Pennsylvanian Nautiloid Collectors

[howard_l]

I was doing some research on some coiled nautiloids I have found in the lower Borden (Mississippian), I am fairly certain they are Epidomatoceras. They are a lot smaller than other nautiloids I find in the area but I have found enough of the same size to conclude they are not juveniles. I am also finding much larger nautiloids higher up in the Borden that look very similar. I had found some descriptions of some Pennsylvanian age Domatoceras that sounded a lot like the larger nautiloids that I have identified by an older name of Thrincoceras. Can anyone who has specimens of Domatoceras (especially large more mature specimens) please post them on this thread so that I can compare them to the larger ones from KY. Thank You

[Missourian]

Here's a picture of one that I had handy from an old post:

Westerville Limestone, Missourian, Pennsylvanian

Raytown, Missouri

[howard_l]

Very nice! The basic form is there but the main area I need to see is the Ventral back, basically the back end of the coil. I wanted to see if mature specimens have a grove up the back. The big specimens I find have a deep grove going up the back.

[Missourian]

The back is somewhat 'squared off' like Metacoceras, but lacks the 'knobs' on the edges. I think the back may even be slightly concave, but I can't remember at the moment. I'm at work now, so I'll take a look when I get home.

Is the back groove related to the siphuncle?

Speaking of Domatoceras descriptions, some D. species have been moved to separate genera. One is described in this old publication:

http://kuscholarwork...ticle.003op.pdf

D. kleihegei is now called Stenodomatoceras (I believe).

Edited November 13, 2012 by Missourian

[howard_l]

Thank you for the info. I had seen that paper before but I hadn’t read the part about Domatoceras. The Domatoceras in the paper resemble the Miss. KY ones as do plates of Domatoceras from the publication “Fossils of Ohio”.

I found a description in the paper you cited that helps “The ventral side of the outer volution of the holotype is concave throughout all of its length. However, in the adoral half of the living chamber, the amount of concavity becomes very small indeed.” This is what I am finding in my nautiloids, I believe it is termed “Ventral Saddle”.

What I am now thinking is the lower units of the Nancy Member of the Borden Formation contain Epidomatoceras which matches the description from specimens from the lower Mississippian of Ireland and does not have a “ventral saddle”. The larger nautiloids from the Nancy just below the Cowbell (equivalent) of the Borden may be an intermediate between Epidomatoceras and Domatoceras which has a “ventral saddle”.

First five photos are of two specimenes of Epidomatoceras

last two are of what I was calling Thrincoceras kentuckiense that was discribed over a hundred years ago. Note the vertral saddle. a

[BobWill]

All I have is this section of a whorl that has a septum on one end so pre-body chamber. Sorry about the poor pictures...camera went whacky. Please let me know if my ID is wrong.

flank

ventral surface

[Missourian]

Here's the 'back' of the one shown above:

Here's one that looks similar to yours:

Winterset Limestone, Missourian, Pennsylvanian

Jackson County, Missouri

Edge on:

The back is squared off and slightly convex.

I haven't figured out the id of this one yet.

Edited November 14, 2012 by Missourian

[Missourian]

For reference, here's my Stenodomatoceras:

Winterset Limestone

Jackson County, Missouri

[howard_l]

Very nice!!, the first one, I presume Domatoceras is missing most of the living chamber isn’t it. Most of the ventral saddle on mine is on the living chamber. Your is still pretty pronounced even on the phragmocone. I also ran across the genus Aphelaeceras (lower Mississippian) that also has a pronounced ventral saddle but it is in a different family then Domatoceras . Domatoceras is in the family Grypoceratidae and Aphelaeceras is in Trigonoceratidae.

The other Nautiloid you found in the Winterset Limestone looks a lot like the lower Miss. Maccoyoceras that is found in Michigan and very abundant in Madison Co. KY. It is also in family Trigonoceratidae. It could be its great granddad. The back is smooth and slightly rounded. The sutures are very simple unlike the Epidomatoceras, they both are in the same horizons in Madison CO. KY

Post some different views of your Stenodomatoceras.

Photo is of Maccoyoceras

[Missourian]

Very nice!!, the first one, I presume Domatoceras is missing most of the living chamber isn’t it.

Post some different views of your Stenodomatoceras.

It is missing all the living chamber and perhaps more. Those beasts can get to larger than a foot in diameter.

As for the Stenodomatoceras, I'll get more pictures when I can get to it and the camera.

[Missourian]

Howard_L, would you be able to recommend any publications on Pennsylvanian nautiloids? I'm particularly interested in their biostratigraphy, i.e. I'd like to know the stratigraphic range for each genus/species, so I can narrow down the id possibilities of what I've found (and hopefully pick up some new types in the future. ). Up to now, I've id'd my nautiloids from several scattered sources. I'm pretty sure some of the names are no longer valid.

I was hoping to compliment this pub on the biostratigraphy of mid-late Penn ammonoids:

http://www.kgs.ku.ed.../1994/Boardman/

Edited November 15, 2012 by Missourian

[howard_l]

No I am in the same boat, most of the Carboniferous publications were done before I was born, which means they are very old. Some are over 100 years old. There are some reports out of Ireland that have been helpful and I search extensively on the internet but that is uasually not very good. Some of the newest material appears to be coming from Japan. I know people working on Amminoids from the Carboniferous but no one working on Nautiloids. Good luck!

[Missourian]

Yeah. While ammonoids are good for stratigraphic correlation, nautiloids are merely pretty accent pieces.

[Missourian]

Post some different views of your Stenodomatoceras.

[howard_l]

Very nice, you can definitely tell it is in the Domatoceras group. One of the main workers currently out there is from Japan but he has done work in Oklahoma, Arkansas and Texas to name a few areas. His name is Suuji Niko, try looking up his papers. He does a lot in the Carboniferous.