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Post by pleecan (Peter Lee) on Oct 16, 2012 18:58:06 GMT -5
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Post by pleecan (Peter Lee) on Oct 16, 2012 21:22:07 GMT -5
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Post by pleecan (Peter Lee) on Oct 17, 2012 7:56:13 GMT -5
General consensus by 3 people is crinoid.
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Post by Joe Botting on Oct 17, 2012 8:26:24 GMT -5
I'm trying to work out how 3D this is... is it a section through something cylindrical, or is it effectively a flat, but wrinkled sheet? If the former, then yes - a crinoid or cystoid with spinose columnals is pretty likely. If the latter (and this is my hunch at the moment, looking at the shadows) then you're looking at palaeoscolecid. The worm interpretation would make more sense with being in a burrow as well, of course.
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Post by pleecan (Peter Lee) on Oct 17, 2012 10:30:17 GMT -5
I was hoping for a palaeoscolecid.... the object is sitting in an infill as some of the infill fell out leaving a 1/8" up depression hence the burrow idea... it could be a wrinkled flat sheet with cuticle exposed ... maybe... will have a better look tonight : )
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Post by pleecan (Peter Lee) on Oct 17, 2012 19:08:07 GMT -5
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Post by pleecan (Peter Lee) on Oct 17, 2012 20:23:31 GMT -5
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Post by pleecan (Peter Lee) on Oct 17, 2012 20:25:06 GMT -5
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Post by pleecan (Peter Lee) on Oct 17, 2012 20:27:03 GMT -5
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Post by pleecan (Peter Lee) on Oct 17, 2012 20:31:04 GMT -5
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Post by Joe Botting on Oct 17, 2012 21:00:48 GMT -5
I'm getting more persuaded by palaeoscolecid, Peter. The critical thing is that the tiny discs are made of a darker material than the surrounding, rather than just being in shadow, and I think in most cases at least, the rows are paired, with a depressed band between pairs. This is what you expect with palaeoscolecids, as you have (usually) transverse annulae each with two rows of phosphatic plates. In places you can't see the 'plates' clearly, probably because it seems to have been partly infilled with a sheet of calcite that is obscuring a lot of the details - bit in other areas they are fairly clear.
Now the clincher would be an array of little nodes on the plates themselves (as in Palaeoscolex). There should also be a very fine array of microplates on the surface between the plates, but you won't get an image of that without SEM.
If it does end up as palaeoscolecid then it's very interesting - I don't know of any Late Ordovician ones, although there are a couple from the Late Silurian.
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Post by pleecan (Peter Lee) on Oct 18, 2012 4:32:10 GMT -5
Thanks Joe for the Diagnostics... this is indeed exciting.... I have not yet reached the highest magnification yet.... will try this tonight with the same optical configuration as used to image the sponge spicules early in the year.....
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Post by ammocarbsteve on Oct 18, 2012 7:20:11 GMT -5
Peter....Thats stunning, it really is... I need to scale down my search a bit I'm certainly missing lots of very interesting things... In a burrow... wow...
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Post by pleecan (Peter Lee) on Oct 18, 2012 7:32:56 GMT -5
Thanks Steve... managed to take a few shots on the new optic configuration at higher magnification.... will continue tonight... will be posting shortly.
PL
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Post by pleecan (Peter Lee) on Oct 18, 2012 8:59:18 GMT -5
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