Bear Gulch orthocones | The Octopus News Magazine Online
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Bear Gulch orthocones

Terri

Sepia elegans
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#4
Beautiful fossils!I don't think I've seen preservation like this in orthocones before. :cool: Is that link broken or is it just me?:heee:
 

Hajar

Haliphron Atlanticus
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#12
Thanks Jean. I like this paper too Terri and Solius. I've still not seen Mehl's paper on the Silurian Michelinoceras with arms.

I wonder if perhaps early dissolution of the shell could be an explanation for the lack of obvious crushing and breaking Kevin

Here attached is a closeup of part of the group of orange objects in the smooth-shelled orthocone (95 mm long), field of view about 2.5 mm so they're tiny. The arrowhead-shaped one looks a bit like a rhachidean tooth and there are several more elongate structures reaching about half a mm long in that area. I'm not sure. It would be great to find an articulated radula in these rocks.
 

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Hajar

Haliphron Atlanticus
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#15
Great thought Kevin. I just found my old UV lamp again and the only thing that lights up (apart from a few scattered dust particles) are the robust-looking phosphatic structures in both of these orthocones. Tempting to think of these as beaks, but in the strongly ribbed individual there's a carbonized structure in front of that which is similar to what I think has been interpreted as mandibles in the coiled nautiloids of Bear Gulch. CT and Xradiography could show something, but contrast in these specimens will be less than in the cases of pyritized fossils in mud rocks.
 

Hajar

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#17
Just one more picture from the Mehl paper - the supposed pair of tentacles. I wonder if these could be trace fossils since there seem to be some other horizontal burrows on this bedding plane.
 

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Terri

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#18
Cool! I had a feeling you would come up with that paper. :smile: I really wanted to see the pics. of the as you put it "supposed tentacles". I'm definitely not an expert on these things but (without seeing a closer view) I agree they do "appear" to be conveniently placed burrows. Still intriguing....one of my dreams to find some sort of tentacle trace.
 

Hajar

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#19
A little disappointing isn't it? I've seen the paper referenced as saying that there are ten arm impressions, but actually it says that two large tentacle impressions are in evidence and that an eight-armed plus two-tentacled ("10 Fangarme") beast is plausible. Keep looking !
 

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