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skiman1016

Unknown Penn Dixie Find

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skiman1016

Here's another fossil from Penn Dixie I'm having trouble with. It's from the Devonian shale, and it can be hard to see in the photo as it blends in really well and is a bit worn. There is a trilobite in the upper part of the photo, I've circled the interesting feature in red. It's a circular shape with ribbed features radiating from the center. To be honest, I'm not entirely sure if it's actually a fossil or just an anomaly in the rock.  

IMG_6882.JPG

IMG_6883.JPG

IMG_6886.JPG

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ynot

Crinoid holdfast?

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Herb

I agree, a crinoid plate

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skiman1016

I would have to agree on crinoid plate as well after seeing the comparison!

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Malcolmt

I would disagree.......Looks more like a cross section of a horn coral which are super common there. In all my time I have only ever found one crinoid calyx at Penn and a plate from it would be a lot smaller than that appears to be. It is a typical size for a horn coral cross section from Penn.  

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Fossildude19

What does the other side of the plate look like? That would tell the tale. 

If it is a rugose coral, it should show up on the other side. 

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Malcolmt

Never heard of any shark material being found at Penn Dixie. Sometimes bits of  armored fish plates have bee found. Based on the looks of it and what we actually find there I would still go with the horn coral cross section near the distal end . The only calyx i have ever found at Penn was quite small and the crinoid stems that we find there are also very small in cross section. To have a plate that large would mean that the calyx on that crinoid was huge. Also to me it is not hexagonal enough to be a crinoid plate, too round like you would have in a horn coral cross section.. Also at 1 cm for a single plate, it is far beyond the size that would match up with the stems that we find there . Lets see what DevonianDigger or Fossilcrazy  has to say on this one. 

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Fossildude19
1 hour ago, Bullsnake said:

 

I'm hard pressed to doubt the opinions of  @Fossildude19, or @Malcolmt, but it looks much like a dermal denticle to me.

Factor in the age difference, as well.

 

http://www.lakeneosho.org/Paleolist/56/index.html

As Malcolm says, no shark material found in this Middle Devonian locality.

 

If we can get @skiman1016 to post a picture of the other side of the plate, we can easily settle this. 

It could very well be a rugose coral - the place is littered with them.

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piranha

 Compare with similar Devonian forms: Enterolasma, Hadrophyllum, Microcyclus, etc.

 

image.png.693ba685aef42e29cfab06c07022aed7.png

 

figures from:

 

Shimer, H.W., & Shrock, R.R. 1944

Index Fossils of North America.

Massachusetts Institute of Technology Press, 846 pp. 

 

Stumm, E.C. 1949

Three new Devonian species of Microcyclus from Michigan and Ontario.

Journal of Paleontology, 23(5)507-509

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Malcolmt

Scott, all those make a lot more sense than crinoid calyx plate or shark derma. A few moments of prep and a better picture would tell us for sure. Don't think I have ever found a microcyclus at Penn. Grabau does not mention them in Geology and Paleontology of Eighteen Mile Creek. I was thinking cross section of Hadrophyllum when I made my comment to disagree. Don't know if Enterolasma is even found at Penn 

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doushantuo

Hadrophyllids from North America(Plusquellec/GEODIVERSITAS/v.28-2,2006**free access/inFrench[monographic revision])

le9gendaasapheusacoastplai,ptykanguujjjiidp88humb.jpg

 

details of the septal architecture(to the right PALAEOCYATHUS(Enterolasma Simpson:

 

 

le9gendaasapheusacoastplai,ptykanguujjjiidp88humb.jpg

 

 

 

 

 

 

 

 

 

 

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skiman1016

Sorry for the delay in response. Unfortunately I do not have the other side to the fossil. There are some other corals in this matrix as well. A cross section of rugose does make sense, I’ve uploaded a couple more photos to try and help with the ID but it has proven difficult to photograph. 

99F34B6F-A82B-4F32-B54F-8DE00AA14AB5.jpeg

B0FC99F0-7DBE-43CA-8E2D-ED519DD94FF9.jpeg

88EE030E-AC62-4101-93CA-4B65E24BFF02.jpeg

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Fossildude19

What about the bottom of this plate?

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skiman1016
17 minutes ago, Fossildude19 said:

What about the bottom of this plate?

It’s smooth on the bottom except for a piece of trilobite:

4AC69593-8427-426D-AF39-6FCB19B1AA03.jpeg

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