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JUAN EMMANUEL

Hi guys so I have this Hebertella occidentalis specimen I collected yesterday from the Credit River at Streetsville, Mississauga, Ontario, which belongs to the Upper Member of the Georgian Bay Formation.

Do these look like predation marks? There are also what appears to some crystallized grains inside these marks and I think they could be some sort of calcite. Sorry for the noisy grain of the image, but I hope this will help. 

7B45BCB5-EE35-45AE-BABD-CD8D12786E4B.thumb.jpeg.bd0e5c0f6a23b4a4bf3471b623f076ba.jpeg

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ynot

I do not see predation here.

Looks like natural breakage showing geodized interior.

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Mediospirifer

I see a few spots on that shell that could be worm borings:

 

5ce61b2286f58_hebertellapredationmarks.jpg.5812768f9aff5db8c87d6f629e4c002c.jpg

It's hard to tell from the photo whether 1 and 2 are boreholes or blobs of matrix stuck to the shell. The marks at 3 look like borings, but they look like marks I've seen that I attribute to burrowing in a dead shell. If 1 and 2 are holes, they could also be from postmortem burrowing rather than predation.

 

I have a few Ordovician bored brachiopods that I wanted to know more about. Apparantly, the modern gastropod families that are known to prey on other mollusks by boring shells don't appear in the fossil record until well after the Ordovician (although I don't remember offhand what era they do appear in). There are certainly examples of hardground burrowings from that era that pierce multiple shells.

 

The edge damage in your red circle looks like natural breakage.

 

Interesting specimen!

 

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Tidgy's Dad

I think it's marks left by epibionts that were fused to the shell and either broke off or slightly bored into it. The edge piece, weakened by the borings has broken off. 

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doushantuo

Agree with Medio &Tidgy there

BTW:

brachpredatbullmarsci29320653_s12.pdf

Michal Kowalewski* and Karl W. Flessa

BULLETIN OF MARINE SCIENCE, 66(2): 405–416, 2000

*author of some high-end(quantitative) brachiopod taphonomy literature

 a documented case/paywalled:

Cephalopod Predation on a Desmoinesian Brachiopod from the Naco Formation, Central Arizona
David K. Elliott and Douglas C. Brew
Journal of Paleontology
Vol. 62, No. 1 (Jan., 1988), pp. 145-147

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Herb

looks like some borings, maybe worms or sponges

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