Geobulletin alpha

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 [...]

Reticulariina sp. ? brachiopod from the Chainman formation of Utah 

I believe this next fossil is a Reticulariina sp. brachiopod but am not sure of the species. It comes from the Chainman formation of Utah which is lower Carboniferous in age (Mississippian epoch, Visean stage of the ICS or Mississippian period, Chesterian stage in the US). The shell is small, with a very convex pedicle valve and a flat to slightly convex brachial valve. It sort of resembles a Cyrtia sp. type brachiopod that occurred in the Devonian. Each valve has very coarse plications with [...]

Anthracospirifer sp. brachiopod from the Chainman formation of Utah 

I believe this next brachiopod fossil is Anthracospirifer sp.. It comes from the Chainman formation at Conger Springs in Utah. The shell is missing part of a "wing" but enough is left to help identify it. The pedicle and brachial valves are equally convex, rectangular shaped and have coarse plications. A sulcus on the pedicle valve corresponds with a single fold on the brachial valve. The pedicle valve has a wide interarea with a recurved beak.Brachial valveAnteriorPedicle [...]

Cleiothyridina hirsuta brachiopod from the Chainman formation of Utah 

Looking very much like an Athyris sp. brachiopod, this fossil is Cleiothyridina hirsuta.  It is a rounded to subovate shell with both the pedicle and brachial valve equally convex. The surface of each valve has concentric growth lines but no obvious costae or sulcus.Brachial valve AnteriorPecidle valvePosteriorProfileI used the reference "Brachiopoda of the Amsden Formation (Mississippian and Pennsylvanian) of Wyoming.", MacKenzie Gordon, Jr., 1975 pg. 56, plate 7, fig 31, 38-40, 42-45, [...]

Inflatia sp. brachiopod from the Chainman formation of Utah 

I found this specimen of a spiny productid brachiopod at Conger Springs, Utah. I believe it is an example of the genus Inflatia. I am unsure as to the species because the preservation is not the best. It was a spiny brachiopod but not as spiny as a similar genus, Juresania.  The pedicle valve is very convex while the brachial valve is flat to slightly convex and the margins of both meet at a 90 degree angle to the brachial valve.  Both valves are decorated with linear costae but only [...]

Crurithyris sp.? brachiopod from the Chainman formation of Utah 

This next brachiopod looks very similar to a genera called Crurithyris that is present in the Pennsylvanian. I can't locate any literature or examples from the Chainman formation at Conger Springs, Utah that indicate this could be any other genera. So I am tentatively labeling this as Crurithyris sp. The shell is small, wider than long with a very convex pedicle valve and a slightly convex brachial valve. The valves are smooth with no obvious ornamentation. The pedicle valve recurves back over [...]

Eumetria costata brachiopod from the Chainman formation of Utah 

While search for fossils at Conger Springs, Utah I found lots of examples of these little brachiopods called Eumetria costata. They are small shells that are longer than wide with the widest point about midway between the umbo and the anterior margins. Each valve is roughly equally convex and has around 20 radiating costae on the surface. The umbo extends beyond the brachial valve and curves slightly to the point where the circular formen opening is located.Specimen #1 - Brachial [...]

Composita elongata brachiopod from the Chainman formation of Utah 

Another Composita species that I found in the Chainman formation of Utah is Composita elongata. This species is narrower than some but this particular specimen has a very strong fold and sulcus that is well developed. According to MacKenzie (see below for reference), C. elongata may intergrade with C. subtilita (see previous post). This means that the two species sometimes share the same form but remain distinct.I used the reference "Brachiopoda of the Amsden Formation (Mississippian and [...]

Composita subtilita brachiopod from the Chainman formation of Utah 

Today I have a specimen of what I believe is Composita subtilita from the Carboniferous (Mississippian epoch, Visean stage of the ICS or Mississippian period, Chesterian stage in the US) rocks of Utah. It was found near Conger Springs which is about 63 miles (as the crow flies) west of the town of Delta in Millard County. The rocks exposed at Conger springs are the Chainman formation and are the youngest Mississippian layers before changing to the Pennsylvanian. The shell of Composita subtilita [...]