Tales From the Shale Posted September 1, 2022 Share Posted September 1, 2022 State: Iowa Location: Graf Period: Ordovician Cruised over to Iowa for the first time in years last weekend. I went to observe and scout the famous cephalopod beds in Graf. I have to say, it was everything I had hoped it would be. The wall in which the RC was located upon, was a few hundred meters in length, and contained a few layers, dominated by dolostone, limestone and towards the bottom, phosphatic shales. I ended up finding graptolites too, which I wanted to say were Orthograptus? However I didn't bother to keep any. These were most of my finds, minus the plates I took home as well. Here was the largest hashplate, I feel like slapping this one on my desk due to the sheer chaos it exudes. Here was an unexpected find in the form of three fragmentary trilobite pygidiums. I wasn't aware they could be found here, so I'm unsure of the taxa designation. The funniest about these was I found them all within five minutes of each other. 10/10 would gif gaf up in Graf again. Next time though, I want to see if I can locate some supposed Isotelus fragment beds up near Elgin. 8 Link to comment Share on other sites More sharing options...
connorp Posted September 1, 2022 Share Posted September 1, 2022 The trilobite species is Thelecalymene mammillata. Bits are fairly common but I've never seen anything articulated. 2 Link to comment Share on other sites More sharing options...
piranha Posted September 1, 2022 Share Posted September 1, 2022 These trilobite pygidia are typically found associated in the Isorthoceras beds: Thelecalymene mammillata Whittington, H.B. 1971 A New Calymenid Trilobite from the Maquoketa Shale, Iowa. Smithsonian Contributions to Paleobiology, 3:129-136 PDF LINK Witzke, B.J., Glenister, B.F. 1987 Upper Ordovician Maquoketa Formation in the Graf Area, Eastern Iowa. North-Central Section of the Geological Society of America, Centennial Field Guide, 3:103-108 2 Link to comment Share on other sites More sharing options...
Nimravis Posted September 2, 2022 Share Posted September 2, 2022 Nice finds. It is a cool location to collect, though parking on that narrow road is a challenge as it the undercutting of the wall. I hit that site on the way home from the MAPS Fossil show a few years back. I collected a lot of material on that visit. Link to comment Share on other sites More sharing options...
Manticocerasman Posted September 2, 2022 Share Posted September 2, 2022 I love all those orthocones 1 growing old is mandatory but growing up is optional. Link to comment Share on other sites More sharing options...
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