Cephalopod?

[grg1109]

This looks like a Cephalopod to me...but I've yet to identify it.  I wonder how...if they were "cone" shaped...how this could be so flattened and yet keep it's "rings" in such good condition.  There is an indentation (blue line) in it's "middle length".  The edges are almost knife like while it's middle is approx. 1/16" thick.

Thanks

Greg

[Kane]

Nice nautiloid! Indeed, it is one, and they can sometimes appear flattened (particularly in shales). Nautiloids in limestone maintain their more robust appearance. Shales flatten everything.  

 

I'm a but fuzzy on nautiloid identification to species level (and I usually get them mixed up  ), so I'll defer to @FossilDAWG. 

[Fossildude19]

This looks like a Spyroceras sp. 

Probably Spyroceras nuntium. 

 

[grg1109]

5 minutes ago, Fossildude19 said:

Probably Spyroceras nuntium

Actually I saw this one and was my top consideration.  I could not however figure out how if it started in this shape shown, the fossil could be so flat.  Kane answered this...although it seems such a strange alteration.  I'm not very proud of my "prep"(air scribe) work on this...the layers of rock broke away so easily and at surprising times and ways.  This is the best my skill set could do.  But, having said that...it's a prize for me indeed!

Thanks Very Much

Greg

[val horn]

i think when talking about a devonian cephalopod  400mya that is a lot of time and a lot of weight sitting on the fossil compared to a cretaceous fossil of "only" 80 mya to help account for that degree of flattening.

[FossilDAWG]

Regarding the flattening, keep in mind that the camerae (chambers) were hollow, so they can compress a lot unless the shell is broken so as to admit sediment into the camerae before the sediment is dewatered and compressed into shale.  Fossils in shale commonly are flattened as each mm of shale likely represents cms of initial sea floor sediment.  The fold along the length of the specimen is further proof of flattening; think of what happens when you flatten a cardboard tube from an empty paper towel roll.

 

As far as the ID is concerned, the ribbed appearance of the side view does suggest Spyroceras.  However, the ribs seem to coincide with the septa (the parts of the shell that separate camerae).  The septa would strengthen that part of the shell and make it harder to flatten, so they could stand out and make "ribs" as an artifact.  The question could be resolved if the position of ribs actually does (or does not) correspond to the suture line (the line formed where the septa meet the exterior of the shell) in Spyroceras.  My recollection is that they do not, but I will have to double check on that.

 

Don

 

 

[Kane]

It's a lovely piece, so kudos on what you were able to do in terms of prep! I wanted to say Spyroceras, but I've wrongly attributed that in the past as it is contingent on the ribbing. From here, I would say you can stabilize it with super glue (or paraloid if you have the means!). But what Tim and Don say above is fairly key to understanding this attractive specimen in its current state.