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Horn Coral Cross Section?


Ramona

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Since this large rock is filled with Bryozoan fossils, I went off in a search to study Bryozoans.  I ended up back on this group, reading a post where Rockwood identified a photo as a Horn Coral cross section, and it looked very similar to what I have, LOL!  So, I am sticking my neck out there and asking if this might be a cross section of Horn Coral?  This is an edge of the large rock, so you are seeing two sides of it.  (first shots are looking at it from the side, third photo is looking down from the top) I have photographed it from many angles and have studied it a lot.  There seem to be some kind of sections in the center, which is what went "ding, ding, ding" in the previous post that I read on the forum regarding horn coral.  If I am wrong, at least I tried to figure it out, and I have learned quite a bit about Bryozoans in the meantime, LOL!  

 

This fossil is on a large rock that was found in Pulaski, TN, at the base of a hill/small mountain (rock weighs about 50 pounds or so).  I can share (many!) more photos if needed. I will post scaled photos in the comments.

 

Thanks!
Ramona

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It's another trepostome (probably) bryozoan again, the structure consisting of parallel, hollow zooecial tubes that are stacked together.

In a rugose coral, the structure would be radiating solid septa and various other skeletal plates, largely separated from each other by sediment or mineral growth (or sometimes voids). 

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2 hours ago, TqB said:

It's another trepostome (probably) bryozoan again, the structure consisting of parallel, hollow zooecial tubes that are stacked together.

In a rugose coral, the structure would be radiating solid septa and various other skeletal plates, largely separated from each other by sediment or mineral growth (or sometimes voids). 

OK, thanks!  I have to admit that I was wondering about the little holes along the tubes that I could see here in this image and others like it.  That explains their placement, I do believe! I will keep learning and try to not stick my neck out there so far next time!
Ramona

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6 minutes ago, Ramona said:

explains their placement

I think they were originally encrusting something that is now mostly missing.

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3 minutes ago, Rockwood said:

I think they were originally encrusting something that is now mostly missing.

I was just reading about them and was thinking of asking that question!  You beat me to it! Thanks!!  :)

Ramona

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31 minutes ago, Ramona said:

I was just reading about them and was thinking of asking that question!  You beat me to it! Thanks!!  :)

Ramona

Bonus points for what a fossil that is formed as a mold within another fossil is called.

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Steinkern AKA internal mold.

3 minutes ago, Rockwood said:

Bonus points for what a fossil that is formed as a mold within another fossil is called.

 

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9 minutes ago, DPS Ammonite said:

Steinkern AKA internal mold.

 

I thought I read a term for it in Adolf Seilacher's book Morpho Dynamics. Maybe it was just an unusual circumstance where the concept came into play.

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11 hours ago, Ramona said:

 I will keep learning and try to not stick my neck out there so far next time!
Ramona

Please keep asking, it's one of the main reasons for the forum!

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11 hours ago, Rockwood said:

Bonus points for what a fossil that is formed as a mold within another fossil is called.

Maybe a different name (though I don't see why it should be) but a fossil formed as a mould outside another fossil is a xenomorph - the most commonly reported ones are probably oysters on ammonites.

 

(Google "oyster ammonite xenomorph" otherwise you only get aliens!)

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Fascinating!! I love learning here!!  I doubt that it fits into this category but I was looking at this huge rock with a magnifying glass this morning and found some tiny little oddities that reminded me of this conversation.  Will post them and let you decide, although it looks to me like it is more like one object laying on top of another rather than moulded onto it.  

Thanks again!!

Ramona

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I doubt that this fits into the xenomorph category, but it made me think of that when I found it this morning.  I would have thought this to be a coincidence - as in the little ball just happened to land on the trepostome bryozoan, but there are at least THREE of these within close proximity of each other.  I have photos of all three, of course. I wish my measuring tape photo had been more accurate - apologies for that, but the tiny ball like structure is less than 2mm long.  It looks like a trepostome bryozoan to me, too?  Is it just a different type or is it part of the other one?

Thanks!!

Ramona

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14 minutes ago, Ramona said:

I doubt that this fits into the xenomorph category

A well founded doubt I believe. The imprint on the balls reflects the morphology of the bryozoan. If the ball shaped object left a distinctly different imprint in the bryozoan that would be a xenomorph. 

I think these are likely to be trace fossils within the bryozoan colony.

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8 minutes ago, Rockwood said:

well founded doubt I believe. The imprint on the balls reflects the morphology of the bryozoan. If the ball shaped object left a distinctly different imprint in the bryozoan that would be a xenomorph. 

I was half way out the door on the way back to work when I realized that the bryozoan imprint is in a fossil if they are indeed traces. Why wouldn't that qualify that aspect as a xenomorph ?

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2 minutes ago, Rockwood said:

I was half way out the door on the way back to work when I realized that the bryozoan imprint is in a fossil if they are indeed traces. Why wouldn't that qualify that aspect as a xenomorph ?

I will eagerly await the answer to this along with you!  Thanks for jumping in and asking questions, too!! 

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3 hours ago, Ramona said:

I will eagerly await the answer to this along with you! 

Agreed. This late on a busy day I'm just along for the ride. :)

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I can't explain the ball shape but I think it's a piece of the same bryozoan rather than a foreign body. The surface shows cross sections of the same sort of structure. Just possibly different mineralisation - for example, you get odd silicified patches in calcite fossils sometimes. Good photos by the way!

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5f91e48e9e778_Screenshot2020-10-22at20_58_44.png.9608e4e120f21f4725d0c1f6c64c905d.png

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32 minutes ago, TqB said:

I can't explain the ball shape

I think the change in preservation could possibly be the result of the different mineral composition of the burrow fossil at the center of the ball.

There's a xenomorph in there. It just needs a good CT scan set on fry to bring it to light.

Maybe.  :headscratch::Confused05:

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33 minutes ago, Rockwood said:

I think the change in preservation could possibly be the result of the different mineral composition of the burrow fossil at the center of the ball.

There's a xenomorph in there. It just needs a good CT scan set on fry to bring it to light.

Maybe.  :headscratch::Confused05:

 

1 hour ago, TqB said:

I can't explain the ball shape but I think it's a piece of the same bryozoan rather than a foreign body. The surface shows cross sections of the same sort of structure. Just possibly different mineralisation - for example, you get odd silicified patches in calcite fossils sometimes. Good photos by the way!

5f91b0bde911e_Screenshot2020-10-22at17_16_43.png.25cff2692b69b91a631702a4cf7bb011.png

5f91e48e9e778_Screenshot2020-10-22at20_58_44.png.9608e4e120f21f4725d0c1f6c64c905d.png

OK, I am game!  Thanks for the compliment on my photos, by the way!  Macro photography fascinates me - and I am a photographer by trade - so THAT part of this challenge I am up to!   And, now you introduced a new THING that I want to try to find!  Rockwood, I can't do CT frying, but I can do some fun things with the images, LOL!  This is a different little ball - see if you can see enough differences in it - and in the "negative image" to figure out some more answers? 

 

 

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3 hours ago, Ramona said:

Rockwood, I can't do CT frying, but I can do some fun things with the images

Indeed. You've convinced me that weathering is at the core of this issue.

The core appears to be less weathered, leaving the zooecia filled in the center and vacant near the surface. As @TqB suggested, there may have been a slight variation in its preservation to begin with. 

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