Plectronocerids and other neat nautiloid fossils

Architeuthoceras

Architeuthis
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willsquish

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I love the second pic there. Interesting and not too easy to find group, the 'Intejocerids' .


Architeuthoceras;122253 said:
I can imagine how hard it would be to notice fossils where the replacement mineral is the same color as the matrix.

Yeah, I ended up using an exacto to remove a millimeter or so to get a faint remenant of the pre-weathered/assimilated shell on the other ascocerid, so I could reconstruct the other 2 septa. It's a weird shape, since the rock angles back mid way up.
 

Nauti-guy

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Plectronocerids in New Mexico

willsquish, I hope you were able to obtain, at least access to, the two references given by Architeuthoceras. Another good reference that covers more recent findings in China is that by Curt Teichert, 1988, Main Features of Cephalopod Evolution, Volume 12 Paleontolgy ad Neontology of Cephalopods, Clarke and Trueman Eds, in The Mollusca, Academic Press.

Regarding plectronocerids in New Mexico, I believe there aren't any. The nearest are found in the Trempealeauan (U Camb.) San Saba Ls. in central Texas. The Lowest cephalopod bearing formation in New Mexico is the upper Gasconadian Sierrite Limestone of the El Paso Group. Cephalopods reported in the literature (Flower) include Ellesmeroceras, Clarkocers, and Ectenolites. The underlying Bliss formation is a near shore sandy deposit with some brachs and trilobites, but to my knowledge no cephalopods. The Bliss extends into the Lower Ordovican from the Cambrian, the boundary determined by graptolites.
 

willsquish

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plectronocerids

Nauti-guy;124858 said:
willsquish, I hope you were able to obtain, at least access to, the two references given by Architeuthoceras. Another good reference that covers more recent findings in China is that by Curt Teichert, 1988, Main Features of Cephalopod Evolution, Volume 12 Paleontolgy ad Neontology of Cephalopods, Clarke and Trueman Eds, in The Mollusca, Academic Press.

Regarding plectronocerids in New Mexico, I believe there aren't any. The nearest are found in the Trempealeauan (U Camb.) San Saba Ls. in central Texas.

Yep, I ordered the references and read through. When next I get a suitable vacation time, I'll try to get down to san saba. Back to school for now, though.
 

vw1

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willsquish;122139 said:
Here's my touchup of the vuggy one. Very hard to see the many of the sutures unfortunately. The rock in which all these were found is limestone, and so calcite structures, when exposed to weathering end up blending in perfectly.

Does it become clearer if the specimens are wet?
 

willsquish

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cambrian cephs

Update. Yes here they are. Some plectronocerid, cambrian cephalopods.

The one triangular larger one on the right, I believe, is a palaeoceras. The white portion is just over one inch in length. The rock and lichen did interesting effects that made these pop out a bit. The chambers clearly got more filled with calcite, which apparently these lichen don't like (liche?). And these are left uncovered. Other chambers closer to the end and the living chamber filled with the surrounding matrix and got more degraded and colonized. One can see a faint outline of the wall of the living chamber on the palaeoceras.

The one somewhat large sliver of white, with a second sliver of white to the left of the palaeoceras along with the faint outline in the matrix there, I believe is a plectronoceras.

There's a small sort of very small slender fellow below the one on the right, which may be a balkoceras, or one of the not-quite-cephalopods that also happened at the end of the cambrian. Ones with chambers but no siphuncle.


Only cephalopod order left to find is intejocerida. Like Rossoceras Any suggestions?
 

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Architeuthoceras

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willsquish;140635 said:
Update. Yes here they are. Some plectronocerid, cambrian cephalopods.

Nice fossils :smile: Can you see any signs of the septa, or are they too thin? Are there a few trilobite parts floating around on that rock, or are they brachiopods?

willsquish;140635 said:
Only cephalopod order left to find is intejocerida. Like Rossoceras Any suggestions?

In the Juab Formation around Fossil Mountain, in the Southern Confusion Range, Utah, Rossoceras is fairly common. :cool2:
 

willsquish

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Architeuthoceras;140650 said:
Nice fossils :smile: Can you see any signs of the septa, or are they too thin? Are there a few trilobite parts floating around on that rock, or are they brachiopods?

The septa are fairly faint on this, but when wet, they can be seen. In the pic you can see some very faint ones from shadows on the calcified portion, and from the shadows in the matrix. Another specimen which seems to have mostly balkoceras has more visible septae. There are some gastropod curls in this rock, as well as some brachiopods. There is at least a pygidium I see on the block I've not photographed yet which has primarily balkoceras (and/or possibly kygmaeoceras, still working it out). And some other trilobite bits on rocks from the same location as this piece, a bit lower down.

Rossoceras is common? Know anyone who might trade? The road trips, while fun and adventurous, take awhile to save up time to go on, with research as it is.
 

Architeuthoceras

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OK, I can finally see a few, they are faint. :oops:

willsquish;140651 said:
Rossoceras is common? Know anyone who might trade? The road trips, while fun and adventurous, take awhile to save up time to go on, with research as it is.

I'll see what I can do. :wink:
 

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