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Tidgy's Dad

Hello, friends. Hug.gif.3d8f0223d5c3b0c2d15aecff8b65c276.gif

This specimen comes from the Catskills, New York and is from the Helderberg Group, Lochkovian or Lowermost Early Devonian in age. 

It could be from Becraft Mountain.

It's not a rhynchonellid, it's too flat and there's no notable fold or sulcus. 

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It develops second second order costellae half way toward the anterior margin

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I have a couple of not very convincing thoughts but would be very interested in your opinions. 

Thank You. :beer:

 

 

 

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IsaacTheFossilMan

Very unfamiliar with this locality, but Desquamatias sp.? Definitely an atrypid.

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24 minutes ago, IsaacTheFossilMan said:

Very unfamiliar with this locality, but Desquamatias sp.? Definitely an atrypid.

Why definitely Atrypid? I don't really see anything pointing to that personally. When I first saw this my first thought was Strophomenid

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IsaacTheFossilMan
30 minutes ago, Misha said:

Why definitely Atrypid? I don't really see anything pointing to that personally. When I first saw this my first thought was Strophomenid

 

Strophomenid also crossed my mind, but it doesn't have the perpendicular wings typical of one - atrypids are also more frequently known from this sort of locality (from a quick search of literature). The overall directions of the divergence of the costellae from the beak also lend themselves towards atrypida, at least from what I can see.

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Tidgy's Dad

Unfortunately, it is not possible to be certain if this specimen has a strophic hinge or not. 

I won't rule out atrypid, though I think some of the athyrids, strophomenids and even pentamerids might be a better match. 

Thank you for your comments @IsaacTheFossilMan and @Misha

Desquamatia does not occur here, I think? 

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IsaacTheFossilMan
4 hours ago, Tidgy's Dad said:

Desquamatia does not occur here, I think? 

 

I beg your pardon, you are indeed correct. :tiphat:

 

However, East North American atrypid are incredibly poorly documented, and, as shown by Johnson (1970)(1990) and Day (1992)(1996b), late Givetian assemblages highly correlate to the brachiopod fauna found in Frasnian assemblages. As shown by Day (1998), it is highly possible Desquamatia, highly abundant in NA late Givetian fauna, which lots initially went locally extinct in NA, but migrated back from Canada constantly during the Frasnian.

 

4 hours ago, Tidgy's Dad said:

athyrids, strophomenids and even pentamerids


I initially ruled out athyrids and pentamerids due to less prominent growth lines, but, as you say, without a certainty on the presence (or lack of) of a strophic hinge, it will be virtually impossible to determine what this is.

 

On the right of the beak (looking at the outside), there appears to be a virtually unbroken hingline and wing:,

image.png.0ac1e23b79b47e88a96f2355d17520b8.png

which led me to believe it must be an atrypid.

 

Depressingly, due to lack of documentation, it might not be possible - but strophomenid/atrypid seems a strong bet right now.

 

:P 

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IsaacTheFossilMan

On a separate point - congrats on the beautiful find, Adam! You and the ol' Tidge-meister must be awfully proud. :wub: 

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49 minutes ago, IsaacTheFossilMan said:

 

I beg your pardon, you are indeed correct. :tiphat:

 

However, East North American atrypid are incredibly poorly documented, and, as shown by Johnson (1970)(1990) and Day (1992)(1996b), late Givetian assemblages highly correlate to the brachiopod fauna found in Frasnian assemblages. As shown by Day (1998), it is highly possible Desquamatia, highly abundant in NA late Givetian fauna, which lots initially went locally extinct in NA, but migrated back from Canada constantly during the Frasnian.

 

Well, I am sure august names like A.J. Bucot would beg to differ! ;) Bucot's invaluable work on brachiopods in the ENA remain the standard in our understanding of brachs. For Devonian brachiopods here, we are spoiled for choice be it the work of Kesling & Chilman, Stumm & Wright, et al. 

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