[John Christian]

Hello,

Here’s an easy solution. Type your password into the username field. If it looks ok then cut it. Enter username then past password into password field. Easy.

[John Christian]

Thanks again Jack. @jkallmeyer

Since body fossils include molds and casts, using body fossil would not work in the definitions because according to 2 “: Molds can only be made against molds. (Not true.) What is the definition of: “A mold is an imprint of _______________? I could make up and define a new term of art such as “alpha fossil” to put in the “_____________”. For example: “an alpha fossil” is defined as an organism, fossil, fossil to be or a cast thereof. I guess that I am looking for the paleontology equivalent of Black’s Law Dictionary to find definitions of mold and cast.

Are there any rules when applying the terms mold and cast to trace fossils such as the infilling of a (shrimp) burrow or the infilling of a footprint? The infilling of a burrow is a ____________? I suggest that “infilling of a burrow is a mold of the interior of the burrow.” Also some people claim that: the infilling of a burrow is a cast because the borrow is a mold of the organism that created the burrow. The last sentence makes no logical sense because a “cast is a replica and/or reasonable copy of” an organism. A burrow infilling looks nothing like a shrimp.

In other words, if there are no coherent definitions for mold and cast referring to trace fossils, I would like to create a set and publish them. My definitions/rules 7 and 8 could be a basis for the new definitions.

Thanks again.

[John Christian]

Thank you Jack (and everyone else.) @jkallmeyer

You provided me a very helpful analysis that found the same two weaknesses that I was most concerned about.

If I substitute “body fossil” for “original fossil” will all the other definitions and rules make sense and create no major contradictions? I hope that a “body fossil” includes a cast because a mold can be made against a cast (second generation mold.)

I created rules 7 and 8 because I have noticed that many professional paleontologists consider that casts and molds can be made from well executed trace fossils such as dinosaur footprints. I assume that one could reason that a footprint infilling is a cast because a “caste is a replica and/or reasonable copy of a body fossil” (the foot.) Do you think the infilling of a well executed and preserved footprint can ever be considered a cast? Should I take out 7 and 8 and include a note that some paleontologists think that casts and molds can be made from certain trace fossils such as footprints?

Thanks again for your help Jack and anyone else.

John

[John Christian]

@rleder, @bdattilo, @bmacfadden, @crobins, @rebecca-freeman, @jkallmeyer

Thanks for everyone’s help.

Using suggestions provided by you and information from other sources, I am creating a set of definitions and rules to help everyone determine if a fossil is a mold or a cast. I am interested in making the definitions and rules better, clearer and easier to use. I need the help of everyone.

Here is what I have:

1. A mold is an imprint of an original fossil.
2. Molds can only be made against an original fossil.
3. A cast is a replica and/or reasonable copy of an original fossil.
4. A cast can only be made against a mold of an original fossil.
5. An original fossil is defined as an organism, fossil, fossil to be or a cast thereof.
6. Trace fossils are various tracks, trails and burrows that give us information about what the original organism did while alive.
7. The surface of a trace fossil created by the original organism against a material is an original fossil when the surface of a trace fossil created by the original organism against a material cannot create a cast of the original organism that created the trace fossil.
8. The surface of a trace fossil created by the original organism against a material is a mold when the surface of a trace fossil created by the original organism against a material can create a cast of the original organism that created the trace fossil.

Here are some related rules or corollaries:

9. An original fossil must exist before the mold of the original fossil.
10. The mold of an original fossil must exist before the cast of the original fossil.
11. A cast of the original fossil cannot be created against the original fossil.

Let’s apply the definitions and rules to an actual situation. Is a filling contained within the original shells of a closed bivalve a mold or a cast? A mold (the infilling) is an imprint of the original fossil (the closed bivalve.) The mold (infilling) can only be made against the original fossil (closed bivalve.) Remember, a cast (replica and/or reasonable copy of an original fossil) can only be made against a mold. The infilling can create a cast (the interior only) of the original closed bivalve. The infilling is not a cast because the infilling is not a replica and/or reasonable copy of an original fossil.

It is important that we agree what the original fossil is first. Then we can determine what are the fossil mold(s) and cast(s). We must also remember that a cast of the original fossil must be a reasonable copy of the original fossil.

I welcome any suggestions, new definitions and rules along with supporting rational arguments and reasoning. Sources for definitions would be helpful.

I am also willing use these definitions and rules to see if a fossil that you describe is a mold, cast or other type of fossil. The more we use these rules and definitions, the better they become.

Once we improve these definitions and rules please use them.

Thanks,

John

[John Christian]

Thanks Benjamin,

So to simplify, a cast is made only against a mold. Right? A mold is only made by direct contact with the original fossil. Correct?  Therefor my steinkern is an internal mold since it formed against the original shell… right?

I am a little confused by your use of “positive” and “negative” in reference to impressions. Does “positive” and “negative”  refer to concave and convex? If “negative = cast” then the definition of a “mold” would be a: mold impression of the original formed by contact with the original. That is a confusing definition.

If “negative” = mold = convex, then some molds break that rule. A steinkern which can be an interior mold is convex in most bivalves. Exterior molds are usually concave but are partly convex when the original bivalve has a concave valve (some pectens and brachiopods.)

Thanks for you help.

@bdattilo

 

 

[John Christian]

@jkallmeyer

Jack,

Here’s an article which mentions the use of a 75% solution. There are also references to other articles that mention the use of Rewoquat.      http://palaeo-electronica.org/content/2013/530-microfossil-extraction

[John Christian]

You can also order photo scales with the geological time divisions on the back from the Geological Society of America.

https://rock.geosociety.org/Store/detail.aspx?id=PTS001

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