Ordovician in Tennessee (Help!)

**Terri** · Dec 20, '09, 9:28pm

Could anyone help me identify this fossil?

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**Architeuthoceras** · Dec 20, '09, 9:50pm

to TONMO Terri,

It looks like the siphuncle and a couple of chambers of an orthoconic nautiloid.

Some very much like it shown in This Thread.

Nice find.

**Terri** · Dec 21, '09, 12:10am

Thanks for the welcome and the info!

**bagarius** · Dec 21, '09, 8:17am

Why is it that when people attach stuff like this I can never see the attachment? I'm assuming she attached something anyway from the contexts of the above posts...

OB · Dec 21, '09, 6:34pm

Can't see it either

**Architeuthoceras** · Dec 21, '09, 7:19pm

I just happened to save a copy. Hope you dont mind Terri.

**Terri** · Dec 21, '09, 9:49pm

Thanks for saving my picture Kevin, I am technologically challenged!

**Architeuthoceras** · Dec 21, '09, 11:36pm

Looks like a fairly large fossil Terri, could you tell us where you found it?

**Terri** · Dec 22, '09, 10:23am

I actually found it in my backyard! I live in the Nashville basin area about 25 miles NE of Nashville, about 5 miles from the Cumberland river. Please excuse my lack of knowledge (total amatuer). I am guessing Ordovician. The fossils I am finding in the same area all seem to be common to this area and the ordovician period. I am trying to learn identification as I uncover the rock that contains all these fossils, so again forgive my ignorance. I have more pic. if you are interested, it may take a few days before I can post them.

**Architeuthoceras** · Dec 22, '09, 1:57pm

Yes, post more pics.

Some fossils from the Nashville area
I think their Trilobite is actually a cephalopod

**Hajar** · Dec 23, '09, 10:27am

I have a specimen a bit like this from Oklahoma. Endoceras sp., 14 cm, Poolville Member, Bromide Formation, "Blackriverian", Ordovician, Dunn Quarry, Criner Hills, Carter County, Oklahoma.

I made this little Bromide Formation sketch years ago, http://rusmithsgallery.fotopic.net/p47950992.html, but probably wouldn't show all those little Nautilus-style tentacles now given evidence from radulae to suggest that the orthocones could have been more closely related to ammonoids and coleoids (Gabbot 1999).

**Terri** · Jan 26, '10, 12:22am

Here are a few more pictures, if anyone can help with identification I would appreciate it. Thanks Kevin and Hajar for the links and photos on previous post. These were found at the same location and the best I can do on that is, Ordivician (lower to middle?), Stones River Group, Wilson County, Tn.

**Hajar** · Jan 26, '10, 7:45am

That top image beautifully shows the great big segmented siphuncle of Actinocerida, quite unlike my endocerid above.

**Architeuthoceras** · Jan 26, '10, 9:37am

I agree with Hajar, the first and third pics are of Actinocerids. Some very nice fossils for being as old as they are

The others may be Endocerids, but to know for sure you would have to slice them up and see if there are endocones inside the siphuncle (or find some that are naturally sectioned). There are a lot of Ellesmerocerids that have a ventral or marginal siphuncle, and they look just like Endocerids until you see the inside.

I will have a look at the Treatise later and see if I can get a better ID.

Edit:
I looked through the Treatise, and I'm afraid there are just not enough visible characters to ID the fossils better than just Actinocerida

**Architeuthoceras** · Jan 26, '10, 11:57pm

Look in the local University Library for a copy of this book.

Wilson, C.W., Jr., 1949, Pre-Chattanooga stratigraphy in central Tennessee: Tennessee Division of Geology Bulletin, v. 56, p. 1-407.

Its old, but should help

**Terri** · Jan 27, '10, 9:37am

Thanks again Kevin and Hajar! I will definitly see if I can find the book you suggested Kevin. I may also attempt to slice one of the possible Endocerids, will post picture if successful..

**Terri** · May 16, '10, 12:19am

Hello Kevin! I am really curious about this fossil, I don't have a clue if it is ceph related or not. It isn't a very good picture, if it EVER stops RAINING I will go back and get coordinants and better pics. It's in Smith Co. Tn. on an outcrop that's about 30 ft. high. The fossil is about 3 1/2- 4 ft. long (guessing).

**Architeuthoceras** · May 16, '10, 1:08pm

Hey Terri !

I don't quite know what to make of that! If it is a cephalopod it is a very large one. I see similar things in the Ordovician out here, they are Sponge reefs, but they don't have the concentric form. It may also be some kind of sedimentary structure where the mud has slumped. Maybe some close-ups of the "septa" would shed some light on it.

Hope the rain quits soon, keep to the high ground

**Terri** · May 17, '10, 6:33pm

Interesting...I wouldn't have guessed sponge reef, after a little googling I found a picture of an Ordivician sponge reef that was similiar, but like you said without the concentric form. I did find another picture which is only slightly better but may show you more. I will be able to go out at the end of the week for closer shots. Pretty sure this will end up being: Nashville Group: Bigby Cannon Limestone.

Thanks Kevin

smile:

**Architeuthoceras** · May 17, '10, 11:49pm

If you go get more pictures, try to get a close-up of the structure in the upper right of the last photo. It looks like whatever it was collapsed and broke-up, (it looks alot like septa would look when they break) very cool! Also maybe get a view of the left side so I can see how the other end looks. Are there any fossils in the surrounding rock or in or on the concentric rings?

I will be away collecting next week and I don't know if I will have internet access so you may have to wait for comments on the next photos