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Last May, my husband and I went collecting in the Cincinnati, OH area while on vacation. I was largely focusing on collecting microfossil matrix, while he was looking for interesting macro specimens. I asked him to collect a bag of the small brachiopods that were everywhere around where we were hunting. He gathered a few dozen pieces, and when I cleaned them off, I noticed a few odd ones. :D

First, the normal examples. Cincinnetina meeki (Miller):

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And it looks like two photos at this resolution and size is the limit per post. More to come!

Edited by Mediospirifer
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The other normal example. Dalmanella emacerata (Hall):

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The C. meeki specimens I have are complete brachiopods, the D. emacerata are single valves.

More to come!

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Pathological Dalmanella emacerata (Hall). This one has two overlapping growth areas. Notice the lower margin (below the encrusting smaller brachiopod), and see the ridges on the interior surface:

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Here's a Cincinnetina meeki (Miller) with one overlap growth. Notice that the feature is visible on both valves:

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Here's another C. meeki. This one shows asymmetrical growth.

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Here's another D. emacerata. This one shows what might be the start of an overlapped growth region, but it's more subtle. Look at the right side of the exterior photo. I'm calling this (and a couple of others) sub-pathological.

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Here's another sub-pathological brachiopod, C. meeki. Look closely at the growth lines in the center of both valves--they're normally parallel or diverging, but in this one they curve towards each other.

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Thanks, Dinoboy! I thought these were pretty cool.

Here's another with similar central growth, this time D. emacerata:

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Next up: Predation marks!

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D. emacerata with a hole from gastropod predation. I've seen similar holes in bivalves a number of times, but this is the first brachiopod I've seen with this kind of mark:

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Here's another D. emacerata with a predation hole. Look above the hole in the exterior photo, and you'll see that there is another circular pit that doesn't go all the way through. There's also a suspiciously-round notch in the left side of the valve. This brachiopod appears to have been attacked by gastropods three times!

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Finally, here's a D. emacerata with odd growth rings. I'm not sure if these are pathological or not, but they turn a normally flattish valve into a sharply sloped one. Different and interesting!

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Anyone else have any pathological brachs (or know anything about them)? I'm curious as to what starts the overlapping growth pattern. Parasites or valve damage, perhaps?

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Manticocerasman

This is an interesting topic, I’ll have to check the brachiopods in my collection for pathologies and predation.

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Anyone else have any pathological brachs (or know anything about them)? I'm curious as to what starts the overlapping growth pattern. Parasites or valve damage, perhaps?

Here's a nice example that I posted a few years back. This is a Derbyia found in Kansas.

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Always love seeing the pathological brachs. So cool looking!

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Let me toss a cool one out to y'all. This is a specimen of Paraspirifer bownockeri from the Silica Shale (Givetian stage of the Devonian) of Ohio. It's "pathological" because a number of Cornulites worm tubes decided that the shell was a good location for their homes. The two coexisted for a while as you can see the shell growth around the tubes. This specimen now resides in the collection of fellow forum member Nils.

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This is a remarkable thread. Great examples. I have about a thousand species of brachs and have never seen a hole like that or worms within the shell material (lots external).

Sometimes an external scar on a brach can be from an epifauna...the brach shell preserved but the creature on it didn't.

Re the predation holes (or lack of them). The vast majority of fossil preservation is a result of some quick event...a tsunami, massive river flood, volcanic ash, ocean floor slump, etc. Organisms are buried quickly. Thus why we rarely find predation marks on Dino bones, etc. Also, once the external integrity of a shell, carcass, etc. is gone...through a boring, bite, etc....then it is more likely to rot, collapse, etc. even if there are conditions for preservation.

Now need to look more closely at my specimens! The more we learn, the more fascinating it all becomes.

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Really interesting specimens and thread!

Although "bore holes" in Ordovician brachiopods (which are rare!) are commonly referred to as evidence of gastropod predation, other explanations have been suggested and are possibly more likely. For example, these could be borings made by barnacles. See here and here for discussion of the nature of the hole-makers.

The specimen with the distortion due to Cornulites tubes is amazing!

Don

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Al Dente, Shamalama, I love your examples! I'll have to look more closely at my Devonian brachios. I know I have several encrusted ones (Cornulites, Hederella, Palaeoconchus, various bryozoa), but I haven't noticed any where the shell has grown around the hitchhiker. I may also have some 'dented' ones, they're just not as obviously pathological (rather than damaged) as the overlapped ones.

This is a remarkable thread. Great examples. I have about a thousand species of brachs and have never seen a hole like that or worms within the shell material (lots external).

Sometimes an external scar on a brach can be from an epifauna...the brach shell preserved but the creature on it didn't.

Re the predation holes (or lack of them). The vast majority of fossil preservation is a result of some quick event...a tsunami, massive river flood, volcanic ash, ocean floor slump, etc. Organisms are buried quickly. Thus why we rarely find predation marks on Dino bones, etc. Also, once the external integrity of a shell, carcass, etc. is gone...through a boring, bite, etc....then it is more likely to rot, collapse, etc. even if there are conditions for preservation.

Now need to look more closely at my specimens! The more we learn, the more fascinating it all becomes.

Predation marks are certainly more common in bivalves than any terrestrial critter, probably for exactly these reasons. A dead clam is already buried (live ones live in mud), and it's just a question of whether erosion uncovers it and washes it away or a slump buries the whole bed, live and dead together. A dead dinosaur, unless it's among a riverbed bone pile that will get buried by the next flood, will likely be scavenged or weathered away without fossilizing. And most riverbed piles are animals killed by a flood, rather than predation. You might find more crocodile predation marks than terrestrial predators! :D

I'm not sure if the shell integrity really affects the chance of fossilization in the hard shells of mollusks or brachiopods. I think protection from exposure of the shell after the animal's death is more important. I have a lot of single valve fossils!

Really interesting specimens and thread!

Although "bore holes" in Ordovician brachiopods (which are rare!) are commonly referred to as evidence of gastropod predation, other explanations have been suggested and are possibly more likely. For example, these could be borings made by barnacles. See here and here for discussion of the nature of the hole-makers.

The specimen with the distortion due to Cornulites tubes is amazing!

Don

Very interesting! I didn't know that recognized predatory gastropods hadn't yet appeared in the Ordovician (as your first link states). I've found gastros at the same sites, so i assumed they were the culprits. ;) I haven't yet read past the first couple of pages (and won't be able to read past the abstract of your second link until I can get it from my desk at work), but so far it looks intriguing!

What I can see of your second link, hypothesizing that the holes are from burrows that happen to intersect dead shells, is an interesting idea. That might explain my second holed shell better than predation--why would a predator stop halfway, or drill the edge of a shell, rather than the fleshy area? I have a number of hash plates that are basically stacks of single valves, I'll have to examine them for evidence of burrows!

Thanks!

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  • 2 weeks later...
Manticocerasman

I was inspired by this thread and went looking throug my brachiopods:

And I found some gasteropod predation on my early carboniferous brachiopods :D

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Very cool!

I find it interesting that your specimens appear to be complete brachiopods, rather than single valves. You'd think the shells would disarticulate once the occupant was eaten, unless they got buried soon after.

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I also have several Brach's that show damage, chunks missing and re growth after severe injuries. I find that so amazing that they could live and regrow from some of the wounds I have seen on them. It is really amazing. B)

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Manticocerasman

Very cool!

I find it interesting that your specimens appear to be complete brachiopods, rather than single valves. You'd think the shells would disarticulate once the occupant was eaten, unless they got buried soon after.

Hmmm I didn’t think of that. It is in fact uncommon to find disarticulated brachiopods here. (FYI: the deposits are early carboniferous )

Quick sedimentation is a possibility , but maybe only the softest parts of the brachiopod got eaten leaving the parts behind that keep the shells together.

At this location I also found 2 species of gasteropod: Bellerophon sp and Euomphalus pentangulatus.

Only small Bellerophon where found (+-1cm) , but some of the Euomphalus shells where 6cm in diameter.

Some of the bore holes are relatively large : 3.5mm in diameter so I presume that the Euomphalus could be the predator.

But this only speculation, I might find other gasteropods in the future, or bigger Bellerophons

this is a very fun exercise in Paleoecology :D

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Hmmm I didn’t think of that. It is in fact uncommon to find disarticulated brachiopods here. (FYI: the deposits are early carboniferous )

Quick sedimentation is a possibility , but maybe only the softest parts of the brachiopod got eaten leaving the parts behind that keep the shells together.

At this location I also found 2 species of gasteropod: Bellerophon sp and Euomphalus pentangulatus.

Only small Bellerophon where found (+-1cm) , but some of the Euomphalus shells where 6cm in diameter.

Some of the bore holes are relatively large : 3.5mm in diameter so I presume that the Euomphalus could be the predator.

But this only speculation, I might find other gasteropods in the future, or bigger Bellerophons

this is a very fun exercise in Paleoecology :D

Have a look at the articles FossilDAWG linked in #18. The USGS paper discusses modern predatory gastropods, and claims that the known families that follow that lifestyle don't appear in the fossil record until after the Triassic. Both articles suggest the possibility that the holes are made either by soft-bodied, currently unknown predators (USGS article), or are incidental holes from burrowing rather than predation marks (GeoScience World article). Either is an interesting hypothesis!

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Manticocerasman

Have a look at the articles FossilDAWG linked in #18. The USGS paper discusses modern predatory gastropods, and claims that the known families that follow that lifestyle don't appear in the fossil record until after the Triassic. Both articles suggest the possibility that the holes are made either by soft-bodied, currently unknown predators (USGS article), or are incidental holes from burrowing rather than predation marks (GeoScience World article). Either is an interesting hypothesis!

I mised the post of FossilDAWG that gastropods couldend have made the holes.

Interesting, soft bodied predators are a possibility.

But I don’t think accidental boring is an option, both valves would have been pierced this way.

In the specimens I collected only 1 valve was pierced.

If I go back to the quarry where I collected them, I’ll make sure to look especially after brachiopods , hopefully I can get more specimens like those to compare.

Edited by Kevin H.
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