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Winner of the June 2018 Invertebrate / Plant Fossil Of The Month

Cris

By Cris
in Fossil of the Month

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abyssunder Regular Member

abyssunder

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Posted

Congrats, really nice one! :dinothumb:

" We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. "

Thomas Mann

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GerryK Regular Member

GerryK

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On 7/11/2018 at 12:35 PM, FossilDAWG said:

That is a great find, and a great prep job, Gerry.  :wub:

I'm intrigued by the multiple brachioles on that specimen.  Every Pleurocystites I have seen have only 2, but yours seems to have four.  Also, have you considered P. distans as a possible ID?  Tom Bolton described that species from the Farr formation around Lake Temiskaming, which I think correlates with the Prosser (though I am not certain of that).

 

Don

Don

Your comments are very interesting and because I’m not that familiar with cystoids, I’ve been doing some research. I looked up Bolton’s (1970) description of Pleurocystities distans. I also looked up Parsley (1971) description of Pleurocystities distans from the Galena Formation, Stewartville Member of Minnesota. My specimen is found below the Stewartville Member of the Galena Formation in the Prosser Member of Minnesota. I don’t know of any Pleurocystities described from the Prosser. I don’t believe my specimen is P. distans because the theca shape is more elongated than P. distans.

Kolata !1975) describes  Pleurocystities cf. P. squamosus from the  Galena Group, Dunleith Formation of  Illinois and I used his reference for a name. However, my specimen is different from those illustrated by Kolata and it looks more like a Pleurocystities squamosus from Ontario.

As for the brachioles, I believe the specimen does have 2 and not 4. The brachiole is made up of 2 plates and it looks like the plates are separating making it look like 4.

I also attached a picture of another Pleurocystities from the Prosser for comparison. If these 2 Pleurocystities are Pleurocystities squamosus or a new species, some expert will need to examine the Prosser specimens and determine what they are.

Pleurocystoids.jpg

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fifbrindacier Regular Member

fifbrindacier

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Nice echinoderm Gerry.:envy:

theme-celtique.png.bbc4d5765974b5daba0607d157eecfed.png.7c09081f292875c94595c562a862958c.png

"On ne voit bien que par le coeur, l'essentiel est invisible pour les yeux." (Antoine de Saint-Exupéry)

"We only well see with the heart, the essential is invisible for the eyes."

 

In memory of Doren

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Shellseeker Regular Member

Shellseeker

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Thanks for bringing this one back to the present.  Great find and preparation. It is always great to make a find that is really difficult to accurately identify.  Jack

The White Queen  ".... in her youth she could believe "six impossible things before breakfast"

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