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minnbuckeye

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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. 

  

DSC_1266-002.thumb.JPG.e360a86e4dde6798b13cdc799b987c21.JPG

 

 2020-10-014.thumb.jpg.1a6cdb11cff5470a53a69950189ab389.jpg

 

 

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Are you sure it's not a nautiloid/goniatite?

Looks a bit like Phragmolites, to me. :unsure:  

 

@minnbuckeye

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    Tim    -  VETERAN SHALE SPLITTER

   MOTM.png.61350469b02f439fd4d5d77c2c69da85.png      PaleoPartner.png.30c01982e09b0cc0b7d9d6a7a21f56c6.png.a600039856933851eeea617ca3f2d15f.png     Postmaster1.jpg.900efa599049929531fa81981f028e24.jpg    VFOTM.png.f1b09c78bf88298b009b0da14ef44cf0.png  VFOTM  --- APRIL - 2015  

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"In every walk with nature one receives far more than he seeks."

John Muir ~ ~ ~ ~   ><))))( *>  About Me      

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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

   MOTM.png.61350469b02f439fd4d5d77c2c69da85.png      PaleoPartner.png.30c01982e09b0cc0b7d9d6a7a21f56c6.png.a600039856933851eeea617ca3f2d15f.png     Postmaster1.jpg.900efa599049929531fa81981f028e24.jpg    VFOTM.png.f1b09c78bf88298b009b0da14ef44cf0.png  VFOTM  --- APRIL - 2015  

__________________________________________________
"In every walk with nature one receives far more than he seeks."

John Muir ~ ~ ~ ~   ><))))( *>  About Me      

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@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

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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

image.png.ffc9af9069a5919fcec096095cfcda87.png  Note the triangular shape in 22 (hence the name)

 

image.png.c56949fdf4b5f426e5b7407134581dd5.png

 

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.  

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4 hours ago, ClearLake said:

I'd go with Phragmolites obliquus

That is my best assumption

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  • 3 months later...

Cyrolites retrorsus pretty much decorah only. Rather tiny, uncommon to me. In many ways it can be mistaken for phragomites. 

 

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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. 

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