":

Common Element (fundamental unit of chemistry).

Carbon = C Silicon = Si Iron = Fe

Oxygen = O Hydrogen = H Calcium = Ca

Sulfur = S

Carbonate = Calcium & Oxygen

Common Minerals:

Calcite: Calcium Carbonate (fizzes in HCl)

Quartz: Silicon Oxide (harder than glass)

Pyrite: Iron Sulfide (brassy)

Hematite: Iron Oxide (red or brown)

Graphite: Carbon (black)

Question #1 Identify these minerals that commonly preserve fossils.

Specimen 1A ___________________________Specimen 1E ___________________________

Specimen 1B ___________________________ Specimen 1F ___________________________

Specimen 1C ___________________________Specimen 1G ___________________________

Specimen 1D ___________________________
 
 

Question #`2. These brachiopods are from the Ordovician Period (~420 million years ago).

The skeleton of the brachiopod was originally composed of Calcite.

The skeletons of the these brachiopods are still composed of Calcite.

What is the kind of preservation?

Question#3. These ammonites are from the Cretaceous Period (~70 million years ago).

The skeleton of the brachiopod was originally composed of a kind of

Calcium Carbonate called Aragonite. The skeletons of the these

ammonites are still composed of Aragonite.

Take note of the "mother of pearl shimmer".

What is the kind of preservation?

Question#4. These corals are from the Devonian Period (~350 million years ago).

The skeleton of the coral was originally composed of a kind of

Calcite. The skeletons of the gray specimens are still Calcite.

Take note of the appearance of the 350 million year old original calcite.

The preserved skeleton of the lighter colored specimen is now

composed of silica (quartz).

What is the kind of preservation for the lighter colored specimen?

Question #5. This is a plaster replica of a trilobite. Our departmental technician make specimen by: 1. taking an original trilobite fossil, 2. Making a latex (rubber) mold over the original, 3. removing the original from the mold, 4. pouring wet plaster of Paris into the mold and then pooping the replica out of the mold. Our technician made many of these replicas from the same mold.

What is the preservation type for this specimen?

Question #6. You have two valves from a modern clam in your box along with a fossil. This fossil formed by filling the hollow space of an ancient clam after it was dead and buried. After the sediment fill hardened, the shell was dissolved away, leaving this fossil.

A. Put the two shell halves together to see the hollow space formed after the soft parts decay.

B. Open the modern shells and look on the inside.

- Locate the position where the muscles were attached to the shell (two smooth spots,

one each side).

- Locate the line on the shell where the soft parts were attached (lower edge)

- Now locate the muscle scars and attachment line on the fossil.

C. What is the preservation type for this fossil specimen?

(note that this is a special case of mold/cast)

Question #7. You have two bone specimens. The larger (less dense) specimen is from an unidentified Miocene marine mammal (possible a whale). The smaller (more dense) specimen is from a Pliocene Manatee (sea cow) rib (both specimens collected in Florida).

A. Examine the "whale" bone and note the pores visible from the end.

Most of this bone is still original material. However, note that the specimen is slightly

heavier than a fresh bone (some specimens more than others). This is because some

minerals have been precipitated in the pores.

What is this process of pore filling called?

B. Why is the manatee bone so much more dense?

Question #8. This is a piece of mammoth tusk (Pleistocene Epoch, Pennsylvania). It is the original material (ivory), but it is chalky and delicate.

What might cause this specimen to be chalky and delicate?

(i.e. why is not getting harder like those in #7?)

Question #9. This is a fossil of a colonial coral (little coral lived on each box). This skeleton was originally Calcite?

A. Using your HCl acid and glass plate (on this specimen ONLY!),

determine what the composition of the fossil is now.

B. What is the preservation type for this specimen.

Question #10. This is a root from a large extinct tree from the Pennsylvanian Period (280 my).

Note that this specimen (as is common with many plant fossils), displays two types of preservation. First, all of the organic material has been distilled away, leaving only a film of Carbon.

In addition, both the general shape of the root, and the surface detail (circular attachment sites for little roots), have been preserved as an impression in the sediment.

What two types of preservation

are represented in this specimen?
 
 
 
 

PART II --- single, numbered specimens in the front & back of the room.

Question #11. "Petrified wood" Examine the two large specimens of fossil wood.

Note that these two specimens are too heavy to just have had their pores filled.

The wood tissue itself has also been changed to agate = silica = quartz.
The term "petrified" is non technical term used to describe the results of these

two processes.

What are the formal terms for these two

processes of fossil preservation .

Question #12. In this rock of limestone (Calcite), the bulk of the rock is naturally weathering away (dissolving) faster than the fossils, which are now sticking out in places. If all of these fossils were originally composed of calcite as well, why are they weathering at a different rate from the bulk rock?

Question #13. This fossil brachiopod had a skeleton originally composed of Calcite. The skeleton has been replaced by another mineral.

What mineral is the skeleton now composed of?

Question #14. This rock is a "hash" of small shell fragments. These shells would have originally been composed of Calcite, but have now been replaced by another mineral.

What mineral is the rock now composed of?
 
 

STEINKERN ROW

Many shells are made out of a Calcium Carbonate that dissolves easily.

Therefore, many groups have fossil records commonly preserved as Molds, and Steinkerns (in filling of original void space in the shell.

Question #15. Examine the Pliocene (3 my) snail shell.

Examine the Devonian snail preserved as a Steinkern.

Fill in the blanks below as to how this steinkern formed.

1. Snail died and soft parts decay.

2. Snail shell is buried and

3.

4. Steinkern exposed on the surface and collected.

Question #16.

A. These are specimens of two nicely preserved snail steinkerns (Miocene 8my)

B. These partially preserved snail steinkerns. This is the way you commonly find them.

Nothing to write on this question

Question #17. This Pliocene clam shell and steinkern are similar to your specimen #6.

Once again note the location of the muscle scars on the steinkern.

Also note that you can see the "flair" of the back end of the shell on the steinkern as well.

Nothing to write on this question

Question #18. Some animals related to squids and octopus (cephalopods) have shells.

Inside their shells they have partitions, made out of the same material as the shell.

1. CAREFULLY examine the slice through the modern chambered nautilus (in clear wrap).

2. Compare that to the slice through the small fossil nautiloid shell.

Locate the line of the original shell in fossil.

What is filling the original void space of the chambers?

What would you call the preservation type

if the shell dissolved?

3. The Large specimen is a partial steinkern of a nautiloid.

Locate where the original shell was, and note the void space.

Nothing to write on this question

----

Question #19

Bioimmuration is a fossilization process that occurs when one organism grows over the top of another organism (enhancing the preservation potential of the second).

A. The big specimen has four big barnacles growing on a colonial coral,

which itself is growing on another organism.

Carefully look to see "who" is being bioimmured.

B. Look at the bottom side of the free barnacles.

These were also growing on shells. Note however that the small organisms that were

growing on the shells before the barnacle are also preserved.

Nothing to write on this question
 
 

Question #20. Examine the cut slab of a dinosaur bone under a microscope (wet surface).

Most of the pore space is filled with silica (quartz).

What gives the silica its different colors?

(hint: read the caption on the accompanying picture)

What do you think the of the network of "yellowish brown"

material is made out of?

(hint: what was it before the pores were filled?)

Question #21. Trace fossils are the evidence of the activity of an organism. They commonly show how an organism modified the sediment. Examples are provided of feeding burrows, dwelling tubes, and track ways. You do not need to identify these, but know what a trace fossil is in general.
 
 
 
 

PSEUDOFOSSIL ROW: these are things that look like fossils but they are not actually evidence of past life (or they are commonly misidentified). These superficially look like fossils but are other natural or man made features.

#22 Some Pseudofossil Examples (name is what people incorrectly thought they were)

A. A fossil ear from Bosnia. (this is actually a shell with thick mineral deposits

resulting from a soil forming process).

B. A fossil shark tooth from North Carolina (an 1101 student brought this in).

(This is actually a trace fossil for a 3-dimensional complex burrow network

made by a shrimp.) This is a sediment fill (cast) of the burrow.

C. Nodules: The process of decay of a dead organism burred in sediment will sometimes

cause minerals to deposit, preferentially around the organism, forming a "nodule"

CAREfully look at nodules in the order given (Replace halves when finished).

nodule #1 Is a real plant fossil from the Pennsylvanian Period of Illinois.

nodule #2 Appears to be a trilobite preserved nicely in a nodule.

and ...

nodule #3 Is a trinket, manufactured and sold to tourists in Bolivia, South America.

As it turns out, so in nodule #2. Thus #2 is a pseudofossil because it is man made.

D. Fossil Turtle Skulls from South Carolina (also sold to tourists).

Orient a specimen so that you can see why people call it a turtle skull.

Actually, these are steinkerns from an Eocene clam.

Knowing what you now know about steinkerns and what you can see in the accompanying diagram of turtle skulls, what would you tell your friend who bought a "fossil turtle skull" in South Carolina (i.e., list features you might expect to see in a real turtle skull, and what you see here).