Ordovician brachiopods from Kentucky

[connorp]

I collected these brachiopods from the lower Kope Formation (Late Ordovician) in northern Kentucky. I am leaning towards Zygospira modesta but was hoping for a second opinion. @Misha @Tidgy's Dad Thanks for any help.

 

[Tidgy's Dad]

I can't see clearly enough to do a plication count, but, yes,, at least some of these would appear to be Zygospira modesta. The general size, shape, fold and sulcus appear correct. 

Nice hash. 

@Peat Burns is the expert on this species. Tony? 

Edited July 13, 2022 by Tidgy's Dad

[Peat Burns]

5 hours ago, Tidgy's Dad said:

@Peat Burns is the expert on this species. Tony? 

Thanks, Adam.  I'm not an expert, I just happened to use my photo of that taxon for my Avatar 

 

They look more or less like Zygospira to me.  There are two species in the type area of the Cincinnatian, Z. cincinnatiensis and Z. modesta, but the former is only known from the upper Kope and Fairview formations (so that probably eliminates it as a possibility given that Connor's specimens are from the lower Kope).  Z. modesta is typically 5 mm wide, while Z. cincinnatiensis is usually twice that in width (those in Connor's photo look bigger than 5 mm, but that may be due to the scale not being in the same plane as the brachiopods).  By my count, Z. modesta has about 20 - 21 plications.  Z. cincinnatiensis has fewer.

 

Here is a plate I made from specimens of Z. modesta that I collected in the Liberty Fm. "butter shale" at St. Leon, IN, for comparison:

 

[connorp]

Thanks Tony @Peat Burns. The largest is maybe 6mm, and the more exposed individuals do look to have around 20 plications. So a good match.