Wednesday, February 3, 2016

Spiriferellina ? or Punctospirifer? brachiopod from the Chainman formation of Utah

Here is another mystery brachiopod from the Chainman formation of Utah. It is a triangular shaped shell which is longer than wide. Both valves have coarse folds that extend from the hinge line to the anterior margins with a simple fold and sulcus. The hinge line is flat and runs the length of the anterior margin. A small triangular shaped delthyrium is present on the anterior of the pedicle valve but it is only 1/2 the length of the hinge line. My initial speculation as to the identity of this shell was that it is a Punctospirifer sp. But while reading through some publications concerning Mississippian faunas in Western US formations, I came across a similar looking shell called Spiriferellina sp. I want to lean towards the latter name because it would be more appropriate for the region I found it in.  Still, without a complete shell or multiple examples I probably can not truly identify this specimen.

Brachial valve
Pedicle valve

This specimen came from the Chainman formation at Conger Springs (west of Delta), Utah and is Carboniferous (Mississippian epoch, Visean stage of the ICS or Mississippian period, Chesterian stage in the US) in age.

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