minnbuckeye Posted October 13, 2020 Share Posted October 13, 2020 I had to make a trip to the "big" city of Rochester, Mn today. As I drove by a new building site that exposed some Decorah Shale, I had to make a stop. The Decorah Shale is an impervious layer that keeps pollution from seeping into deeper rock layers and contaminating our ground water. Obviously, building permits are being obtained without adherence to the zoning which prevents interuption of this great geologic feature! I will drink my own water but collect fossils from these ill conceived sites. While visiting such a site, I discovered this tiny gastropod that I can not identify. 1 Link to comment Share on other sites More sharing options...
Fossildude19 Posted October 13, 2020 Share Posted October 13, 2020 Are you sure it's not a nautiloid/goniatite? Looks a bit like Phragmolites, to me. @minnbuckeye 3 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...
minnbuckeye Posted October 13, 2020 Author Share Posted October 13, 2020 @Fossildude19, you hit the nail on the head!!!!! Thanks Link to comment Share on other sites More sharing options...
Fossildude19 Posted October 13, 2020 Share Posted October 13, 2020 59 minutes ago, minnbuckeye said: @Fossildude19, you hit the nail on the head!!!!! Thanks Glad to help. But, just so you know, it is a gastropod, (Bellerophont) not an ammonoid as I initially stated. 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...
minnbuckeye Posted October 13, 2020 Author Share Posted October 13, 2020 @Fossildude19, I didn't want to question that even though I knew Bellerophonts are gastropods. Just glad for an ID. I tried to narrow it to genus and species. It looks like P triangularis but this occurs in the Platteville. It also is close to P obliquus which does occur in the Decorah, but is stated NOT to be found in our area. Any thoughts????? Mike Link to comment Share on other sites More sharing options...
ClearLake Posted October 14, 2020 Share Posted October 14, 2020 Mike If you really think it is one of those two species, here are some drawings out of Ulrich, E. O., and W. H. Scofield. 1897. The Lower Silurian Gastropoda of Minnesota where they were both described. First one is P. triangularis and second it P. obliquus Note the triangular shape in 22 (hence the name) If it were just a choice between those two (I have not looked at any other options), I'd go with Phragmolites obliquus. And since it is found in the Decorah, that seems logical. Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 14, 2020 Author Share Posted October 14, 2020 4 hours ago, ClearLake said: I'd go with Phragmolites obliquus That is my best assumption Link to comment Share on other sites More sharing options...
Tetradium Posted January 27, 2021 Share Posted January 27, 2021 Cyrolites retrorsus pretty much decorah only. Rather tiny, uncommon to me. In many ways it can be mistaken for phragomites. Link to comment Share on other sites More sharing options...
Tetradium Posted January 27, 2021 Share Posted January 27, 2021 By the way I hadnt heard of any lower silurian exposures in Minnesota lol. Suppose to be missed with Devorian in farther south east buried deeply. Link to comment Share on other sites More sharing options...
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