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Decorah Shale, heavy on Brachiopods


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@piranha  This is the screenshot I saw when I followed the link and why I thought it was authored by Sloan.  :-)5e8faaea601e3_pdfsloan.png.b10bb6c39dc1ff7f59f4d4c985c0ca8f.png

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minnbuckeye
2 hours ago, Tidgy's Dad said:

without a scale in the pictures (ahem;))

 

I quickly threw these pics together and knew I would receive some chastising for not having a scale. I will answer your questions and put sizes with the pics. I knew I wouldn't need piranha's and Bev's suggestion cause I have ADAM!!!! In actuality, I appreciate all three of you making an attempt at solving my ID dilemma. 

 

 Mike

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Tidgy's Dad
1 hour ago, minnbuckeye said:

 

I quickly threw these pics together and knew I would receive some chastising for not having a scale. I will answer your questions and put sizes with the pics. I knew I wouldn't need piranha's and Bev's suggestion cause I have ADAM!!!! In actuality, I appreciate all three of you making an attempt at solving my ID dilemma. 

 

 Mike

Well, thanks, but I'm not actually sure I'm right. 

Just opening gambits for now..........;)

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41 minutes ago, Bev said:

@piranha  This is the screenshot I saw when I followed the link and why I thought it was authored by Sloan.  :-)

 

 

All you had to do was open the pdf to verify the citation I provided was correct ... maybe next time! :DOH::P

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minnbuckeye
3 hours ago, Tidgy's Dad said:

without a scale in the pictures (ahem;))

 

@Tidgy's Dad, I quickly threw these pics together and knew I would receive some chastising for not having a scale. I will answer your questions and put sizes with the pics. I knew I wouldn't need piranha's and Bev's suggestion cause I have ADAM!!!! In actuality, I appreciate all three of you making an attempt at solving my ID dilemma. My original pics now  show sizes, if that helps. Will take another picture of #2 tomorrow. Would other views of other brachs help? Just ask!

 

 Mike

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Tidgy's Dad

Okay, it's late here, so I'll just look at number one til tomorrow and the extra piccie.

The first one maybe your Pionodema subaequata as that species does usually have finer costellae, but not always, and due to the beak shape I'll stick with Doleroides pervetus for now. The size fits both species. They are the only two biconvex orthids in the Decorah, I think and are quite difficult to tell apart without seeing the internal structure.  

The one on the far right does look a bit like an atrypid, but isn't as no atrypid has an interarea or hinge line like that, your specimen has a delthyrium which appears to be open, again suggesting Doleroides, ( Pionodema has a plate in the delthyrium) I think this one is just morphologically rather different which is not at all unusual for brachiopods. 

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minnbuckeye

#2 as requested: 

 

 2019-06-005.thumb.jpg.0d728e4e7ae8a6270c4c7c9f258ae249.jpg

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18 hours ago, Tidgy's Dad said:

Yes, I already have the papers linked by Scott and they are invaluable. 

Anyway, without a scale in the pictures (ahem;)) it's a bit more tricky, but I think , maybe :

1 : Doleroides pervetus.

2. Pionodema subaequata is possible, but I think Dalmanella sculpta -  how big and can I see the commisure, please? 

3. That's not Zygospira, that's a rhynchonellid,  probably Rostricellula minnesotensis. How many costae? 

4. Is yummy. I think that's Strophomena filitexta? 

5. Seems to be Doleroides pervetus again.

6. Looks pretty small, so maybe Dinorthis pectinella.

7. Diorthelasma? But the dentition looks a bit off.

8. Rostricellula or Rhynchotrema. 

Some beautiful brachs................:wub:

Tony @Peat Burns, any ideas?  

I'm afraid I am not directly familiar with a number of those taxa nor that particular formation and would have to consult the literature.  I'll sit this one out :)

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Tidgy's Dad
5 hours ago, Peat Burns said:

I'm afraid I am not directly familiar with a number of those taxa nor that particular formation and would have to consult the literature.  I'll sit this one out :)

Thanks for looking.:)

I only know a bit about this formation because Mike and Lori @GeschWhat have both kindly sent me Decorah fossils so i did some research.

 

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Tidgy's Dad

Commisure looks pretty straight, so I'll stick with Dalmanella sculpta. 

3. Rostricellula minnesotensis has a maximum of 22, so this must be Rhynchotrema wisconsinense which can have 18 to 24. 

4. I concur that a sulcus would be unusual, but maybe that's damage or a pathology? 

I stick with the rest. 

The last two are rhynchonellids, Rostricellula minnesotnesis, Rhychotrema wisconsinense or Rhychotrema ainsliei, a count of the ribs would help. 

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Those are very attractive specimens. I especially appreciate the colors and certain details in the preservation. Great finds! Congratulations. 

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minnbuckeye

 @Tidgy's Dad       Thanks Adam!!  Now anyone exploring the Decorah Shale can have a jump start on their IDs, thanks to you. 

 

Mike

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  • 4 weeks later...
On 4/9/2020 at 6:49 PM, piranha said:

 

 

All you had to do was open the pdf to verify the citation I provided was correct ... maybe next time! :DOH::P

I'm not the sharpest knife in the drawer, you know.  :-)  Two strokes and old age get to a person...

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  • 9 months later...
Tetradium

#8 is orthid family not rhy family. Otherwise I hadn't heard of any experts disagreeing over Doleriodes pervetus labels. And yes Doleriodes pervetus looks a lot like spirifer brachiopods like atrypa.  Heck the only other similar and can be confused with is Pionodema subaequata but even pics online from other regions looks different as well too. The pionodema subaequata of this region is strongly rectangle shaped and the beak is smaller, almost even with base. 

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Tetradium

Most likely Hesperorthis tricenaria. I'm working on orthid brachiopods now after finding I really messed them up lol. They're like triangular version of cockle shells. 

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Tidgy's Dad
1 hour ago, Tetradium said:

 spirifer brachiopods like atrypa.  

Atrypa is an atrypid, not a spiriferid.

1 hour ago, Tetradium said:

Most likely Hesperorthis tricenaria. 

This is Hesperorthis tricenaria from the Platteville Formation, Grant County, Wisconsin 1.7 mm wide:

Hesperorthis1.thumb.jpg.dcfd45706260844a63780a7e4b09ce0f.jpg

Hesperorthis2.thumb.jpg.cc99b52c0e6084dc1ce73afab31ed436.jpg

Hesperorthis3.thumb.jpg.15079333e6e0e0eb0c1a007cbd3bb50c.jpg

Hesperorthis4.thumb.jpg.42c9cfbdb9e7793f87e64633d46b369f.jpg

20190101_020733-1.thumb.jpg.57c1ffc957c0186fe73802b79091f442.jpg

This one (bottom centre is from the Decorah Shale a little south of Decorah, Iowa.

1.thumb.jpg.da90f0ec6ee04a7155941eb978eb5dad.jpg

Hesperorthis6.thumb.jpg.f00a8eb7aada4c6dc6fd7fa04bab0d6c.jpg

Hesperorthis7.thumb.jpg.ee0b18aa5664edc9f6da0434103410f0.jpg

 

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Tetradium

Thats what I think #8 and #9 is.  The tiny complete one in lower middle I suspects is the devonian from rockford Iowa. Once in a while I get them mixed in by mistake. 

100_9015.JPG

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Tetradium

Heck I have a few that frustrates me. First one maybe a new species of Pionodema or Doleriodes? The weird thing is they all are pretty constant in size and are very inflated compared to Doleriodes pervetus while having that inconsistent line similar to some Pionodema subaequata. Second picture for a while was with the other regular rhy family and looks much like them until one day I found those 3 that had that transverse ridges like Lepidocyclus which hadnt been reported from Minnesota at all. Are they Lepidocyclus or somehow much better preserved than vast majority of their kind?   

100_9017.JPG

100_9000.JPG

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Tetradium

Not long after I posted the last two pics and took a short nap it popped in my mind that #1 could be Decorah version of Oepikina minnesotensis. From what I found from the Stroph family, at least for Minnesota I found a easier way to describe the different genus (except for rarer genus that I hadnt found yet. Strophomena is the most classic half moon shape of the family. Sowerbylus is like if you take a dough, shape it in a half moon then stretch from both sides. Rafinesquina is like if you take the dough shaped like half moon and stretch the circle part outward. Oepikina is like if you shape the half moon dough just like a regular shovel. 

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On 2/23/2021 at 7:44 PM, Tetradium said:

Thats what I think #8 and #9 is.  The tiny complete one in lower middle I suspects is the devonian from rockford Iowa. Once in a while I get them mixed in by mistake. 

8 and 9 and your specimens are rhynchonellids. A few species are present in the Decorah shale and can be difficult to tell apart, though general shell shape and the number of costae can help. 

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On 2/23/2021 at 8:07 PM, Tetradium said:

Heck I have a few that frustrates me. First one maybe a new species of Pionodema or Doleriodes? The weird thing is they all are pretty constant in size and are very inflated compared to Doleriodes pervetus while having that inconsistent line similar to some Pionodema subaequata. Second picture for a while was with the other regular rhy family and looks much like them until one day I found those 3 that had that transverse ridges like Lepidocyclus which hadnt been reported from Minnesota at all. Are they Lepidocyclus or somehow much better preserved than vast majority of their kind?   

You haven't included a scale and I'd need better close-up pictures of each specimen in the first photo, but I think they're likely to be Pionodema subaequata though the one bottom left could be Doleroides pervetus. They can be very difficult to tell apart. 

Again, for the rhynchonellids a scale is necessary but I'm pretty sure these are not Lepidocyclus. The top one is probably a Rhynchotrema and the others maybe Rostricellula. Costae counts might help.

This page may be of some use http://www.thefossilforum.com/index.php?/topic/78974-adams-ordovician/page/21/#comments

 

 

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Just now, Tidgy's Dad said:

You haven't included a scale and I'd need better close-up pictures of each specimen in the first photo, but I think they're likely to be Pionodema subaequata though the one bottom left could be Doleroides pervetus. They can be very difficult to tell apart. 

Again, for the rhynchonellids a scale is necessary but I'm pretty sure these are not Lepidocyclus. The top one is probably a Rhynchotrema and the others maybe Rostricellula. Costae counts might hekp.

 

Im having trouble trying to find my MM ruler. I will try to get back at you. 

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On 2/23/2021 at 8:56 PM, Tetradium said:

Not long after I posted the last two pics and took a short nap it popped in my mind that #1 could be Decorah version of Oepikina minnesotensis. From what I found from the Stroph family, at least for Minnesota I found a easier way to describe the different genus (except for rarer genus that I hadnt found yet. Strophomena is the most classic half moon shape of the family. Sowerbylus is like if you take a dough, shape it in a half moon then stretch from both sides. Rafinesquina is like if you take the dough shaped like half moon and stretch the circle part outward. Oepikina is like if you shape the half moon dough just like a regular shovel. 

See page 10 of the thread I linked to you for Oepikina minnesotensis from the Platteville Formation.

In the Decorah there is also Oepikina inquassa which is featured on page 21. 

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