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Shells and Shells and Shells Tar River NC


AshHendrick

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I have some shells I collected from the cliffs off the Tar River that I would greatly appreciate some ID assistance on. I got into books and websites and see they are Chesapecten and probably mostly Jeffersonius... but there are some features I don't know enough about to feel 100% in my research - I hope these photos will be clear enough but I can provide more if not. Any assistance/direction would be great! I have several so I will just number them and hopefully that will make replies easier. 

 

1. 

 

 

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fifbrindacier

I won't be able to help you, but i want to congratulate you for sharing your shells with us.:D

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There are a couple of publications you can find online for free that can help you identify these. The first is a chapter named "Miocene and Pliocene Pectinidae from the Lee Creek Mine and adjacent areas" by Gibson in the book "Geology and Paleontology of the Lee Creek Mine volume 2".

 

The second publication is older. It is Julia Gardner's "Mollusca from the Miocene and Lower Pliocene of Virginia and North Carolina." Part 1. Pelecypoda.

 

 

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Thanks Rick, I was hoping they'd help get some ID but it seems no one else wants to help dig into it either, haha! it's a pain to ID these things as a newbie!! Al Dente, thanks! I had already read through the second you noted but I'm going to review the first now! I'm just hesitant on my wanting to be 100% but I will reply with what I'm thinking they are based on what I've read and maybe someone can at least confirm or deny my attempts.

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Enjoyed seeing the finds/pictures. Sorry I cant help with the ID's though. I've got a similar problem with some of the Pectens I have from the Caloosahatchee and Tamiami and other Plio-Pleistocene sediments from down here--coincidentally I had mine laying on the kitchen counter last night and was going thru some similar references scratching my head. You are slightly ahead of me as you got your photographed! Good luck researching...post what you come up with and if I run into anything to offer I'll do likewise. 

 

Regards, Chris 

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My So far initial ID's/Guesses are below - I will also note WHY I thought this to see if any one is willing to take the time to explain why or why not this would be the case - I'm going off of the articles above and some online resources with photos etc.  I'm giving these to some family for christmas presents - nothing like shells a few million years old :) so I'd LOVE to be able to say hey this is truly what it is if at all possible. I have a ton more shells to photograph is these just aren't clear enough/too damaged I can def. do that. 

 

1. C. Septenarius 7 ribs with the center ones being more flattened/pronounced and the striations across are even. 

2. C. middlesexensis? has 11 ribs, they are little wider than the item in photo 3, striations. ears seem uneven and the sinus/base is not as deep/rounded out as the other. 

3. C. madisonius - 17 round, striated ribs, flatter shell with deep sinus and equally sized ears.

4. C. Nefrens? No clue its much more curved than all the others, smooth small round ridges slightly flattened on the top, equal ears and 15 ribs. the ribs are not as pronounced as photo # 5, which I THINK is jeffersonius, and they are both the same size give or take 1 cm in length. 

5. C. Jeffersonius - 9 broad round/flat topped ribs. Little lines between the ribs. My hesitation is the definition of ribs on the inside of the shell seem to be more pronounced toward the base than the examples I've been seeing. Possible C. middlesexensis?

6. C. middlesexensis? has 12 ribs, they are little wider than the item in photo 3, striations. ears seem uneven and the sinus/base is not as deep/rounded out as the other. 

 

hopefully at least ONE of these is right :)

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Looks like you've got the ball rolling. I dont know yet how much help I might be able to provide as I havent had much of chance to dig into this yet at all--maybe this weekend. Hope someone more familiar can jump in sooner. I'd recommend including a scale and suggest sticking with a standard view and orientation like this view from the Fl museum of Nat History for future photos. 

http://www.flmnh.ufl.edu/invertpaleo/display.asp?catalog_number=31888&gallery_type=Florida Mollusca-Bivalvia

 

I actually went out hunting after work as the sun was just going down yesterday and found another 12cm specimen on the edge of a lake that called me to take home. Just what I needed another unidentified fossil. 

 

More as I get some research done. 

 

Regards, Chris 

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  • 2 weeks later...

Hi Ash

 

Chris directed me to your post.  Here is a link to Ward and Blackwelder's original description of Chesapecten and its species W&B LINK. The important concept to remember is that they use different species of Chesapecten as concise stratigraphic index fossils for the Atlantic Coastal Plain.  If you are at the site on the Tar River that I have collected you are in Zone 2 Yorktown Formation Rushmere Member which contains only two species of Chesapecten, C. madisonius and C. septenarius.  C. middlesexensis is a highly restricted species found only in the Upper Miocene Eastover Formation which to my knowledge is not exposed on the Tar River.

 

I find this Tar River site very interesting as there is a lower gray colored layer with C. septenarius and typical 16-20 rib C. madisonius and a denser buff colored layer above containing mostly 10-12 rib C. madisonius.  Lyle Campbell refers to this form as C. madisonius carolinensis Yorktown LINK although Buck Ward does not (personal communictaion).  

 

I hope this helps.

 

Mike

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  • 2 weeks later...

Mike, thanks for the details - I am sort of bummed that there are only two possible species there - and the septanarious seem really difficult to find - unless I am confusing some of the ones I thought jeffersonius that are actually septanarious. These guys are no joke hard to identify from a beginners standpoint - I'm now slightly obsessed with learning about how to identify chesapectin!! I did spend a few hours with George here in town a few weeks ago getting help to ID some of these/learn about them and we most certainly knew I had a lot of the Madisonius but there are a few that really stand out from the two species you noted so I may have to do more reading/research to understand how much variation there really is on that species in identifying it. 

 

Every one else, I really appreciate all of  the articles, i'm saving them ALL, I read most of them and was most certainly "that guy" trying to share my excitement/new knowledge with my Girlfriend who just didn't seem to appreciate (but kindly tolerated, as usual) the characteristic and details involved in learning species of Chesapectin, haha! 

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Two possible species? Two that we know of. Your diligence may lead to discovery of species not known! Then would your girlfriend be surprised when the new discovery is named after her!

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