Rhipdomelloides oblata brachiopod from the Bois d'Arc formation of Oklahoma

Perhaps the most common fossil brachiopod to be found in the Bois d'Arc formation is Rhipidomelloides oblata. Most are small but some can get about an inch in width. The shell is rounded to subrectangular with both valves generally convex. A gentle curve is sometimes present in the anterior margin. The pedicle valve has a beak that recurves over the brachial valve. Both valves have fine striae and concentric lines decorating their surface.

Pedicle valve

Anterior

Brachial valve

Posterior

Profile

While this next fossil is somewhat large it is also compressed nearly flat which makes it more difficult to identify. I'm a fairly confident though that this too is a specimen of Rhipidomelloides oblata. The shell is rounded to ovate with both valves decorated with numerous fine costae. This specimen is flattened but in life both valves would have been slightly convex. The posterior is mostly obscured by matrix or by the shell being flattened.

Brachial valve

Anterior

Pedicle valve

Posterior

Profile

I wrote a post about similar specimens of Rhipdomelloides oblata from the Haragan formation.

I found the specimens shown on this page in the Bois d'Arc formation (Cravatt Member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc overlies the Haragan formation but both are the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

References: 
"Stratigraphy and Paleontology of the Hunton Group in the Arbuckle Mountain Region, Part V - Bois d'Arc Articulate Brachiopods " Amsden, 1958, Oklahoma Geological Survey Bulletin 82