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A Trilobite Inside Something Else

a cephalopod or brachiopod

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#1 fengw03

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Posted 08 November 2011 - 03:10 PM

This fossil comes from the Mulde layers, Silutian, near Djupvik, Gotland, Sweden.The trilobite fragments belong to Calymene tuberculata. However, the interesting thing about it is that the trilobite seems to be entombed in a shell of something else.

At first glance, I though it was a cephalopod because of its long tube like shape, which also makes sense because ceplhalopods feed on trilobites. But from the sideview, I can see that the shell is made of two halves, and there is no visible segments along the tube. And you can see curves from one side, which makes it look like a brachiopod. Does brachiopod eat trilobite? Or could it be a crushed cephalopod?

Does anybody have any idea about what it is? Sorry that I don't have tools to further prepare the fossil, so the shell is still largely covered by the matrix.

The pictures below are showing topview, sideview and backview (trilobite is on the right).

Attached Thumbnails

  • 01.jpg
  • 02.jpg
  • 03.jpg


#2 fengw03

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Posted 08 November 2011 - 03:11 PM

Some more pictures.

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  • 04.jpg
  • 05.jpg
  • 07.jpg


#3 fengw03

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Posted 08 November 2011 - 03:14 PM

I found this paper talking about trilobites found inside cephalopods. It seems not uncommon to find entombment of trilobites in cephalopods.

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#4 Fossildude19

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Posted 08 November 2011 - 03:29 PM

There was a post not too long ago with a PDF attached, about a brachiopod that had a phacopid trilobite entombed in it.
CLICK LINK
(Thanks Scott!)
I think it was postulated that the trilobite crawled in an open shell, seeking cover, and got buried inside of it.
It may have been something like this.
Regards,

Tim
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#5 fengw03

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Posted 08 November 2011 - 03:43 PM

Thanks for the useful information, Tim. Empty shells seem to be a good place for shedding trilobites to hide. But do you have any idea whether this is a cephalopod or brachiopod? I really can't tell.

Wei

There was a post not too long ago with a PDF attached, about a brachiopod that had a phacopid trilobite entombed in it.
CLICK LINK
(Thanks Scott!)
I think it was postulated that the trilobite crawled in an open shell, seeking cover, and got buried inside of it.
It may have been something like this.
Regards,



#6 Fossildude19

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Posted 08 November 2011 - 04:01 PM

Wei,
If I had to guess, I would say that it looks more like a bryozoan or coral, from the texture I can see on the outside of it in Pic # 3 of your first post.
If I can only choose cephalopod or brachiopod, I would lean towards brachiopod.
I think more prep via air abrasion would needed to be done to determine exactly what it is, however.
Regards,

Tim
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John Muir  
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#7 fengw03

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Posted 08 November 2011 - 04:07 PM

Tim, I do see some kind of bryozoans attached to the shell, but not sure that the whole piece is a bryozoan. Thanks for the guess. Maybe it's time for me to start my own fossil prep. :)

Wei,
If I had to guess, I would say that it looks more like a bryozoan or coral, from the texture I can see on the outside of it in Pic # 3 of your first post.
If I can only choose cephalopod or brachiopod, I would lean towards brachiopod.
I think more prep via air abrasion would needed to be done to determine exactly what it is, however.
Regards,





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