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Arkona Devonian Star Shaped Fossil Object 1Mm:


pleecan

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Here's one that I found; however Silurian in age, that's quite similar as well. I still dont have a possitive ID on my fossil.

Rob:

That is a neat looking starfish like or crinoid like fossil.... the shapes are similar

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For Comparison here is a star shaped crinoid section from Arkona: Imaged with 10X objective and Nikon 995, mag is around 30X net.

post-2446-0-12845700-1295317635_thumb.jpg post-2446-0-75301600-1295317659_thumb.jpg

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For Comparison here is a star shaped crinoid section from Arkona: Imaged with 10X objective and Nikon 995, mag is around 30X net.

post-2446-0-12845700-1295317635_thumb.jpg post-2446-0-75301600-1295317659_thumb.jpg

Good find.

As you can see, these are nothing at all like the image of the star shaped item in the OP (well, except for that they are star shaped).

However, these do indeed resemble what I would expect in crinoid columnals. Even the lumen holes seem crinoid-like.

.

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Good find.

As you can see, these are nothing at all like the image of the star shaped item in the OP (well, except for that they are star shaped).

However, these do indeed resemble what I would expect in crinoid columnals. Even the lumen holes seem crinoid-like.

I wonder if unknown indeed it is a baby starfish..........

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More star shaped micros from Arkona....

post-2446-0-24264800-1295658271_thumb.jp

I wonder whether that might be a sponge spicule?

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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really, really cool looking, whatever it is

nice scope work!

.

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scale in avatar is millimeters

____________________

Come visit Sandi, the 'Fossil Journey Cruiser'

____________________

WIPS (the Western Interior Paleontological Society - http://www.westernpaleo.org)

____________________

"Being genetically cursed with an almost inhuman sense of curiosity and wonder, I'm hard-wired to investigate even the most unlikely, uninteresting (to others anyway) and irrelevant details; often asking hypothetical questions from many angles in an attempt to understand something more thoroughly."

-- Mr. Edonihce

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Auspex , TqB and Crinus.... thanks for your ID consensus.. sponge spicule on the 6 arm star object.

PL

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No mystery, first one is a crinoid stem section, second is a sponge spicule, which is far rarer, one must be looking very closely indeed at one's specimens to spot those little ######.

Very nice camera work. You should be submitting to the UMMP image database.

B

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More star shaped micros from Arkona....

post-2446-0-24264800-1295658271_thumb.jpg

Peter, I've found many of the same objects in my Arkona sediments and they are indeed Sponge spicules.

-Dave

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Peter, I've found many of the same objects in my Arkona sediments and they are indeed Sponge spicules.

Thanks for the ID Dave.... any ideas on the first unknown 1mm star shape object or is that one also a spicules form a sponge?

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No mystery, first one is a crinoid stem section, second is a sponge spicule, which is far rarer, one must be looking very closely indeed at one's specimens to spot those little ######.

Very nice camera work. You should be submitting to the UMMP image database.

B

Thanks for your input! The ROM viewed the first unknown as non crinoid.... they don't know what it is...

ROM Analysis:

"Anything with that kind of regular pentameral symmetry should be of echinoderm origin (as you no doubt know!), but because it's so small and there's no central lumen, a crinoid columnal identity seems unlikely. Dermal sclerites of holothurian echinoderms - the group that includes modern sea cucumbers - are about the right size, but I'm not aware of any that have such a strict stellate morphology. One thing that concerns me a little is the mineralogy of the piece ... it doesn't look calcitic, which would be the case if it comes from an echinoderm. Instead, it has a kind of siliceous appearance, so I'm not ruling out an aberrant sponge spicule as a remote possibility (sponges don't normally have pentamerous spicules)."

PL

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Thanks for your input! The ROM viewed the first unknown as non crinoid.... they don't know what it is...

PL

I think they are wrong. I still believe that it is a piece of Decorocrinus that has minerals growing it and thus obscuring the center hole.

Crinus

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I think they are wrong. I still believe that it is a piece of Decorocrinus that has minerals growing it and thus obscuring the center hole.

Crinus

Good point...

PL

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As for the composition, is it not possible that something that was originally eg. calcite would have dissolved and the cavity filled in by silica or something else, or is it always the case in that particular formation that things have retained their original composition?

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No mystery, first one is a crinoid stem section

Not sure how you can be so certain.

Please give your explanation of the item in question.

As for the composition, is it not possible that something that was originally eg. calcite would have dissolved and the cavity filled in by silica or something else, or is it always the case in that particular formation that things have retained their original composition?

I can convince myself that a lumen was present and has been infilled.

Well, it kinda seems like stretching to make something be something that we want it to be, but this (the combination of these two ideas from Wrangellian and mattdevereux) is the most plausible explanation we have on this one yet - if we're going to say that it is a crinoid columnal.

I would still like to see more from this formation. If this is indeed a pseudomorph (silica-after-calcite in a crinoid columnal whose lumen has been filled in and lost somehow throughout the 'pseudomorphication' ;) process), I would think there should be other silica-after-calcite-pseudomorphs (either of the same organism, or others) to be found in the same formation.

So, is there any evidence of other silica-after-calcite-pseudomorphs in the same formation?

.

____________________

scale in avatar is millimeters

____________________

Come visit Sandi, the 'Fossil Journey Cruiser'

____________________

WIPS (the Western Interior Paleontological Society - http://www.westernpaleo.org)

____________________

"Being genetically cursed with an almost inhuman sense of curiosity and wonder, I'm hard-wired to investigate even the most unlikely, uninteresting (to others anyway) and irrelevant details; often asking hypothetical questions from many angles in an attempt to understand something more thoroughly."

-- Mr. Edonihce

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Arkona Devonian sediments...... Found this interesting star shaped object size = 1mm.... What is it?

post-2446-0-90645000-1294626620_thumb.jpg

Calibrated scale= 3mm diameter

post-2446-0-10677500-1294626751_thumb.jpg

Doubtless the star-shaped fossil has been satisfactorily i.d'd by now, but it looks to me like a Bryozoan, spcifically Evactinopora radiata....just my two cents worth...

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