MarcusFossils Posted July 1, 2017 Share Posted July 1, 2017 Hi all, I received this 2cm trilobite as a gift from a friend, who claims its from the Grass Valley, Lander County, Nevada. After a bit of reading, I'm fairly confident this means Nevada Limestone Formation. I can however only find references to Phacops, Proetus, Dalmanites and Phillipsia from this Formation..is this a Proetus sp? Help appreciated Marc Website: https://www.instagram.com/paleo_archives/ --------------------------------------------------------------------------- “It is by no means an irrational fancy that, in a future existence, we shall look upon what we think our present existence, as a dream.” ― Edgar Allan Poe Link to comment Share on other sites More sharing options...
piranha Posted July 1, 2017 Share Posted July 1, 2017 1 hour ago, MarcusFossils said: I received this 2cm trilobite as a gift from a friend, who claims its from the Grass Valley, Eureka County, Nevada. After a bit of reading, I'm fairly confident this means Nevada Limestone Formation. I can however only find references to Phacops, Proetus, Dalmanites and Phillipsia from this Formation..is this a Proetus sp? Phillipsiids occurred in the Carboniferous-Permian, certainly not with any dalmanitids or phacopids. What paper had this info? Link to comment Share on other sites More sharing options...
MarcusFossils Posted July 1, 2017 Author Share Posted July 1, 2017 15 minutes ago, piranha said: Phillipsiids occurred in the Carboniferous-Permian, certainly not with any dalmanitids or phacopids. What paper had this info? Found this is a Google book, here's the relevant information: Title Paleontology of the Eureka DistrictVolume 8 of Monographs of the United States Geological Survey Author Charles Doolittle Walcott Publisher U.S. Government Printing Office, 1884 Website: https://www.instagram.com/paleo_archives/ --------------------------------------------------------------------------- “It is by no means an irrational fancy that, in a future existence, we shall look upon what we think our present existence, as a dream.” ― Edgar Allan Poe Link to comment Share on other sites More sharing options...
piranha Posted July 1, 2017 Share Posted July 1, 2017 Remember to check more carefully when using the older literature. There are a lot of updates since Walcott's work from the late 1800's. Walcott wasn't sure if it was Phillipsia? or Brachymetopus?, and Phillipsia and Brachymetopus do not occur in the Devonian of North America, so we would have to cross-reference Hall's figures to try and and make a better determination. In any event, Walcott only had a glabella, so that one really is a wild goose chase. The "Phacops" in the report is probably Viaphacops claviger from the Lower Devonian Wenban Limestome in Eureka County. Back to the mystery trilobite: Take some sharply focused photos without angles. Top-down, lateral-side and a close-up of the cephalon, hopefully some more details will be revealed. Link to comment Share on other sites More sharing options...
MarcusFossils Posted July 1, 2017 Author Share Posted July 1, 2017 10 minutes ago, piranha said: Back to the mystery trilobite: Take some sharply focused photos without angles. Top-down, lateral-side and a close-up of the cephalon, hopefully some more details will be revealed. Website: https://www.instagram.com/paleo_archives/ --------------------------------------------------------------------------- “It is by no means an irrational fancy that, in a future existence, we shall look upon what we think our present existence, as a dream.” ― Edgar Allan Poe Link to comment Share on other sites More sharing options...
MarcusFossils Posted July 1, 2017 Author Share Posted July 1, 2017 Thanks for the help Scott! Here's a later shot: Website: https://www.instagram.com/paleo_archives/ --------------------------------------------------------------------------- “It is by no means an irrational fancy that, in a future existence, we shall look upon what we think our present existence, as a dream.” ― Edgar Allan Poe Link to comment Share on other sites More sharing options...
piranha Posted July 1, 2017 Share Posted July 1, 2017 The key feature on this trilobite is the prominent glabellar lobe. After some color enhancement, I showed the photos to a colleague, and we agree the trilobite is an aulacopleurid. There are a several species described from the Wenban Limestone in Adrain 2009, and Maurotarion periergum appears to be the best match. As an added bonus, the paper also solves the mystery of Walcott's Phillipsia? Brachymetopus? riddle as: Mystrocephala sp. Adrain, J.M. (2009) New and revised species of the aulacopleurid trilobite Maurotarion from the Lower Devonian (Pragian) of Nevada. Zootaxa, 2215:1-23 PDF LINK Link to comment Share on other sites More sharing options...
MarcusFossils Posted July 1, 2017 Author Share Posted July 1, 2017 2 minutes ago, piranha said: The key feature on this trilobite is the prominent glabellar lobe. After some color enhancement, I showed the photos to a colleague, and we agree the trilobite is an aulacopleurid. There are a several species described from the Wenban Limestone in Adrain 2009, and Maurotarion periergum appears to be the best match. As an added bonus, the paper also solves the mystery of Walcott's Phillipsia? Brachymetopus? riddle as: Mystrocephala sp. Adrain, J.M. (2009) New and revised species of the aulacopleurid trilobite Maurotarion from the Lower Devonian (Pragian) of Nevada. Zootaxa, 2215:1-23 PDF LINK Your amazing! Thanks Scott Website: https://www.instagram.com/paleo_archives/ --------------------------------------------------------------------------- “It is by no means an irrational fancy that, in a future existence, we shall look upon what we think our present existence, as a dream.” ― Edgar Allan Poe Link to comment Share on other sites More sharing options...
doushantuo Posted July 1, 2017 Share Posted July 1, 2017 Scott,I downloaded that one just this morning,because of this thread Zt is pretty good, graphically speaking. Link to comment Share on other sites More sharing options...
MarcusFossils Posted July 1, 2017 Author Share Posted July 1, 2017 24 minutes ago, piranha said: There are a several species described from the Wenban Limestone in Adrain 2009, and Maurotarion periergum appears to be the best match. I'm curious though, why M. periergum and not M. wenbanense? The axial spine seems much less wide on my specimen than on M. periergum, more in line with M. wenbanense. Website: https://www.instagram.com/paleo_archives/ --------------------------------------------------------------------------- “It is by no means an irrational fancy that, in a future existence, we shall look upon what we think our present existence, as a dream.” ― Edgar Allan Poe Link to comment Share on other sites More sharing options...
piranha Posted July 1, 2017 Share Posted July 1, 2017 22 minutes ago, MarcusFossils said: I'm curious though, why M. periergum and not M. wenbanense? The axial spine seems much less wide on my specimen than on M. periergum, more in line with M. wenbanense. Just a slight amount of lateral compression would make the axial lobe appear to be narrower. Also, Maurotarion wenbanense has prominent axial tubercles, Maurotarion periergum does not. Link to comment Share on other sites More sharing options...
doushantuo Posted July 1, 2017 Share Posted July 1, 2017 Scott,i take it you mean some slight tectonic deformation has taken place? Link to comment Share on other sites More sharing options...
piranha Posted July 1, 2017 Share Posted July 1, 2017 11 minutes ago, doushantuo said: Scott,i take it you mean some slight tectonic deformation has taken place? The paper does mention flattened, coarsely silicified trilobites, somewhat tectonically deformed. However, it appears this specimen essentially preserves its original dimensions with a slight amount of lateral compression, probably by contemporaneous post-mortem compaction of sediment. Because only the left peural lobe is slightly folded, tectonic deformation seems unlikely for the posted specimen. Link to comment Share on other sites More sharing options...
doushantuo Posted July 2, 2017 Share Posted July 2, 2017 OK Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.