Fossildude19 Posted June 4, 2011 Share Posted June 4, 2011 (edited) I've had this on my shelf for a number of years now, and have finally decided to ask for an ID. It was found in a river cobble in Herkimer NY, along the river that runs alongside Rte. 28. The area is mostly Ordovician, but,... like I said, this was found in float from a river bed. Unfortunately there is damage to the cephalon - which complicates matters. I was thinking Radnoria,...but would like some other opinions. The specimen is roughly 8mm long by 6.5 mm wide. Thanks in advance for any help. Regards, Edited June 4, 2011 by Fossildude19 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "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...
FrozenInTime Posted June 4, 2011 Share Posted June 4, 2011 Really difficult item Tim, seeing as the size suggests it is a meraspid. I count 6 thoracic segments on your specimen, and this would acknowledge my suspicion as pretty much all adult proetids I know from your state have at least 9. It could also very well be a meraspid of one of the following Ordovician genera: Bathyurus, Raymondites, or a Devonian Dechenella? The crystalline matrix it is in may be able to help you get closer to solve this mystery? I don't think that it is typical for the Silurian in your area, or is it? Good luck! cheers, Mark 1 Link to comment Share on other sites More sharing options...
Fossildude19 Posted June 4, 2011 Author Share Posted June 4, 2011 Really difficult item Tim, seeing as the size suggests it is a meraspid. I count 6 thoracic segments on your specimen, and this would acknowledge my suspicion as pretty much all adult proetids I know from your state have at least 9. It could also very well be a meraspid of one of the following Ordovician genera: Bathyurus, Raymondites, or a Devonian Dechenella? The crystalline matrix it is in may be able to help you get closer to solve this mystery? I don't think that it is typical for the Silurian in your area, or is it? Good luck! cheers, Mark Mark, Thanks for your reply. I'm not real familiar with the rocks of that area - the matrix around this piece is a very hard/chert - like type of rock. Most of the rock in the area is a typical Ordovician black shale. I will check the other species you mention. Thanks again! Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "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...
Fossildude19 Posted June 4, 2011 Author Share Posted June 4, 2011 (edited) More pics. Edited June 4, 2011 by Fossildude19 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "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...
FrozenInTime Posted June 4, 2011 Share Posted June 4, 2011 Hmm, upon closer inspection: The amount of axial rings on the pygidium actually rules out any Bathyuroidea. The smooth exoskeleton rules out Radnoria. I think I would stick to a representative of the genus Dechenella, which would make it Devonian. I must add that the preservation looks so exceptional you may want to spend time tracking down the parent strata. cheers, Mark 1 Link to comment Share on other sites More sharing options...
Fossildude19 Posted June 4, 2011 Author Share Posted June 4, 2011 Mark. Unfortunately, this was found over 10 years ago, and the site is about 3-4 hour drive from my home. I may have to check the area again, sometime in the future. I appreciate your efforts. Thanks again. Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "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...
Caleb Posted June 4, 2011 Share Posted June 4, 2011 (edited) I'm gonna throw my hat into the ring of ideas and say I believe it may be a juvenile Isotelus. The hypostome is visible where the glabella is missing and it's looking very Isotelus-ish. Here is a growth series of Isotelus gigas based on Raymond, 1941. Edited June 4, 2011 by Caleb 1 Caleb Midwestpaleo.com Link to comment Share on other sites More sharing options...
piranha Posted June 4, 2011 Share Posted June 4, 2011 Caleb is correct as this is certainly an isoteline trilobite. This individual exhibits six segments as a meraspid that had not yet fully released all of its thoracic tergites yet. For comparison one would expect a size of approximately 3mm for an isotelid meraspid with only one segment released (M1). Figured drawings appear to suggest a more defined 3D pygidial axis in I.gigas that would have become lost by the holaspid stage of development. If the lower Ordovician of New York is a possibility then Isoteloides canalis has a distinctive pygidial axis that warrants consideration as well. 1 Link to comment Share on other sites More sharing options...
Fossildude19 Posted June 4, 2011 Author Share Posted June 4, 2011 I'm gonna throw my hat into the ring of ideas and say I believe it may be a juvenile Isotelus. The hypostome is visible where the glabella is missing and it's looking very Isotelus-ish. Here is a growth series of Isotelus gigas based on Raymond, 1941. Caleb, Wow - I never would have thought of that!!! Thanks for your insights! That 1st picture in the series certainly looks very close! Thanks so much for your answer! Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "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...
Fossildude19 Posted June 4, 2011 Author Share Posted June 4, 2011 Caleb is correct as this is certainly an isoteline trilobite. This individual exhibits six segments as a meraspid that had not yet fully released all of its thoracic tergites yet. For comparison one would expect a size of approximately 3mm for an isotelid meraspid with only one segment released (M1). Figured drawings appear to suggest a more defined 3D pygidial axis in I.gigas that would have become lost by the holaspid stage of development. If the lower Ordovician of New York is a possibility then Isoteloides canalis has a distinctive pygidial axis that warrants consideration as well. Scott, Thanks for your efforts. I appreciate all the info. I'm a total amateur when it comes to Trilobites. I have a bit of home work to do, it would seem. Thanks again - it's very appreciated! Regards, Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "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...
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