Platteville Brachiopods for Identification

[minnbuckeye]

My winter has been spent thinning and organizing some of my fossil formation collections. The Platteville Formation has been one of my favorites as it produces that occasional spectacular trilobite. My biggest problem has been with some brachiopod identification. Thankfully, @Tidgy's Dad,s Ordovician post  has made it relatively easy with the more common brachiopods. Finding great sources for the Platteville is hard. Many of the specimens shown today are MUCH smaller than the normal brachs from this formation. All are numbered and my measuring device is worn and didn't show through too well, so I added sizes. 

 

1 is Campylorthis like but not the same as my others.

 

 

2 is similar to Hesperorthis but the valve appears too round.

 

 

3, 4, and 11 are plump Strophomena like brachiopods with the height maximum midway, not toward the back as my other Strophomena are.

 

 

 

5 is a confusing Strophomena like brachiopod. It is deeply concave, not showing up well on this photo. It is opposite of the Oepikina which is convex. But their hinge lines are similar. Rafinesquina was a guess but no listing of it in the Platteville.

 

 

 

 

 

 

9 is very ornate!

 

 

 

 

12 reminds me of Zygospira but can not find mention of it in the Platteville. I considered Rostricellula but a sulcus is not present. 

 

 

13 is deeply concave, not captured well in the picture.

[Tidgy's Dad]

1. Yes, it's Campylorthis deflexa. Don't forget that brachiopods do grow to adult size very quickly, but we do find young and therefore small and even tiny ones occasionally. 

2. Right again, this is Hesperorthis tricenaria. Brachiopods can be very variable in morphology and I think the dip in this brachial valve, rather than a standard sulcus is quite distinctive.

3, 4 and 11.  before I go any further, I need to know the state in which these were found, please. The fauna can be different from Minnesota, Wisconsin and Illinois. 

Cheers, Mike, there are some lovely specimens there. 

[connorp]

9 is Glyptorthis (or Eridorthis, seen both) costellata. 8 might be too. Shape looks right but pictures are too exposed.

[Advantage]

Lovely Brachiopods , I enjoyed seeing them.

[minnbuckeye]

2 hours ago, Tidgy's Dad said:

I need to know the state in which these were found, please

 

Adam Thanks for helping out. These were from Morocco!!  (Wisconsin)

[minnbuckeye]

2 hours ago, connorp said:

Glyptorthis (or Eridorthis, seen both) costellata

 

@connorp, it sure looks correct but I still can not find it listed in the Platteville.

[connorp]

32 minutes ago, minnbuckeye said:

 

@connorp, it sure looks correct but I still can not find it listed in the Platteville.

From Kolata's book.

[Tidgy's Dad]

If it's Wisconsin, then those are Rafinesquina alternata. Byers and Gavin (1979) record Rafinesquina from the Platteville of Wisconsin and I have found other references that I can't recall right now. 

5. Must be Strophomena, a brachial valve, though it looks rather unusual.

6. Don't know. Interesting. 

7. Dinorthis sp. 

9. Won't argue with @connorp's informative post except to say that this is currently still Glyptorthis costellata; Eridorthis is a separate valid genus and thus the two are not synonymized. 

I also agree that 8 might be too, but it's overlit and I can't make out enough diagnostic features. 

10. Don't know. Possibly an Onniella. 

11. Rafinesquina alternata.

12. Rhynchotrema sp. There does appear to be a slight sulcus 

13 . Dinorthis again? 

 

 

Edited March 18, 2023 by Tidgy's Dad

[minnbuckeye]

Thanks for all of the help!!! Specimens are now labeled.

 

Mike