Macraster sp. echinoid from the Duck Creek formation of Texas

Not only does the Duck Creek formation have ammonites, it has some echinoids as well. I found a couple of nicely inflated specimens of the irregular echinoid Macraster. I sent pictures of my find to a friend in Texas, who is familiar with the Duck Creek formation, and he said they could be either M. elegans or M. washitae. Macraster has a suboval shaped test with a sub rectangular cross section. The adapical surface has the typical five arm imprint of the ambulacra which is where the feet of the animal would have extended from. There is a small oval shaped opening in the posterior of the test called the periproct which is where the anus of the animal would have been. On the underside, or adoral surface, is the opening for the animals mouth called the peristome.

When I was a kid I called echinoids with this shape "sea biscuits".

Specimen #1 is a little water worn.
Adapical surface

Posterior

Left profile

Anterior

Right profile

Adoral surface

Specimen #2 is missing some of the test on the adoral surface
Adapical surface

Posterior

Left profile

Anterior

Right profile

Adoral surface

The only other Echinoid evidence that I found was this isolated piece from a regular echinoid.

The above specimens come from the Duck Creek formation which is Cretaceous (Albian stage) in age.

Neithea texanus pelecypod from the Duck Creek formation of Texas

This is the pelecypod Neithea texanus from the Duck Creek formation of Texas. I found it in a creek in North Texas last fall. It looks very similar to a scallop but this particular specimen is missing the small "ears" that normally are present next to the beak and are part of the hinge line. Otherwise the shell has a triangular outline with a convex right valve and a slightly concave to flat left valve. There are strong, wide ribs on both valves and the rib pattern is reflected in the margin between the valves.

Right valve

Anterior

Left valve

Posterior

Profile

This specimen comes from the Duck Creek formation which is Cretaceous (Albian stage) in age.

Eopachydiscus sp. ammonite from the Duck Creek formation of Texas

I found another type of ammonite, in the north Texas creek bed I was exploring, called Eopachydiscus sp.   I found a large number of them, in fact, but as many were sizable and heavy I only packed out one. I saw some that were well over 18" in diameter, approaching 24"! The specimen I chose to keep is about 8-9" in diameter, 3" thick and had some of it's sutures showing as well as oyster spats glommed onto it. What I don't know is if the oysters colonized the actual shell surface or if the original shell had already fossilized, dissolved away and left a steinkern as a base for them.

This specimen comes from the Duck Creek formation which is Cretaceous (Albian stage) in age.

Mortoniceras sp. ammonite from the Duck Creek formation of Texas

Before I started on my adventure in Oklahoma I landed in Dallas and drove north to a site that a good friend had suggested I visit. It was a creek that exposed the Duck Creek formation (Cretaceous, Albian stage) in a couple of spots. Having never collected in Texas before, but seeing plenty of field reports from those who had, I knew the Duck Creek formation should produce some nice fossils. I was not wrong. I found four specimens of the ammonite Mortoniceras sp. washed out in the creek bed. Mortoniceras can be identified by the prominent ribbing along the shell and strong rostrum. There are a couple of species of Mortoniceras and I'm not good enough to tell them apart so I will keep these labelled as Mortoniceras sp.

Specimen #1

Specimen #2

Glyptorthis costella brachiopod from the Viola formation from Oklahoma

The last, identifiable, fossil that I found during my brief visit to the roadcut in Oklahoma that exposed the Viola formation, is the brachiopod Glyptorthis costella. It has a subrectangular shape with valves that are equally convex and decorated with many fine, closely spaced striae. The margin of the valves is flat with no obvious fold/sulcus structure. The posterior of the shell has a nearly flat, wide interarea. Both valves are recurved in the umbo with the brachial valve moreso than the pedicle valve.

Brachial valve

Anterior

Pedicle valve

Posterior

Profile

This is a loose pedicle valve that I found.

The interior of the shell is nicely preserved with the muscle scars

These specimens comes from the Viola formation which is upper Ordovician (Sandbian to Katian stage) in age and overlies (unconformably?) the Bromide formation. I found them in a road cut along US 177, south of Sulphur, Oklahoma.