Nautiloid? Help Id please

[FossilDAWG]

I don't think you'll be able to ID that one without a better look at the siphuncle.  It might be an endocerid, but I get more of an actinocerid feel from it.  However without seeing the siphuncle more clearly I can't be certain at all.  Are these fossils silicified?  Could you etch them in dilute acetic or very dilute hydrochloric acid to expose more of the structure?

 

Don

[PaleoOrdo]

I am sorry for the late reply, but I was unable to write because I had an accident which set me out for 2 months. I agree with endocerid or actionocerid. Maybe more likely endocerid because most (or all?) actionocerids have somewhat flat conch?

On 10/15/2021 at 6:46 PM, FossilDAWG said:

Are these fossils silicified?

Yes, I think the last speciemen above is silicified (If I understand the meaning of that as being yellow in color and not show the detail patterns?). As is often with these rocks in the formation, mostly only the surface have a clear pattern (showing connectng rings and bullettes, although some have been too much or partly covered by coars calcite) and not the internal fillings. 

 

On 10/15/2021 at 6:46 PM, FossilDAWG said:

Could you etch them in dilute acetic or very dilute hydrochloric acid to expose more of the structure?

How diluted acetic liquid should it be? 5-7% is that OK? And how long time should it be in this liquid? I appreciate any help as I did not do this before.

[PaleoOrdo]

I not understand clearly what it means to be silicified and how to recognize fossils which are silicified. Is for example these fossils (a rugose coral and a chain coral ), from the same location, sicilified?

[Ludwigia]

1 hour ago, PaleoOrdo said:

I not understand clearly what it means to be silicified and how to recognize fossils which are silicified.

 

Silicified means that the original substance of an object, in these cases fossils, have been altered through pseudomorphosis to quartz. Most fossils were originally made up of calcite, which dissolves in acetic or hydrochloric acid. Quartz is on the other hand impervious to these acids, so if you put a few drops of acid on the fossil and it bubbles, then you know that it is not silicified. If it doesn't bubble, then it is. Dilute is 5%.

[PaleoOrdo]

Thank you very much for the informative answer. I tryed it out with one fossile and it dissolved, so that one was not silicified. Maybe I need be more careful, try step by step, as you suggest, because I let it stay in the acid for 10 minutes. 

If the fossile is changed into quartz, the quality of the speciemens's preservation of detail is dependent on how fine or coarse the quartz crystal are? If coarse, then it is geodized?

[PaleoOrdo]

This autom I found this beautiful nautiloid in a limestone in the Kalvsjøen formation (late Katian). The rock was found on the surface in a field, so it is possible that it was moved from its original location by the glacier (since the rock is rounded) from the north, and therefore maybe from a little older ordovician  formation. The rock divided into two pieces, without destroying the speciemen much, thereby displaying the inner shape of a very black substance. I wonder what this black material is? It is much crystallization on the surface, but the connecting rings's shape is very clear and it seems to show bullettes inside them and, if so, belong to the discosorid nautiloid order. I am not able to ID the family or genus.