Eggshell Decomposition

[GeneralAnesthetic]

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? 

 

I have lot's more questions I'll do my best to google, but dang it's hard to find some of these answers. "Someone, out there on the net shouted. "Take a snarge class!"

 

 

 

 

[Auspex]

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.

[HamptonsDoc]

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. 

[Auspex]

1 hour 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. 

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).

[Kane]

3 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.

 

 

 

 

It very much depends. In some instances, quick burial by mud will not guarantee soft tissue preservation. For example, the trilobites at Penn Dixie were certainly buried quickly in mud, but you will not encounter any soft tissue preservation. In other cases where there is some degree of anoxic conditions + quick burial, you get Lagerstatte areas that will preserve soft tissue. Perhaps some reading on Lagerstatte would answer some of your questions here.

[GeneralAnesthetic]

 

3 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.

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. 

[GeneralAnesthetic]

I appreciate the responses so far. Watch me do it wrong, better than you've seen it done before!

Edited July 7, 2018 by GeneralAnesthetic
correction

[GeneralAnesthetic]

Chunk of limestone my questions are mostly based on. The brighter green foreign object is likely a light blue thunder egg. While others I've found appear to be remnants of shells on one side of the object. 

[JohnJ]

You'll need much sharper images with close-ups to give us an idea of what you've found. 

[doushantuo]

repost:

[GeneralAnesthetic]

2 minutes ago, JohnJ said:

You'll need much sharper images with close-ups to give us an idea of what you've found. 

For that I would really like to provide a series of on-site photos where I break apart the limestone in real-time. 

[Kane]

Just now, GeneralAnesthetic said:

For that I would really like to provide a series of on-site photos where I break apart the limestone in real-time. 

Clearly focused images of the rocks should suffice in making a determination. 

[GeneralAnesthetic]

3 minutes ago, doushantuo said:

repost:

Thank you for that! Do you have a link to the entire read/thread? 

 

[doushantuo]

Sorry,I posted this in one of the numerous threads on purported or real vertebrate eggs.

I pointed out its usefulness ,but I think it went unnoticed

As you can plainly see, I post quite a lot,and it's kinda hard to look up

you might want to (try to) read this one(outtake below)

[JohnJ]

3 minutes ago, GeneralAnesthetic said:

For that I would really like to provide a series of on-site photos where I break apart the limestone in real-time. 

Take close-up images of the specimens you have.

[GeneralAnesthetic]

1 minute ago, Kane said:

Clearly focused images of the rocks should suffice in making a determination. 

Sure, I understand. It'll take me about a day to complete. When I can get into it. I gotta leave for Seattle today though. I need to take photos from both sides of the river to show the complete picture. I am still looking for the main source of the green limestone. The boulders, which are nearly car sized in places, do not seem to be from that immediate area. The riverbed shows sporadic deposits of large glacial stones, you can see spots where ice built up on islands and eventually melted, leaving piles of stones. So really, this "Picture" is 300 miles long, and will take some time to assemble. 

[GeneralAnesthetic]

4 minutes ago, JohnJ said:

Take close-up images of the specimens you have.

I'll take some before I leave today.

 

[Auspex]

5 hours ago, GeneralAnesthetic said:

the permineralization of the eggshell would be reclaimed by the surrounding silicates

This doesn't make any sense. By "reclaimed", do you mean that the permineraliszation is somehow absorbed by the surrounding silicates?

Do I misunderstand your meaning? Seems like a misunderstanding of the taphonomic process to me to me...

 

[GeneralAnesthetic]

6 minutes ago, doushantuo said:

Sorry,I posted this in one of the numerous threads on purported or real vertebrate eggs.

I pointed out its usefulness ,but I think it went unnoticed

As you can plainly see, I post quite a lot,and it's kinda hard to look up

you might want to (try to) read this one(outtake below)

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. 

[Kane]

4 minutes ago, GeneralAnesthetic said:

Sure, I understand. It'll take me about a day to complete. When I can get into it. I gotta leave for Seattle today though. I need to take photos from both sides of the river to show the complete picture. I am still looking for the main source of the green limestone. The boulders, which are nearly car sized in places, do not seem to be from that immediate area. The riverbed shows sporadic deposits of large glacial stones, you can see spots where ice built up on islands and eventually melted, leaving piles of stones. So really, this "Picture" is 300 miles long, and will take some time to assemble. 

You might be overthinking this. A few samples would likely be enough to test for what these rocks are. A large field survey may not be necessary.

[GeneralAnesthetic]

5 minutes ago, Auspex said:

This doesn't make any sense. By "reclaimed", do you mean that the permineraliszation is somehow absorbed by the surrounding silicates?

Do I misunderstand your meaning? Seems like a misunderstanding of the taphonomic process to me to me...

 

I don't know what to call it, other than when you start rinsing water over the same soluble substances, they generally mix and become one. 

[Kane]

I would call that erosion.

[GeneralAnesthetic]

2 minutes ago, Kane said:

You might be overthinking this. A few samples would likely be enough to test for what these rocks are. A large field survey may not be necessary.

I can dig that, I overthink literally everything, then I overthink it again. I've reinvented the wheel several times, but it still comes out mostly rounded. As for the large field survey, I am only interested in the entirety of it because of the overwhelming evidence that the site this all comes from is like a drain. It has collected here for God knows how long. Through volcanic and meteoric events, the pressures and heat involved with the thermally driven mud flows tell me it is far more valuable to understand it all. But I digress, lemme get to some photo taking. 

[doushantuo]

It is yet unclear how long the membrana testacea remains intact,and if that might retard microbial degradation.

 

[GeneralAnesthetic]

All of these came from the same large limestone boulder.