crinus Posted March 5, 2018 Share Posted March 5, 2018 This specimen recently came into my possession with the information given below. I have googled the information and come up with nothing about the trilobite. I believe the location information is correct as I did find some information on the Brandon Bridge Fm. and it does describe the matrix correctly. I also remember reading about this trilobite or something similar on this forum a while back but cannot find the topic. I would appreciate help with the ID of this trilobite. I am pretty sure it is quite rare and would love to add it to my collection. Dalmanitae sp. Brandon Bridge Fm., Joilet Group L. Silurian Waukaisa Co., Wisconsin This is all that came with the specimen. Joe 2 Link to comment Share on other sites More sharing options...
doushantuo Posted March 5, 2018 Share Posted March 5, 2018 I WILL be shot down for this,but any chance of it being Ommokris?* *I'm aware(I think) of the nomenclatural difficulties(vide,e.g.Ramskold,Jell & Adrain) Link to comment Share on other sites More sharing options...
JohnBrewer Posted March 5, 2018 Share Posted March 5, 2018 @piranha John Map of UK fossil sites Link to comment Share on other sites More sharing options...
piranha Posted March 5, 2018 Share Posted March 5, 2018 Last I heard, the Brandon Bridge dalmanitid remains undescribed. I will check with a colleague to see if there is any updated info. Here are a couple of examples from my image library. The one on the right is from fossilcrazy, but I could not find his original post. Mikulic, D.G., Briggs, D.E.G., & Kluessendorf, J. (1985) A new exceptionally preserved biota from the Lower Silurian of Wisconsin, U.S.A. Philosophical Transactions of the Royal Society of London B, 311:75-85 2 Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted March 5, 2018 Share Posted March 5, 2018 I think this may be the one? : Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
piranha Posted March 5, 2018 Share Posted March 5, 2018 That is the same trilobite, but it must have been a different post. The image file I used is larger and does not have the text at the bottom. Link to comment Share on other sites More sharing options...
piranha Posted March 5, 2018 Share Posted March 5, 2018 Sorry to report there is no update on this dalmanitid. In the photo that Tidgy's Dad linked above, it is labeled Odontochile sp., as a few others have also labeled these trilobites over the years. Typically Odontochile should have more pygidial ribs and axial rings. Because of the large eyes, long genal spines, and distinctive pygidial notch, there is a good possibility it would eventually be described as a new genus. Until these Waukesha County dalmanitds get a formal description, I would label it: Dalmanitidae sp. 3 Link to comment Share on other sites More sharing options...
DevonianDigger Posted March 5, 2018 Share Posted March 5, 2018 @crinus Jay A. Wollin Lead Fossil Educator - Penn Dixie Fossil Park and Nature Reserve Hamburg, New York, USA Link to comment Share on other sites More sharing options...
RJB Posted March 5, 2018 Share Posted March 5, 2018 Nice lookin bug for sure! RB Link to comment Share on other sites More sharing options...
Haravex Posted March 5, 2018 Share Posted March 5, 2018 I don't even collect or like trilobites that much but that sure is a nice one Link to comment Share on other sites More sharing options...
piranha Posted March 6, 2018 Share Posted March 6, 2018 Additional info from a colleague specializing in Silurian dalmanitids. After further review we still remain: Dalmanitidae sp. yet to be determined Many thanks for your email with the photo of the interesting dalmanitid. You are correct that forms generally assigned to Odontochile have pygidia with a larger number of segments and a posterior spine rather than an embayment, so your species cannot be accommodated in that genus, which is currently applied to species from the Lower Devonian. The embayment is of course the most distinctive feature of the species; the other characters you mention (large eyes, long genal spines), while characteristic (I would also add the very wide pygidial doublure, as indicated by the paradoublural line), are found also in some other dalmanitids. Only a few dalmanitids with a posterior pygidial embayment are known, mostly from the Lower to Middle Devonian, mostly belonging to the Synphoriinae rather than the Dalmanitinae, and so not at all closely related to your species. Apart from your species, I know of only one dalmanitid pygidium with an embayment from the Silurian, and it is of similar age to yours (late Llandovery). It was assigned by Curtis & Lane (1998, Llandovery trilobites of England and Wales, Part 2. Palaeontographical Society Monograph, pl. 8, fig. 2) to the type species of their new genus Bessazoon. It has a greater number of segments, and the doublure is perhaps not quite as wide. However, there are problems with Bessazoon, as the specimens assigned to the type species by Curtis & Lane seem to belong to more than one species (they also included pygidia with a posterior spine). I regard the genus as unusable as its identity is unclear, so I don’t think it can be applied to your species with any degree of confidence. 3 Link to comment Share on other sites More sharing options...
crinus Posted March 6, 2018 Author Share Posted March 6, 2018 Thank you all for this response. It is very much appreciated. And it is good to know that I was not dreaming regarding that I saw something about this trilobite on this site. I may be old but my brain is still intact. I will label it as piranha indicated with the correct spelling of the county. Joe 1 Link to comment Share on other sites More sharing options...
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