Ordovician Orthocones

Solius

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Here are a few orthoconic nautiloids that were collected from late Middle Ordovician/early Late Ordovician rocks in Kentucky.

Hoping for an id???


With the lack of visible siphuncle, probably no ID???


 

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Architeuthoceras

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First off, :welcome: to TONMO Solius! Or at least to becoming a non lurker :sly:

The top one has the expanded siphuncle segments of an actinocerid, but the siphuncle is smaller than I'd expect to see in an actinocerid. More study needed for that one. Without a view of the siphuncle the other two will have to remain orthoconic nautiloids unless we can find some papers on the nautiloids from the formation you found them in.

Very nice fossils, thanks for posting them.
 

Solius

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Hmmm... I thought that I had responded to the thread??? The interweb monsters must've eaten it.

Anyway, thanks for the welcome.

The top one has the expanded siphuncle segments of an actinocerid, but the siphuncle is smaller than I'd expect to see in an actinocerid.

I have a few actinocerids and the siphuncles, of them, are about 1/4 to 1/3 the width of the phragmocone. They are stored in a warehouse, and I don't have photos on the hard drive, but the next time that I am out there, I will try to find them.

Once again, thanks for the welcome.
 

Solius

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Here is a nautiloid that I recovered from a rather strange bed early Late Ord rx from Central Ky. The bed is composed of, almost entirely, nautiloids and asaphid trilobites remains-- molts and some whole ones(one of the juvenile trilobites appears to have had a bite taken out of it).

The photo on the right(magnified and better lighting) appears to have part of the external shell structure preserved???

I have found some bivalves in the same bed with parts of the original shell material preserved... color and all!


Orthocerid w/preserved shell structure by solius symbiosus, on Flickr
 

Terri

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Fun! Trilobites and cephalopods what more could you ask for? I tried to enlarge the pics. on Flicker with no luck, do you think we could get an enlargement?
 

Architeuthoceras

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If you can see a cross section, make sure this isn't the endosiphuncle of an endocerid. Many times the endosiphuncle (or endocones) are replaced with sparry calcite.

Nice fossil :cool2:
 

Solius

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Terri;196599 said:
I tried to enlarge the pics. on Flicker with no luck, do you think we could get an enlargement?
That photo is from a few machines ago. I probably have it on a hard drive, somewhere. I'll see if I can find it.


Architeuthoceras;196618 said:
If you can see a cross section, make sure this isn't the endosiphuncle of an endocerid. Many times the endosiphuncle (or endocones) are replaced with sparry calcite.

Nice fossil :cool2:

What you are seeing is, what was, the external surface of the phragmocone. The sparry calcite is a sub-surface artifact illuminated by the light source.
 

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