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Decorah Shale, heavy on Brachiopods


minnbuckeye

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A few weeks ago, just when we were inundated with the spring muddy season, I stopped at a site that features Decorah Shale with a little Platteville mixed in. If you haven't collected in the Decorah Shale, let me say it stays MUDDY even in a drought!! The site had been worked over for a finish grade. This means the site will soon be lost to vegetative overgrowth. :( So I proceeded to collect a 5 gallon bucket of mucky matrix to clean and examine at home, in case the weeds invade quickly. Here are some select finds from that bucket. 

 

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Wonderful diversity of brachiopods. :wub:

Beautiful photos. 

Life's Good!

Tortoise Friend.

MOTM.png.61350469b02f439fd4d5d77c2c69da85.png.a47e14d65deb3f8b242019b3a81d8160-1.png.60b8b8c07f6fa194511f8b7cfb7cc190.png

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Beautiful colours in there. Love it!

"Faith is to believe what you do not see; the reward of this faith is to see what you believe" - Saint Augustine

"Those who can not see past their own nose deserve our pity more than anything else."

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I, too, love the colours of your specimens - I especially like the pinkish Rafinesquina specimens, like this one: 

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:wub:

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I really like the colors on theses. I have the same fear about some sites I go to....there is always a fear of an expiration date. Beautiful looking brachs :)

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47 minutes ago, Bev said:

Your photography

 

@Bev, it is easier to take the time to do when you're stuck in the house. I have taken many many more photos of fossils and other subjects since the virus appeared. So here is a silver lining to that dark cloud.

 

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16 minutes ago, JamieLynn said:

What is this? 

JamieLynn, I find these frequently. They are little perfectly round balls less than 1/2 cm in diameter with no signs of attachment to something. My suspicion is a type of sponge, but who knows???? Maybe I will put it in fossil ID.

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Those small round objects stippled with pores are Hinda sp. sponges. Somewhat common in the Ordovician but they exist up through the Paleozoic as well.

 

oops, forgot to add the quotes.

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-Dave

__________________________________________________

Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPhee

If I'm going to drive safely, I can't do geology. - John McPhee

Check out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/

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@Shamalama, did you mean Hindia? Not much showed up looking for Hinda. Did these sponges attach to the bottom? I never can visualize a spot where attachment would occur.

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21 hours ago, minnbuckeye said:

@Shamalama, did you mean Hindia? Not much showed up looking for Hinda. Did these sponges attach to the bottom? I never can visualize a spot where attachment would occur.

Yup, Sorry, I meant Hindia. They didn't attach to the bottom I think they rolled along the bottom below wave base. Or perhaps they were able to float just a little above the sediment. Just my ballpark guessing, I really don't know for sure. 

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-Dave

__________________________________________________

Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPhee

If I'm going to drive safely, I can't do geology. - John McPhee

Check out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/

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@Tidgy's Dad, I have been trying to ID the Decorah Shale brachiopods  and have some  left. My searches lead to a bunch of dead ends.Lists of brachiopods are easy to find but often conflicting. Then to try and find a picture for those species listed is frustrating. Do you recognize these?  Or know of a VISUAL reference  for Decorah brachiopods?   THANK YOU for looking! 

  

Mike 

 

1. Doleroides pervetus  15mm   The one on far right is different. Never noticed that before. It looks like an atrypa. Otherwise, the ribbing on these seem much finer than pictures of Doleroides.2019-05-043.jpg.938c1330c178e5b3ed83c95470e81e7d.jpg 

2. Dalmanella sculpta  15mm

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3. Rostricellula minnesotensis 13mm about 24 costae

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 4.  Strophomena filitexta   30mm. I thought it was a Strophomena EXCEPT it is depressed in the middle of the outer edge (where another shell its touching it)

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5. Doleroides pervetus  18mm

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 6. Dinorthis pectinella  18mm

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 7. Diorthelasma  18mm

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8. Rostricellula minnesotensis  15mm

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 9. 25mm

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Chapter 4 of Robert Sloan's book "Minnesota Fossils and Fossiliferous Rocks" has both photos and drawings of brachs and bivalves. It is THE book to have for the Ordo in Minnesota.

 

The "Index Fossils of North America" Shimer and Shrock is nicely illustrated with photos and drawings also.

 

There is a guy in Red Wing who sells fossils on online who can identify pretty much all of the brachs by sight, I forget his name and he isn't on TFF nor does he want to be.

 

Yes, there are silver linings to this stay-at-home order. I've been doing a lot of gardening, bought a new camera (Nikon D3300) I'm trying to figure out, and yesterday I was making goat horn jewelry and attempting to do a photo shoot with Athena and Artemis - they move so much it is hard to focus!

Athena

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Artemis

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Arty showing off her moves!  LOL  :-D

 

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Last summer did I take you to the Valley of the Fisherites off Hwy. 16? Lovely spot with a Missouri Crossing - they paved right over a bed of Fisherites!

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The more I learn, I realize the less I know.

:wacko:
 
 

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Tanks Bev. Good suggestions. Do you have these books? Lovely caprine pics. Is the one pregnant? Not sure where the fisherite site is. Would love to see the Missouri crossing. The neighbor that has easement through our property talked me into letting them build a bridge across our trout stream. I relented (their architect convinced them to build a 3 1/2 ft high bridge) but in hindsight, should have forced them to put in the Missouri crossing. now the bridge just acts like a net catching all that floats downstream after a river rise. If you could let me know where that crossing (And fossils) is, I would like to visit the site and take some pictures.

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Yes, I have the books and if you would like to borrow them you are welcome. Stop by and we can drive separately and I will show you the site. A good rise on the creek and a downed tree will take the bridge out eventually. Then suggest a Missouri crossing.  :-)

 

The more I learn, I realize the less I know.

:wacko:
 
 

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Oh, and no she isn't pregnant. They are just fat goats. Yearling doelings. I don't want to milk anymore.  :-)

The more I learn, I realize the less I know.

:wacko:
 
 

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5 hours ago, minnbuckeye said:

Do you recognize these?  Or know of a VISUAL reference  for Decorah brachiopods?

 

 

Rice, W.F. 1987

The Systematics and Biostratigraphy of the Brachiopoda of the Decorah Shale at St. Paul, Minnesota.

Minnesota Geological Survey, University of Minnesota, Report of Investigations, 35:136-166  PDF LINK

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22 minutes ago, piranha said:

 

 

Rice, W.F. 1987

The Systematics and Biostratigraphy of the Brachiopoda of the Decorah Shale at St. Paul, Minnesota.

Minnesota Geological Survey, University of Minnesota, Report of Investigations, 35:136-166  PDF LINK

 

Thanks Piranha! This PDF is a fair amount of Sloan's book. Around page 177 you will find the brach pics. His book is much more readable though.  :-)

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The more I learn, I realize the less I know.

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14 minutes ago, Bev said:

Thanks Piranha! This PDF is a fair amount of Sloan's book. Around page 177 you will find the brach pics. His book is much more readable though.  :-)

 

 

Sloan 2005 is a great resource but it does not have a detailed section on the systematic paleontology of the Decorah brachiopods found in Rice 1987.

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9 minutes ago, piranha said:

 

 

Sloan 2005 is a great resource but it does not have a detailed section on the systematic paleontology of the Decorah brachiopods found in Rice 1987.

Well, if you go to the PDF you see it is written by Sloan, don't know who Rice is as s/he isn't listed as an author on this. Pics and drawings are in Sloan's book. I agree, not as detailed as this PDF of his, but for basic IDing, good. His book has a ton more pics though. But this is FREE!  And Sloan's book is not.  :-)

The more I learn, I realize the less I know.

:wacko:
 
 

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15 minutes ago, Bev said:

Well, if you go to the PDF you see it is written by Sloan, don't know who Rice is as s/he isn't listed as an author on this. Pics and drawings are in Sloan's book. I agree, not as detailed as this PDF of his, but for basic IDing, good. His book has a ton more pics though. But this is FREE!  And Sloan's book is not.  :-)

 

 

Please check the pdf again, the cited paper is not written by Sloan.  The bulletin was edited by Sloan and he only authored/coauthored 8 out of 26 papers.

 

Rice, W.F. 1987

The Systematics and Biostratigraphy of the Brachiopoda of the Decorah Shale at St. Paul, Minnesota.

Minnesota Geological Survey, University of Minnesota, Report of Investigations, 35:136-166  PDF LINK

image.thumb.png.057643b7f802546ac36f54061f691fe3.png

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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?  

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Life's Good!

Tortoise Friend.

MOTM.png.61350469b02f439fd4d5d77c2c69da85.png.a47e14d65deb3f8b242019b3a81d8160-1.png.60b8b8c07f6fa194511f8b7cfb7cc190.png

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