Eggshell Decomposition

[GeneralAnesthetic]

[GeneralAnesthetic]

[Auspex]

39 minutes ago, GeneralAnesthetic said:

when you start rinsing water over the same soluble substances, they generally mix and become one

???

Calcium is potentially water soluble, if the water has a low pH. Silica, not so much.

[Auspex]

13 minutes ago, GeneralAnesthetic said:

All of these came from the same large limestone boulder. 

These are concretions. 2nd from left, top row, is a geode.
None of these shown have an organic origin.

[Pagurus]

3 hours ago, GeneralAnesthetic said:

YES YES YES!!!!! This is exactly what I needed. As with any science, terminology is what I am missing. Meteoric diagenesis is part of what has to be figured out here. Because according to Idaho state history, there have been a few large impacts along the 300mi in question. The interesting thing to be in this topic of permineralization is that the biggest opal mine in Idaho is in the blast radius of where the largest impact occured. Which poses my question of whether or not these opals are in fact water related, which is also likely considering the ice jam that would have been there ~3mya. 

 

Yes, the terminology can certainly be confusing. I think you are confusing the geologic use of "meteoric" with the astronomical use. Try googling "meteoric water."

 

[CBchiefski]

11 hours ago, GeneralAnesthetic said:

According to Google, all knowing and all wise.....

 

"Eggshell is made almost entirely of calcium carbonate (CaCO₃) crystals. It is a semipermeable membrane, which means that air and moisture can pass through its pores. The shell also has a thin outermost coating called the bloom or cuticle that helps keep out bacteria and dust."

 

"Limestone is a sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO3). It often has variable amounts of silica in it, as well as varying amounts of clay, silt, and sand. Limestone rocks fall under the category of sedimentary rocks that are made from mineral calcite."

 

The question I pose is this, well there are several..........

 

If amphibian/reptile or bird species prefer to lay their eggs near water sources wouldn't it be a likely assumption that the permineralization of the eggshell would be reclaimed by the surrounding silicates while the inside turns to agate? Meanwhile, larger dinos layed their eggs in more forested inland areas and were not exposed to the same permineralization since there was less water exchange.? 

 

In the permineralization or petrification process, if an egg is in an undeveloped state would it agatize mostly transparent/opaque? What are, if any, the artifacts or features you guys look for beyond the obvious cracked shell on the exterior? 

 

I have looked but I have yet to find a good read that explains well what happens to eggs, soft tissue, and entire animals that are enveloped in volcanic mud flows. I just know there is a good read out there somewhere that gives a reasonable explanation to what happens to an animals remains as they fossilize. Maybe there isn't, I have yet to find the name of the guy that sat and watched it all happen. Does the blood cause the fe203 stain in a fossil? Do heavier minerals like Iron have a sedimentation characteristic during permineralization? Does displaced water content of the animal cause air pockets to form during permineralization? In nature, what causes living sources of silica to be in either crystalline or non-crystalline form?

 

Am going to not be too technical and keep this in simple terms. Given the amount of eggshell found in some formations (Zhutian and Dafeng) compared to almost no eggshell in others (Hell Creek), there could be a chemical reaction in some locations which destroys eggshell prior to fossilization. I use Zhutian, Dafeng, and Hell Creek as formation examples since they are similar in age. There are also many other processes, such a basic erosion that could be reducing the amount of eggshell which makes it into the fossil record. It is likely some eggshell did dissolve away and so did not make it into the fossil record, however, substantiating such a statement is difficult. I can tell you more than a few dinosaur nests are found in calcareous mudstone with large calcite veins, and such a lithology (rock composition) could easily be dissolved under circumstances which would also dissolve eggshell. The fact that both the rock layers and eggs are present clearly shows there were favorable conditions for both to preserve.

Near water and in contact with water are vastly two different conditions, most of the limestone you are referring to is in direct contact with water for a portion of time and even then, in certain conditions limestone preserves very well. At the moment there is not really enough evidence to say with any confidence where "larger dinos layed their eggs" even in the massive sauropod nesting grounds of Argentina there is some debate over just what environmental setting those nest were in. There simply have not been enough nesting sites found yet to say where they preferred to lay eggs. The best attempts have used bird nest locations as a modern analog, however, there are issues with doing a study this way.

For the volcanic flows, there is a natural cast of a mammal which was enveloped by a flow, however, this is nothing more than a cast. I do not know of any eggs being found in association with a flow. There is a dinosaur nest I am currently working on which was buried in a volcanic ash layer however that is the closest I have seen.

11 hours ago, Auspex said:

I think you are getting way ahead of possibilities with your logic tree. Build on the trunk fundamentals before going so far out on one limb:

"Is eggshell reclaimed by the surrounding silicates?"

"Could an egg's inside turn to agate?"
Do you catch my drift? Half-informed speculation makes a rickety and treacherous scaffolding on which to build a theory.

Agreed!

10 hours ago, HamptonsDoc said:

I can’t answer most of these questions but I will say that agatized eggs do exist. The ones I’ve seen are from Argentina. The shell structure and egg shape is most similar to identified Sauropod eggs from the region and the agate is blue and opaque. 

 

8 hours ago, Auspex said:

I assume this is a case of agate slowly filling the void within the shell, and not "agatization" of the watery, organic contents (which are unlikely to persist long enough for that to occur)? I know of no mechanism by which soft tissues could 'turn to agate'.

This is also a good example of eggshell not dissolving, but instead becoming further mineralized. I suspect that survival of the shell has more to do with the pH of the depositional environment (with acidic being more antagonistic than alkaline) than a wet-vs-dry environment (other than the necessity of rapid burial for preservation at all).

Yes, the agate is present but taphonomically does not appear to be at all related to the internals of an egg, that said there could have been a chemical reaction which occurred between the substrate (soils) and the eggshell. To my knowledge, all the agate eggs have nothing associated with them such as embryonic remains that could have affected chemistry, though even if present that would be very unlikely.

7 hours ago, GeneralAnesthetic said:

 

Best way ever to say, "no question is a stupid question." I suppose I could say the same for the half-informed idea of what level of speculative thought has gone into this. I never said I was right, I just posed the questions. As with anything I study, if a question remains unanswered then I have reason to continue my bent. You will find that I have a problem asking questions sometimes, it comes with the autism spectrum. So perhaps it is you that should weave a tapestry of caution when being so indirectly insulting. 

 

"Permineralization takes place when ground water carrying dissolved minerals infiltrates the microscopic pores and cavities in bone, wood or shell. The minerals being deposited produce stony fossils that still contain a good deal of their original solid material. Bones, teeth and many marine organisms are preserved in this way. The fossil wood from the Petrified Forest of Arizona are a famous example of this type of preservation. The fossil teeth and bones of the Oligocene badlands of South Dakota and Nebraska are also common example of this type of fossilization, as well as the extensive deposits of Jurassic dinosaur bones in Utah and Colorado."  Cited: http://www.fossilmuseum.net/fossilrecord/fossilization/fossilization.htm 

 

So, I am building "treacherous scaffolding" then explain how this doesn't happen? Surrounding the "alleged" fossil is silica rich substrate. This substrate is not only contributing it's own mineral content e.g. silica, but also exchanging mineral. If CaCO3 is the main mineral in both the limestone and the shells of lesser vertebrates, then how in the world does a person contend that the shell would not be "reclaimed" as my noob terminology put it. As I put it, my theory would state. The calcium carbonate shell would slowly become part of the surrounding substrate, so when it breaks free it appears to be nothing more than a unique piece of quartz. However, pot marks and striations do not match with river washed stones. Which leads me back to my original question that was apparently so wrong. I love to be corrected, I want my theories to be supported, but I am ok with being wrong. 

The calcite is not so much reclaimed, but rather, if it dissolves then it is replaced by other minerals, this process is known as replacement or recrystallization.  Some fossilized dinosaur eggs I am working on currently have aragonite and micrite now making up parts the eggshell for example.

Edited July 8, 2018 by CBchiefski
Typo

[HamptonsDoc]

1 hour ago, CBchiefski said:

Yes, the agate is present but taphonomically does not appear to be at all related to the internals of an egg, that said there could have been a chemical reaction which occurred between the substrate (soils) and the eggshell. To my knowledge, all the agate eggs have nothing associated with them such as embryonic remains that could have affected chemistry, though even if present that would be very unlikely.

Agreed. I don’t know of any embryonic remains identified with an agatized egg either. Just meant that the eggs are similar to what is typically referred to as Saltasaurus eggs from other parts of Argentina. 

[snolly50]

13 hours ago, GeneralAnesthetic said:

I have looked but I have yet to find a good read that explains well what happens to eggs, soft tissue, and entire animals that are enveloped in volcanic mud flows.

Pompeii.

The victims, human and animal, were buried in ash and mud. The flesh rotted away, leaving bone and detailed voids in the shape of the entombed. 

 

[doushantuo]

Eggs from an area known to have had high heat flow: 

 

 

[doushantuo]

This elegant figure is from a Graf/Tabor et al(Gobi Desert egg diagenesis) preprint:

 

[doushantuo]

geodmin

(about 5 Mb)

This being(see below):

 

[doushantuo]

For the record: Kohring knew his eggs.He died too soon

Below: from Buffetaut et al/2005

 

[GeneralAnesthetic]

The feedback has been most excellent. I had to go through a whole bunch of learning to get the necessary images, the conditions are consistent with chemical processes and extreme heat. Pressures are a question being looked at now. New, less convoluted post coming soon.