snakebite6769 Posted September 12, 2013 Share Posted September 12, 2013 Is it common to find Devonian aged fossils in conceetions, or are concretions from a certain time period like the mazon creek concretions which are Pennsylvanian? Link to comment Share on other sites More sharing options...
Fossildude19 Posted September 12, 2013 Share Posted September 12, 2013 Rob, I don't know if it is "common." I have found devonian trilobites in concretions at 18 Mile creek, and at a few other creeks in that general area. Sometimes, the nodules are really large with only one or two trilobites in them. One time I found a nodule that had 3 very tiny trilobites in them. In the gray Devonian shales and limestones of western NY, the concretions are usually a lighter color of gray than the surrounding rocks. This is my first decent trilobite I ever found, it was in a concretion I found lying in a creek. I think in Bolivia or one of the other South American countries,there is an area where they find many trilobites in nodules Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 IPFOTM -- MAY - 2024 _________________________________________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Jersey Posted September 12, 2013 Share Posted September 12, 2013 That's a really nice specimen. Is it a Phacops? Link to comment Share on other sites More sharing options...
Fossildude19 Posted September 12, 2013 Share Posted September 12, 2013 That's a really nice specimen. Is it a Phacops? Yes, although, technically it is now Eldredgeops. This was found in western NY. near Buffalo. Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 IPFOTM -- MAY - 2024 _________________________________________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
William Posted September 12, 2013 Share Posted September 12, 2013 Rob, I don't know if it is "common." I have found devonian trilobites in concretions at 18 Mile creek, and at a few other creeks in that general area. Sometimes, the nodules are really large with only one or two trilobites in them. One time I found a nodule that had 3 very tiny trilobites in them. In the gray Devonian shales and limestones of western NY, the concretions are usually a lighter color of gray than the surrounding rocks. This is my first decent trilobite I ever found, it was in a concretion I found lying in a creek. gallery_2806_718_19947.jpg I think in Bolivia or one of the other South American countries,there is an area where they find many trilobites in nodules Regards, That is really nice looking. Link to comment Share on other sites More sharing options...
William Posted September 12, 2013 Share Posted September 12, 2013 Rob, I don't know if it is "common." I have found devonian trilobites in concretions at 18 Mile creek, and at a few other creeks in that general area. Sometimes, the nodules are really large with only one or two trilobites in them. One time I found a nodule that had 3 very tiny trilobites in them. In the gray Devonian shales and limestones of western NY, the concretions are usually a lighter color of gray than the surrounding rocks. This is my first decent trilobite I ever found, it was in a concretion I found lying in a creek. gallery_2806_718_19947.jpg I think in Bolivia or one of the other South American countries,there is an area where they find many trilobites in nodules Regards, Tim, How did you open the concretion? Link to comment Share on other sites More sharing options...
Fossildude19 Posted September 12, 2013 Share Posted September 12, 2013 Tim, How did you open the concretion? Thanks, William. There were a few thoracic segments showing through the rock, and using that as my guide, (it was obviously an enrolled specimen.) I broke the nodule apart with hammer and chisel. Most of it came out of the nodule OK, but I did break a bit off ot the thorax, which needed to be glued onto the trilo. It is possible to break these concretions with a hammer and chisel, and I did it that way because I lacked experience in the matter. I think going forward, I would use the freeze/thaw method instead. Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 IPFOTM -- MAY - 2024 _________________________________________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
snakebite6769 Posted September 12, 2013 Author Share Posted September 12, 2013 Well the ones I have encountered are in Pennsylvania, not sure what formation, just know the area is Devonian. from what I can see its a greenops. Link to comment Share on other sites More sharing options...
Fossildude19 Posted September 12, 2013 Share Posted September 12, 2013 Well the ones I have encountered are in Pennsylvania, not sure what formation, just know the area is Devonian.image.jpg from what I can see its a greenops. Nice one, Rob. Can we get a "topside" view of it, looking down on the specimen? Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 IPFOTM -- MAY - 2024 _________________________________________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
piranha Posted September 12, 2013 Share Posted September 12, 2013 Excellent Greenops... is the right side preserved as well? Link to comment Share on other sites More sharing options...
snakebite6769 Posted September 12, 2013 Author Share Posted September 12, 2013 Yes, I am actually entering it in the FOTM contest, I almost yelled out loud when I found it. Hence my asking about Trilos in concretions I found a few of them at this location. I will post more detailed pics in the FOTM area. Just wanted a verification of what I found. I believe it is greenops. You can see where the extended cheeks went back into the concretion. I also found a baby trilo in a concretion. Link to comment Share on other sites More sharing options...
piranha Posted September 12, 2013 Share Posted September 12, 2013 Another key feature present for Greenops is the array of pygidial spines. Link to comment Share on other sites More sharing options...
snakebite6769 Posted September 12, 2013 Author Share Posted September 12, 2013 Those pictures are from my phone so they don't do her justice. Link to comment Share on other sites More sharing options...
Herb Posted September 12, 2013 Share Posted September 12, 2013 I have found Silurian trilos in concretions. "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
FossilDAWG Posted September 12, 2013 Share Posted September 12, 2013 Very cool trilobite. I'll have to look up the difference between Greenops and Bellcartwrightia when I get home, they are very similar but there are subtle differences in the glabellar furrows and in the spines on the pygydium. Concretions are associated with conditions that existed in the sediment at the time they formed, so they can be found in any time period. Basically some solute, usually calcium carbonate but sometimes other molecules such as silica, have to be dissolved in the wet sediment at close to the saturation point. Then, changes in the local chemistry, such as depletion of oxygen from the sediment by decay of organic material, can change the capacity of the water/sediment to dissolve the solute, so that it precipitates out and in the process cements the sediment particles into a hard concretion. What is very useful about the process is that it happens while the sediment is still saturated with water, before the sediment is buried so deeply the water gets squeezed out and the sediment is compressed into rock. That means fossils in the concretions are often fully 3-dimensional, unlike immediately adjacent fossils that were not captured inside developing concretions and so are often highly flattened, I have fossils in concretions from the Cambrian, Ordovician, Devonian, Pennsylvanian, Jurassic, Cretaceous, Oligocene, and Miocene. Don 2 Link to comment Share on other sites More sharing options...
MarleysGh0st Posted September 12, 2013 Share Posted September 12, 2013 There was a paper about Devonian concretions in a recent edition of Palaios: Wilson and Brett, “Concretions as Sources of Exceptional Preservation, and Decay as a Source of Concretions: Examples from the Middle Devonian of New York.” (The full article is behind a paywall, but your local university library may provide access.) The authors used CT scans of the concretions to discover pyritized trace fossils (and one brachiopod) inside them. These fossils may have served as the "seed" of the chemical reactions that created these concretions. Link to comment Share on other sites More sharing options...
AncientEarth Posted September 16, 2013 Share Posted September 16, 2013 In my collection, I have trilobites in concretions from Morocco, Bolivia, and the Czech Republic, a wide span in time for all these fossils as FossilDAWG made known. The specimens I have are from Silurian, Devonian, and Ordovician Periods. Link to comment Share on other sites More sharing options...
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