Pennsylvanian Nautiloids and Brachiopods

[Lucid_Bot]

Hello, found  what I think are nautiloids and brachiopods. I found the rock in a stream and I can't say what limestone (maybe brush creek or pine creek), but the area is Glenshaw Formation in northern Allegheny County, Pennsylvania. It's quite difficult for me to get good pictures, let alone good pictures with scale, so I'll tell you that the first two pictures are 2 cm (same organism), the second is 5.5 cm and the largest Nautilus in the last pictures is about 6 cm. All information is appreciated, thanks!

[ClearLake]

I am going to say that the first brachiopod is a Derbyia and the second is a Linoproductus based on wrinkling that I think I am seeing near the posterior edges.  ID's on both are made a bit more difficult by the not preserved or not visible hinge line.  Lets see what @cngodles or @Tidgy's Dad have to say as they both are probably more familiar with these than I am.  

[Misha]

I think the first is not Derbiya sp. but the brachial valve to a productid.

The nautiloid is Metacoceras I think.

[ClearLake]

4 minutes ago, Misha said:

I think the first is not Derbiya sp. but the brachial valve to a productid

That could be as I just noticed the wrinkling on that one in the lower right of the second picture after you had me take a second look.  I thought the first picture looked too elevated for a productid brachial, but maybe not.  

[cngodles]

That is Metacoceras for sure. The genus is a bit of a garbage taxon with several species named. It’s easily one of the two most common cephalopods in this formation, with only Pseudorthoceras able to challenge it.

 

You are looking at mostly a steinkern; the black lines are the inside attachments of the camerae to the shell walls. They don’t retain that thickness throughout. They can be quite interesting individually in steinkern form.

 

Edited November 2, 2022 by cngodles

[Thomas.Dodson]

5 hours ago, Misha said:

I think the first is not Derbiya sp. but the brachial valve to a productid.

I agree. It seems similar to some Leptaena sp.

 

I agree with Metacoceras and Linoproductus for the others.

[DPS Ammonite]

10 minutes ago, Thomas.Dodson said:

It seems similar to some Leptaena sp.

Probably not Leptaena since it died out in the Early Mississippian; formation claimed to be Pennsylvanian by OP.

[DPS Ammonite]

A slight side note; that is a weird pattern on the purported Linoproductus. I wonder if the brachiopod was injured and then healed, disturbing the normally radial ribs of the brachiopod.

 

@Tidgy's Dad

 

Edited November 2, 2022 by DPS Ammonite

[hemipristis]

I have not seen nautiloids from Pennsylvania.  Very nice!

[Lucid_Bot]

Thanks to everyone who has posted. Just wondering, nearly all of the fossils I find in limestone are incomplete or poorly preserved; is this typical of the limestone around here, am I just getting lucky, am I doing something wrong? This rock is very hard and brittle and resists clean splits.

[Lucid_Bot]

6 hours ago, DPS Ammonite said:

Probably not Leptaena since it died out in the Early Mississippian; formation claimed to be Pennsylvanian by OP.

Yes, Mississippian rocks are far from my location. Almost certainly Pennsylvanian.

[hemipristis]

22 minutes ago, Lucid_Bot said:

Thanks to everyone who has posted. Just wondering, nearly all of the fossils I find in limestone are incomplete or poorly preserved; is this typical of the limestone around here, am I just getting lucky, am I doing something wrong? This rock is very hard and brittle and resists clean splits.

I believe location may have something to do with it.  Consider the ages of the limestones in the Appalachians, and the tectonic history:  they felt the effects of both Europe and Africa mashing into them, and responded in kind with the folds and faults that you see in the field.  

 

I'm not the expert in fossil hunting in the Appalachians by any stretch, but in my fossilizing jaunts in the Appalachians it seems that fossil preservation is better to the north in New York, and to the south in Tennessee than in the mid-Atlantic states. I'd be curious to hear the input from folks that collect in that region regularly

[cngodles]

7 hours ago, Lucid_Bot said:

Just wondering, nearly all of the fossils I find in limestone are incomplete or poorly preserved;

 

https://fossil.15656.com/2021/05/04/the-3-preservation-types-of-glenshaw-formation-fossil-marine-fauna/

[Tidgy's Dad]

Nothing to add, really. 

Great nautiloid. 

[Tidgy's Dad]

On 11/2/2022 at 5:59 AM, DPS Ammonite said:

A slight side note; that is a weird pattern on the purported Linoproductus. I wonder if the brachiopod was injured and then healed, disturbing the normally radial ribs of the brachiopod.

 

@Tidgy's Dad

 

Yes, I think that is very likely the case. 

Quite common on later Palaeozoic specimens especially. 

Edited November 7, 2022 by Tidgy's Dad