Thursday, March 29, 2012

Pseudoatrypa from the Windom Shale

I was surprised at the large size of the Pseudoatrypa that I found at the Penn Dixie site. Specimens the size of a walnut are very common and found in the same layers that Spinatrypa occurs.

Pedicle valve

Anterior

Brachial valve

Posterior

Profile


Specimen #2
Pedicle valve

Anterior

Brachial valve

Posterior

Profile


As a comparison, here is the second specimen of Pseudoatrypa next to a Spinatrypa from the same layer. The Spinatrypas seemed to get larger than the Pseudoatrypa.

The specimens shown above came from the Windom shale member of the Moscow formation which is middle Devonian (Givetian) in age.
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2 comments:

  1. NathanMarch 29, 2012 at 7:20 AM

    Hey dave that is a large one. Do you know if Atrypa is also found there in the Windom or the Wanakah?

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  2. DaveApril 11, 2012 at 4:10 AM

    Hey Nathan, Yes, I think Atrypa is found in the Windom and Wanakah. It can be tough sometimes to discern them from Pseudoatrypa but they should be flatter with less of a dome.

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