Hustedia mormoni brachiopod from Kansas

Hustedia mormoni is a small rynchonellid type brachiopod that is common in Pennsylvanian aged rocks. This specimen came from Kansas, but that is all the label says. I found this specimen in the Yale Collection that has a provenance of: Late Pennsylvanian, Virgilian, Shawnee Grp, Oread Ls.

Brachial valve

Anterior

Pedicle valve

Posterior

Profile

Here is another link to a specimen from Missouri.

Derbyia

Another very large Brachiopod that I've acquired in estate sales is Derbyia. This member of the Orthotetida order lived primarily from the Carboniferous to the Permian. This particular specimen comes from the Wolfcamp series of Kansas. The overall look of the shell is rounded with an almost globular shape. Other than the large size and plentiful thin ribs the most notable feature is the back of the shell where the Pedicle and Brachial valves meet.




Here you can see a narrow, flat triangular shaped interarea which is unsual for brachiopods and there is not a clear pedicle exit hole at the hinge line. The pedicle was a muscle or series of threads that extended out of a hole in the pedicle valve and enabled the Brachiopod to attach itself to a surface. The current theory is that the pedicle threads extended through many small holes at the very tip of the pedicle valve. This would explain the deep interarea that would expand and get wider at the hinge as the animals shell grew.

Reticulatia

During the Carboniferous and Permian period there were a group of Productid Brachiopods that grew to large sizes and had some odd body adaptations. Below are pictures of a genera called Reticulatia from the Permian aged Wolfcamp series of Kansas. These Brachiopods are identified best by the cross hatching pattern on their shells formed by crossing ribs and rays. You can see the pattern very clearly in the shell below.






This second specimen got to a ripe old age and has a very deep lip. Apparently the brachial valve grows generally flat but as they get older, instead of continuing to grow perpendicular, it parallels the pedicle valve and forms an exaggerated edge along the lip between the valves.