Wrangellian Posted January 10, 2013 Share Posted January 10, 2013 Got this from ebay recently but it was not ID'd with any certainty - anyone know their Mazon stuff and have a suggestion? The seller's blurb included this: The half siderite concretion that is 3 1/4 inches across appears to have a jellyfish but its identification is in doubt. It's probably a buddy of Reticulomedusa greenei (Phylum Cnidaria, Class Scyphozoa). According to page 5 of the 202 page book The Mazon Creek Fossil Fauna by J. Wittry, 2012, "Specimens similar can only be doubtfully referred to as R. greenei. These forms have the correct overall appearance, but lack the reticulated pattern needed to make identification a certainty." The specimen has a one inch long elevated region with a curved end. About half the animal has a ridge extending around its margin. There are also some small bumps. I can see a thin, precise margin around it near the edge of the concretion that I wonder if it's part of the organism or just a flow/seepage pattern(?) though it only goes about halfway around. Maybe it's just my imagination but I can picture short tentacles or 'hairs' around this margin reaching to the edge of the rock. The two depressions on either side of the inner ridge are also intriguing, seem to imply something more firm than the rest of the body. And is that bump in the middle the oral/anal cavity? Link to comment Share on other sites More sharing options...
glacialerratic Posted January 10, 2013 Share Posted January 10, 2013 I'd say that's a decent ID. Nice acquisition! Link to comment Share on other sites More sharing options...
Shamalama Posted January 10, 2013 Share Posted January 10, 2013 If that is indeed a jellyfish then you have a nice specimen. I've always been doubtful about any fossils labelled as such and posted for sale. It seems to me that any random blobby looking thing from Mazon Creek is labelled as a Jellyfish. -Dave __________________________________________________ Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPheeIf I'm going to drive safely, I can't do geology. - John McPheeCheck out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/ Link to comment Share on other sites More sharing options...
Wrangellian Posted January 10, 2013 Author Share Posted January 10, 2013 (edited) I know, but the price was right. I knew it looked different from the other Mazon jellyfish I have (E. asherae) and had enough features I thought it had a chance of being ID'd. I really wanted the Hydrozoan the same seller had but it went a little high for my budget! (maybe someone still got a deal on it) Thanks guys... so it is tentatively a 'buddy of Reticulomedusa greenei'... Can anyone show me a reconstruction of R. greenei? I don't have any of the Mazon guidebooks. I'm curious if the mental image I have of this thing is at all accurate. Edited January 10, 2013 by Wrangellian Link to comment Share on other sites More sharing options...
Crinoid Queen Posted January 11, 2013 Share Posted January 11, 2013 I hope it is a jellyfish. I don't see it either? Do you go to any larger fossils shows? I would take it to some one with stuff from Mazon and see if they could give you a better ID they just the phylum. Some one that knows the area's fossils intimately can usually just rattly off the name with a second's glance. My final crinoid ID help is at MAPS lol -CQ Link to comment Share on other sites More sharing options...
RCFossils Posted January 11, 2013 Share Posted January 11, 2013 Well, I can tell you it is definately a jellyfish. The preservation makes it difficult to say for certain but in my opinion, it appears to be an Esexella asherae. If you do a search, i did a post on Mazon jellyfish. I will attach a few pictures of a Reticulomedusa greenei. Link to comment Share on other sites More sharing options...
Wrangellian Posted January 11, 2013 Author Share Posted January 11, 2013 Any sufficiently large fossil show is probably too far away from me to attend much as I'd like to, but thanks CQ! OK I'll check out your jellyfish post RCF. If this is E. asherae, why does it look so different from the others I have/have seen - is it a different orientation? I guess these things take a while to learn to interpret - like an Aborigine giving you an animal's CV just by its tracks. Link to comment Share on other sites More sharing options...
RCFossils Posted January 11, 2013 Share Posted January 11, 2013 Any sufficiently large fossil show is probably too far away from me to attend much as I'd like to, but thanks CQ! OK I'll check out your jellyfish post RCF. If this is E. asherae, why does it look so different from the others I have/have seen - is it a different orientation? I guess these things take a while to learn to interpret - like an Aborigine giving you an animal's CV just by its tracks. Specimens of E asherae are highly variable. This is partly due to the fact it is not much more then a bag of water and you are correct that specimens can look very different based on the orientation of the animal. Another factor is how much decay took place prior to burial. It is also possible that some of the jellies we call E. asherae could represent multiple undescribed species. Link to comment Share on other sites More sharing options...
Wrangellian Posted January 11, 2013 Author Share Posted January 11, 2013 (edited) OK, this one does look different for whatever reason and I'm glad to have it because of that. BTW Can you see the thin margin that goes about halfway around near the outside edge of the rock? Is this part of the jelly and if so, does it have small 'tentacles' coming off it or is that just my imagination? (not much room to see them in that narrow band between the line and the edge of concretion) - it looks like overlapping fine tentacles or hairs. Edited January 11, 2013 by Wrangellian Link to comment Share on other sites More sharing options...
Terry Dactyll Posted January 12, 2013 Share Posted January 12, 2013 Great aquisition.... Very unusual material.... Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
glacialerratic Posted January 12, 2013 Share Posted January 12, 2013 I think that is just the edge of the nodule. Link to comment Share on other sites More sharing options...
Wrangellian Posted January 13, 2013 Author Share Posted January 13, 2013 Oh well, thanks Tim. Link to comment Share on other sites More sharing options...
RCFossils Posted January 13, 2013 Share Posted January 13, 2013 Yes, what you are looking at is not part of the fossil. Link to comment Share on other sites More sharing options...
Wrangellian Posted January 13, 2013 Author Share Posted January 13, 2013 It just looks like such a distinct line like the edge of any other soft-bodied fossil, I had to wonder, but I also wondered why it only went halfway around. I guess it is some kind of boundary perhaps around the part of the rock affected by seepage out of the dead jelly? I have seen similar features around organic bits in my local shale. Link to comment Share on other sites More sharing options...
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