Decorah Shale, heavy on Brachiopods

[Tetradium]

26 minutes ago, Tidgy's Dad said:

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. 

Heres my pics. First one I just changed genus. Zygospira recurvirostris They're very sphere shaped and inflated compare to the other. By compare Rhynchotrema and Rostricellula are more flatter.  

Second Picture was what I had for a long time assigned to first picture. Rhynchotrema ainselei. Those are much wider and didnt look anything like any orthid and have much more ribs than any other in their family. Sulcus is much more extreme as well too.

 

Third Pics are what I had labeled Doleriodes pervetus for top and Hesperorthis tricenaria for bottom. You can see Hesperorthis tricenaria had much more coarse ribs by comparation. 

 

Forth pic is what I had labeled Pionodema subaequata. Much more finer ribs but a few looks a bit more coarse. 

[Tetradium]

1 hour ago, Tidgy's Dad said:

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. 

By comparation heres what I had labelled Oepikina inquassa for photo #1 and Oepikina minnesotensis for photo #2. 

I just lump the very coarse and lumpy shells in with Oepikina inquassa. After viewing the descriptions and a few bad pics, I couln't find any Furcitella scofieldi and Bellimurina charlottae. 

 

#2 is what I had labelled Oepikina minnesotensis. From what I had seen they're smaller than O. inquassa and more uniform in shape. 

 

The only other medium to large brachiopod I couldn't find was supposedly rare as well. Vellamao americana which looks like a cross between Strophomena and Hesperorthis tricenaria. 

[Tidgy's Dad]

1 hour ago, Tetradium said:

Heres my pics. First one I just changed genus. Zygospira recurvirostris They're very sphere shaped and inflated compare to the other. By compare Rhynchotrema and Rostricellula are more flatter.  

Second Picture was what I had for a long time assigned to first picture. Rhynchotrema ainselei. Those are much wider and didnt look anything like any orthid and have much more ribs than any other in their family. Sulcus is much more extreme as well too.

 

Third Pics are what I had labeled Doleriodes pervetus for top and Hesperorthis tricenaria for bottom. You can see Hesperorthis tricenaria had much more coarse ribs by comparation. 

 

Forth pic is what I had labeled Pionodema subaequata. Much more finer ribs but a few looks a bit more coarse.

It might be a good idea to start your own thread. 

Nothing like Zygospira and too big. I say again these are rhynchonellids and you need to count the costae. Some of them may be Rhynchotrema ainslei but only if they have five costae on the fold, otherwise they're likely Rostricellula minnesotensis which is often very rounded. Don't forget that brachiopods can be very variable in shape and number of costae etc. even within the same species.

The second photo shows broader specimens with many more costae and look like Rhynchotrema laticosta from the Cummingsville, but if you are certain that they are Decorah Shale, they are more likely to be Rhynchotrema wisconsinensis. 

Third pic looks like Pionodema subaequata. Not sure about the bottom ones, but seem to be rhynchonellids.

Fourth pic would seem to be a mix of P.subaequata and Doleroides pervetus.

 

[Tidgy's Dad]

1 hour ago, Tetradium said:

By comparation heres what I had labelled Oepikina inquassa for photo #1 and Oepikina minnesotensis for photo #2. 

I just lump the very coarse and lumpy shells in with Oepikina inquassa. After viewing the descriptions and a few bad pics, I couln't find any Furcitella scofieldi and Bellimurina charlottae. 

 

#2 is what I had labelled Oepikina minnesotensis. From what I had seen they're smaller than O. inquassa and more uniform in shape. 

 

The only other medium to large brachiopod I couldn't find was supposedly rare as well. Vellamao americana which looks like a cross between Strophomena and Hesperorthis tricenaria. 

 

Mix of stuff, can't see most of them clearly enough but there are Strophomena and Rafinesquina in here for sure.

Please refer to the links to my thread i posted you and you should be able to identify all of these. 

[Tetradium]

2 minutes ago, Tidgy's Dad said:

Mix of stuff, can't see most of them clearly enough but there are Strophomena and Rafinesquina in here for sure.

Please refer to the links to my thread i posted you and you should be able to identify all of these. 

I will be busy until Sunday or Tuesday so take your time! I will photograph my 3 Strophomena species, 2 Rafinesquina species, 2 cincinnetina species, 1 dinorthis species, 1 Paucicrura species, 2 Platystrohia species. The other forum would takes a lot of time so I will check through them the next few days so we will see. One, Van whatever hadnt been listed for Minnesota but I will have to search for that one link - I knows Plaestomys is obscure and only for northern Europe along with 2 other genus but I cant remember what the other two genus are. Maybe Dalmanella but not sure. 

 

Wait I missed Diorthelasma weissi and Dalmanella sculpta. 

[Tetradium]

By the way I hadnt even taken photos of the more zygospira/rhynchotrema/Rostricella ones which had fewer ridges and are flatter. That will takes more time to count anyway. 

24 minutes ago, Tidgy's Dad said:

Mix of stuff, can't see most of them clearly enough but there are Strophomena and Rafinesquina in here for sure.

Please refer to the links to my thread i posted you and you should be able to identify all of these. 

 

[Tetradium]

22 minutes ago, Tetradium said:

 

 

35 minutes ago, Tidgy's Dad said:

Mix of stuff, can't see most of them clearly enough but there are Strophomena and Rafinesquina in here for sure.

Please refer to the links to my thread i posted you and you should be able to identify all of these. 

I forgot to add something else - yes brachiopods can be very variable - they just lumped 5 or 6 genus and species for Devonian spifers into one genus and one species for Iowa because that particular species is so high variable, either having wings, one half very inflated with nearly flat base, etc.