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Sometimes you get a very pleasant surprise when you get your finds home and start prepping. I was very fortunate to find two relatively complete Amecystis laevis this Saturday October 31, 2015 up at the JD Quarry near Lake Simcoe, Ontario , Canada. They most likely came out of the very top part of the BobCaygeon formation as they were both found in a recently created pile and not in situ. If not it was from the very bottom of the Verulam

This picture because of the lighting used came out a bit blue. I am not the best photographer around.

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The specimen is on an 85mm * 66mm matrix and is 79 mm long from tip of arm to tip of tail (about 3.1 inches) . The theca on the amecystis is 17mm wide by 22 mm long.

The Amecystis is a dorsal orientation.

The edrio is approximately 6 mm in diameter.

I believe this to be a Amecytis laevis (Raymond) by the way Thanks for the correction Kevin (Northern Sharks) there are definitely no pore rhombohedrons on this specimen. It is a shame that the Amecystis and the edrio both have some slight damage to them from the quarry blasting. But they are still very good specimens. The amecystis is fairly well inflated and nicely colored. Here is a better picture showing the true coloring.

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But to my surprise it has a very nice attached travelling companion in a edrioasteroid which I believe to be an Isorophusella incondita.

What makes this super interesting and probably quite rare is the fact that the edrio is attached to the amecystis and may well have been there when the amecystis was alive. I wonder if anyone else has ever come across this particular association. Edrios are often found attached to brachiopods in this locality.

This was prepped using 40 micron dolomite under a zoom scope at 22 PSI using a Comco .018 high precision nozzle on a Comco air abrasion unit.

Edited by Malcolmt
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Can't answer the question, but that is a sweet fossil!!

Love it much!!!

Tony

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Here is the specimen so that you can see the whole of the matrix it is on. The specimen is on an 85mm * 66mm matrix. About 3.5 by 2.5 inches

post-4886-0-23541800-1446508833_thumb.jpg

Edited by Malcolmt
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Wow - very nice!

I was always fascinated by the BobCaygeon formation, but never made it to this area. But it is still on my list - never give up!

If I can't go now I might have to visit this place later on in a wheelchair. But I will go!

Thomas

Edited by oilshale
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excellent find. No, I know nothing about the life history of these things.

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Honestly, that is one of the coolest fossils I've ever seen! I love it! Congrats.

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Awesome, Malcolm!

Congratulations on a fantastic find and prep.

Gotta love the hitch-hikers!

Regards,

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I recall that Peter Lee had a similar Pleurocystites/Isorophusella association specimen, there is a photo somewhere here in the Forum. There is also a paper (Sumrall, 2000) that describes the biological implications of an edrioasteroid attached to an Amecystis, which is also a pleurocystid.

So not totally unique, but exceptionally rare and excellent nonetheless.

Don

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A hauntingly, beautiful find and prep...thanks, Malcolm.

:o

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Don, that is an excellent paper, thank you for linking to it.as I had not seen it before. I will likely contact the author (I did send him an email) with pictures of this find because the pictures of this one are better than the ones he has in the paper of the Amecystis. Amecystis are also found in this locality and Kirkfield where the specimen in the paper was collected is about a 20 minute drive away from this locality. Again as in the paper cited this would have the periproct side down. For the edrio to feed the attachment would have to be on the dorsal side. This would perhaps suggest an epifaunal life mode. Cystites of any form when well preserved have always been one of my favorite Ordovician fossil groups.

P.S. Don tried to find the Peter Lee post but could not find one here.

Edited by Malcolmt
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What a stunning specimen.

Needs to be submitted as find of the month....year!!!

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Here is Peter's specimen (1st post of the thread). It actually has 2 edrios attached.

You guys are so lucky to even have the chance to collect such fossils. I really like (and miss) the Southern Ontario Ordovician, there are so many strange and wonderful critters to hope to find.

Don

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Thanks Don for the reference back to Peter's specimen.

I wonder what the percentage of amecystis and pleuro's at this locality have edrio's attached. Until last year pleuro's at this locality were not all that common. I was only hearing of a few being found each year. We now have a small area that seems to be producing them in reasonable amounts along with poorly preserved ceraurus. Amecystis still appear to be quite rare compared to plero's .We are also pulling out a fair number of crinoids of different species (Isotomocrinus, Daedalocrinus, Reteocrinus, Carabocrinus, Cupulocrinus) from this same area.

As for the pleurocystites, I know of about 12 found last year and probably about 20 to 30 found this year. Most are incomplete (very difficult to find with the arms complete or the stem intact to its endpoint) with preservation similar to this one. This locality is very "pocketed" with specimens and is not evenly distributed by any means. You will find a cluster of one species in a very small area. Last year I found a cluster of about 20 homocystites and am aware of some clusters of glyptocystites and syringocrinus being found in the last two years.

Edited by Malcolmt
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Northern Sharks

Hi Malcolm: I'm pretty sure your cystoid is an Amecystis laevis unless by sheer fluke all the pore rhombs were damaged. A Pleurocystites has 2 pore rhombs near the arms and on near the tail. Amecystis has none. Great fins by the way. Hopefully I'll be up there this coming Saturday.

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Honestly, that is one of the coolest fossils I've ever seen! I love it! Congrats.

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Kevin thanks I will look closely under the scope and in my Hessin and reevaluate what it is.

Well just looked and it is definitely an amecystis Laevis..... good catch

Edited by Malcolmt
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I recall that Peter Lee had a similar Pleurocystites/Isorophusella association specimen, there is a photo somewhere here in the Forum. There is also a paper (Sumrall, 2000) that describes the biological implications of an edrioasteroid attached to an Amecystis, which is also a pleurocystid.

So not totally unique, but exceptionally rare and excellent nonetheless.

Don

Don on closer inspection and thanks to Kevin pointing it out this was not a Pleuro but was in fact an amecystis just like what was described in the paper you cited.

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Don, now that I closely look at Peter's specimen ( http://www.thefossilforum.com/uploads/monthly_12_2009/post-2446-12609200493151.jpg ) with two edrio's attached I am thinking that his is also an amecystis and not a pleurocystis. Kevin your thoughts????

Edited by Malcolmt
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I do think Peter's specimen is also an Amecystis. I wondered about yours as well, but since you seemed to be so certain it was a Pleurocystites I just assumed the pore rhombs had been broken off.

It's interesting that Pleurocystites is the most common cystid in the Ottawa area, but I never saw an Amecystis there, and it is not mentioned in Alice Wilson's monograph on the echinoderms of the Ottawa Formation (now the "Ottawa Group"). However it seems to be not uncommon in the area around Lake Simcoe. I wonder what was different about the environment that allowed pleurocystids without respiratory structure to flourish in one area and be totally absent in the other.

Don

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Northern Sharks

I agree. While Peter's is a lot more damaged, it also looks more like Amecystis.

Don, how common are Glyptocystites and Homocystites in the Ottawa area? We have also found both of those in this same quarry.

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Beautiful specimens!!! I love it whenever there are multiple species associated together. A question for the experts, I have a hash plate with about 10 creatures that look very similar to this. It is in my pile of unidentified fossils so I do not currently have a picture to post. It is stream worn but it has inflated bodies and arms coming out of it again as shown here. Do similar types of organisms exist in the Ordovician of SE Minnesota? I will probably have to post a pic but just curious for now

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