Graf Curved Cephalopod

[connorp]

I found this partial curved cephalopod at the famous cephalopod beds (Maquoketa Fm, Upper Ordovician) at Graf, Iowa last year. It is the only non-Isorthoceras cephalopod I have found from here in my several trips. The only other cephalopod I have seen described from this site is Beloitoceras, but I don't believe that is what my specimen is. Has anyone come across anything similar? Thanks for your thoughts.

 

[Tidgy's Dad]

It doesn't look quite like the specimens of Beloitoceras I have seen either. 

But I haven't seen the species Beloitoceras grafense. 

Interesting and a great find, whatever! 

[Crusty_Crab]

Having been to Graf a whopping 1 time, I only found straight cephalopods. However, there are other possibilities other than it being a new taxon, such as: 1. taphonomic deformation or 2. pathology. 

[Al Dente]

Does it have any septa? Not seeing any in the photo.

[connorp]

Oops, this was supposed to be in the ID section. Could a mod move it? @Fossildude19

 

19 hours ago, Al Dente said:

Does it have any septa? Not seeing any in the photo.

No I don't see any either. Maybe just poor preservation? Not sure. I don't know what else this could be besides a ceph though.

 

The ribbing reminds my of Centrocyrtoceras but I don't believe this genus is known from the Maquoketa.

[RuMert]

50 minutes ago, connorp said:

what else this could be besides a ceph

gastropods

[Fossildude19]

57 minutes ago, connorp said:

Oops, this was supposed to be in the ID section. Could a mod move it?

 

 

Done! 

[Tidgy's Dad]

2 hours ago, connorp said:

 

No I don't see any either. Maybe just poor preservation? Not sure. I don't know what else this could be besides a ceph though.

 

The ribbing reminds my of Centrocyrtoceras but I don't believe this genus is known from the Maquoketa.

Yes, the ribbing is external. External features have been preserved but not the inside as far as can be seen. 

So the septa wouldn't show. 

[connorp]

35 minutes ago, RuMert said:

gastropods

I am not familiar with any gastropod present in the area that has ribbing like this. All gastropods I've found in this formation also tend to be quite small (<1cm).

[ChristineR]

I can’t help with the ID, but was wondering if the pattern was consistent with an internal mold of the fragment shown in your last photo? 

[ChristineR]

Beloitoceras seems to display both patterns. 

[piranha]

7 hours ago, ChristineR said:

Beloitoceras seems to display both patterns. 

 

That is not Beloitoceras....that is just a stock image for all the Cephalopoda pages at: https://fossiilid.info/

 

 

 

B. grafense from:

 

Miller, A.K., Youngquist, W. 1949

The Maquoketa Coquina of Cephalopods.

Journal of Paleontology, 23(2):199-204

 

B. thorslundi from:

 

Kröger, B., Aubrechtová, M. 2019

The Cephalopods of the Kullsberg Limestone Formation, Upper Ordovician,

Central Sweden and the Effects of Reef Diversification on Cephalopod Diversity.

Journal of Systematic Palaeontology, 17(12):961-995

[ChristineR]

2 hours ago, piranha said:

That is not Beloitoceras....that is just a stock image for all the Cephalopoda

Well that was a silly mistake, If only it could be my last or my worst. 
 

Thank you!

 

 

[connorp]

I've reached out to an expert on the Ordovician cephalopods of this area. I will update with any replies.

[minnbuckeye]

I also sent your picture to an individual in Iowa who has a KEEN interest in cephalopods. Hopefully he will know definitively. 

 

 Mike

[tombk]

I’m curious to learn what the experts think.