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Crinoids Sharing A Common Stem?


Missourian

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Many years ago, I saw a write-up done by a local collector regarding multiple crinoids found attached to a common stem. It was a description of a 'colony' found in the field. I believe they were Ethelocrinus. They looked something like this:

post-6808-0-32167500-1355623183_thumb.png

I didn't see it myself -- in person or in photos. I'm not sure if it was for real, a misinterpretation, or an outright fabrication or hoax. I've had my doubts, but yet we find many really large crinoid stems that seem to be way too large for the calices we find around here.

Context is critical.

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I'm not sure this is related, but large stems around here tend to have 'cirri' attachments on one side:

post-6808-0-48439800-1355785329_thumb.jpg

Perhaps the large stems were lying flat on the sea floor when living. If multiple calices were attached, they would likely have grown out of the upper side.

Edited by Missourian

Context is critical.

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I have a similar column with two rows of those on one side. It kind of looks like a caterpillar.

I just assumed (shame on me), that they were for anchoring.

Steve

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I just assumed (shame on me), that they were for anchoring.

I'm still inclined to think the same thing (shame on me too :) ), but anything's possible.

Now, I'd like to see what the huge stems would anchor to....

Context is critical.

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Yes those attachment points are just for a root like structure for attachment purposes. I have never heard of crinoids sharing a stem. It could be a possibility that they are talking about free living crinoids. As in they were not stalked crinoids that could move around. So potentially they are just perched on the same item such as a stem from another stalked crinoid. But I guess anything is possible and I would definitely want to see it.

– CQ

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I'm not sure this is related, but large stems around here tend to have 'cirri' attachments on one side:

They don't have to be large to have cirri. I found this specimen on December 4 at Portland Point (Middle Devonian, Moscow formation). Crinoids are pretty rare and puny-looking at this site, but I was pleased to find this fragment with cirri still attached.

post-7334-0-89339400-1355792551_thumb.jpg

post-7334-0-22859100-1355792554_thumb.jpg

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They don't have to be large to have cirri. I found this specimen on December 4 at Portland Point (Middle Devonian, Moscow formation). Crinoids are pretty rare and puny-looking at this site, but I was pleased to find this fragment with cirri still attached.

Maybe I should have called them 'satellite stems' instead. My point was the attachments being present on one side only. I would expect such an arrangement with a sea-floor-hugging large stem with multiple 'satellite stems' and calices. I would think an upright stem would have cirri (or 'satellite stems') extend in all directions.

I put 'scare quotes' around 'cirri' because I'm not sure what they would be called if they had heads on the end. :)

Interesting Devonian stem, by the way.

Context is critical.

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I put 'scare quotes' around 'cirri' because I'm not sure what they would be called if they had heads on the end. :)

'Necks'! :D

Edited by Bullsnake

Steve

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Echinoderms are not an animal that reproduces by any sort of "budding". A two-headed crinoid, let alone nine plus, would be as rare as a two-headed cow. Which is of course to say it could happen.

I think if you follow up on the original article it will either be a dead end (not true at all) or, as suggested, be a reference to the various multiple crinoids that have been found attached logs and branches and presumed to have been drifting in the open sea. Somewhere there is an image of a German(?) specimen on a wall-sized plate. Scroll down for image of crinoids: http://pterosaurheresies.wordpress.com/2012/08/01/tanystropheus-a-bipedal-predator/

And here is a Chinese version: http://fossilology.blogspot.com/2011/11/guanling-lagerstatte.html

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Echinoderms are not an animal that reproduces by any sort of "budding". A two-headed crinoid, let alone nine plus, would be as rare as a two-headed cow. Which is of course to say it could happen.

I think if you follow up on the original article it will either be a dead end (not true at all) or, as suggested, be a reference to the various multiple crinoids that have been found attached logs and branches and presumed to have been drifting in the open sea. Somewhere there is an image of a German(?) specimen on a wall-sized plate. Scroll down for image of crinoids: http://pterosaurhere...pedal-predator/

And here is a Chinese version: http://fossilology.b...agerstatte.html

Yeah. When I saw crinus' post above with the nice little crinoid attached to the stem, I thought of the possibility that the Ethelocrinus described in the paper may have merely snagged on a larger stem. You know how these things can play tricks on the eyes when they are exposed in the field.

And those German and Chinese crinoid plates are some of the coolest fossils in existence.

BTW, if I remember correctly, the 'paper' was probably a write-up in a local club bulletin.

Context is critical.

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My 2 Cents

We've all seen the video of crawling crinoids ....

Modern stalked crinoid breaks away from holdfast and crawls to escape being eaten alive !!

LINK

Many argue this is just a characteristic of only "some" MODERN stalked crinoids

and NO Evidence of this occurring in the fossil record.

I suggest the obvious ... (thinking outside the box)

Stalked crinoids were NOT "Chained" in place for life like plants.

Holdfasts are NOT "Roots"...Simply "temporary" attachment features.

Stalked crinoids in the fossil record had the ability to move,

to one degree or another, and re-attach for a long list of reasons.

If we consider this to be true ... It would answer lots of questions

including source for some odd and interesting traces.

Many say we do NOT have "physical proof" of this occurring

in the fossil record. I suggest we do have proof, however, the proof

has not been interpreted correctly.

Edited by Indy

Flash from the Past (Show Us Your Fossils)
MAPS Fossil Show

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  • 4 weeks later...

They certainly can share a common holdfasts at least, I have a few eucalyptocrinus display this condition.

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