Anyone recognize this?

[Paciphacops]

Any recognize this? I have come across a few of these recently in the Lebanon limestone in middle TN, mid/late ordovician. Most have been much smaller. This one still has a thin layer of matrix over much of the surface (with a fragment of a graptolite), but it's the only one I have a photo of. 

 

Thanks

[KimTexan]

May we have photos from other angles?

I’m taking a wild guess when I say brachiopod maybe Atrypida.

I assume you mean the whole round part and not just the part that comes to an apex. I can’t zoom in and get a clear pic.

 

I think your camera may have focused on the leather texture rather than the specimen.  When I zoom in it is fuzzy, but the leather is sharp as can be.

 

[Paciphacops]

Here are a few additional photos with better lighting. The whole round /oval thing is the fossil, with a prominent, weathered,  raised ridge across it. Sorry about the matrix. I prepped away some, but wanted to see if I can ID it before spending a lot of time on it.

[Paciphacops]

[DevonianDigger]

Looks like a trilobite pygidium to me. Trying to work out which one.

[DevonianDigger]

I take that back. The angle in the second picture in the second post was deceptive. I have no idea, sorry :/

[Paciphacops]

24 minutes ago, DevonianDigger said:

Looks like a trilobite pygidium to me. Trying to work out which one.

 

When I first saw this, I thought Isotelus pygidium, but then saw the ridge. I'm thinking some sort of bivalve, but I have not matched it to any of the better known Lebanon fossils, or anything else from similar strata in Ohio or Oklahoma.  

[Paciphacops]

One more photo showing a close up of the surface texture.

[ynot]

1 hour ago, Paciphacops said:

One more photo showing a close up of the surface texture.

This looks like a bunch of small calcite crystals. These would form in a cavity within the rock, probably between two shell pieces.

This makes it very hard to say what the piece is other than shell fragment, possibly bivalve.

[Paciphacops]

12 hours ago, ynot said:

These would form in a cavity within the rock, probably between two shell pieces.

 

This is clearly not a cast, but very well preserved shell-like material. You can see the cross section of the shell on the weathered ridge. The small calcite crystal texture looks very similar to Isotelus material from the same road cut, under the microscope. I would think that there would be radiating striations if it was a bivalve, but I don't see anything like that.

 

It is obvious that I need to do more prep work, so the margins are visible. 

[FossilDAWG]

I'm fairly confident it is a gastropod, along the lines of Pterotheca or maybe Bucanopsis.

 

Don

[Paciphacops]

12 minutes ago, FossilDAWG said:

I'm fairly confident it is a gastropod, along the lines of Pterotheca or maybe Bucanopsis.

 

Pterotheca looks like a possible match.

 

Thanks Don!

[piranha]

Pterotheca saffordi 

 

description & figures:

 

Wahlman, G.P. 1992

Middle and Upper Ordovician symmetrical univalved mollusks (Monoplacophora and Bellerophontina) of the Cincinnati Arch region.

United States Geological Survey Professional Paper, 1066-O:1-213   PDF LINK

 

original description:

 

Hall, J. 1861

Upon some new and other species of fossils, from the rocks of the Hudson-river group of Ohio and the western states; with descriptions.

Annual report of the Regents of the University of the State of New York on the State Cabinet of Natural History, 14:89-109