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Glen Dean Fm., Ky Crinoids And Blastoids

matt cable

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I purchased this piece unprepped this spring at MAPS. The seller has a very unique hunting spot in the Glen Dean Fm. of Kentucky that produces Pentremites blastoids with color patterns. The current theory is this is an indication of a color pattern from when the animal was living. I own a few because they are just that cool.

I just finished removing a lot of rock. When I picked up this piece only one side of the blastoid was exposed. What I didn't expect was the two crinoids on this piece. He had already cut the piece down and went through the calyx of the bottom one. I've done some searching and found a paper from University of Indiana about Glen Dean Fm. crinoids. I'm still not confident about the IDs though. I know the top one is a flexible, but it doesn't look like the Onychocrinus in the paper.

Can anyone help me ID?





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Nice specimen! The KPS link might be able to identify them for you.

"Absence of evidence is not evidence of absence"_ Carl Sagen

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" I think, therefore I collect fossils." _ Me

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes

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The top crinoid resembles some of the Platycrinites I have collected in New Mexico. The plate arrangement to the level of the arms is characteristically simple,just basals and large radials, with no interradials. It's not a flexible crinoid, which is why it doesn't resemble Onychocrinus; I think it's a monobathrid. I don't have any suggestions about the second crinoid.

Very nice "bonus" specimens!


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I'll ask KPS, Herb.

Thanks for your input, Don.

I did a a little more searching and I think the bottom crinoid is a Tholocrinus spinosus. I have a loose specimen and they usually have spines coming off the anal plate. It almost looks like a spiny chimney hat. I think this specimen is just missing the anal tube or it buried deeper in the matrix.

I'll keep working on the top crinoid ID. :)

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Question for you Archimedes....any idea on the species? I did some searching on JSTOR and found three species of Hyrtanecrinus described in a paper by Broadhead and Strimple. H. girtyi, H. diabolus and H. Inflatus are in the paper and all seem to have decoration on the calyx plates and were found in Illinois or Missouri.

I found a mention of a fourth species H. pentalobus, but it looks like it may have also been originally called Cotyledonocrinus pentalobus. The specimen was described in 1860 by Lyon and Casseday and was from Grayson Co., Kentucky. That's really the only information I've found on it. I haven't found a description or diagram, so I don't know if this is a possibility.

Any thoughts?

Thanks again for your help.

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  • 2 weeks later...

I think your crinoid is Hyrtanecrinus pentalobus. The other crinoid is Tholocrinus spinosus. Awesome plate!

I like crinoids......

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