Tuesday, September 1, 2015

Chesapectin jeffersonius pelecypod from the Yorktown formation of Virginia

I acquired this shell at a rock/fossil/mineral show this past spring from someone who collected it themselves. It's a Chesapectin jeffersonius pelecypod from the Yorktown formation (Neogene, Pliocene epoch, Zanclean stage) of Virginia and was found along the James River.  The shell is enormous and I can just imagine what the scallops would have tasted like! It's only a single valve, I'm not sure if it is the left or the right but was a host to some epibionts. There are large barnacles (Balanus concavus), barnacles spats and some corals (Septastrea marylandica). All in all it's a terrific specimen that gives evidence of the environment that it lived in.

Shell exterior
Shell interior

I think these small holes are the traces from the boring sponge Cliona sp.

A better view of the huge barnacles

and some shots of the corals.

Corals with Cliona sp. boring sponge traces

Sunday, August 30, 2015

Sellithyris sella brachiopod from the Clape Massif of France

I really like the look of this next Brachiopod. It's a Sellithyris sella from the Aptian stage of the Cretaceous (found at the Clape Massif near Narbonne, France) that has part of the shell replaced by the "mineral" Beekite (which is a variety of Chalcedony, itself a variety of Quartz). That and the colors of the shell give it a lot of visual interest beyond the shell itself.

Sellithyris sella is a terebratulid brachiopod that is oval in shape when viewed from the top or bottom.It has a beak with a round foramen on the pedicle valve. Both valves are smooth and convex with a simple "w" shaped fold and sulcus structure on the anterior margin.

Pedicle valve

This fossil reminds me of another terebratulid brachiopod called Cererithyris arkelli but that species lived during the Bathonian stage of the Jurassic, about 50 million years apart.

Friday, August 28, 2015

Two gastropod steinkerns from the Lime Creek formation of Iowa

I found two gastropod steinkerns in my collection of Lime Creek Formation fossils from Rockford fossil Park in Iowa. They caught my attention as I was sorting the fossils I have from there to find duplicates I could send to a friend in Germany.

The first specimen is a Bellerophon sp. steinkern. Gastropods of this genera generally have a wide flaring opening to the body chamber and the shell whorls imbricate (directly overlap) upon themselves. The flared portion of the shell is missing on this steinkern but the whorls are imbricated.

Anterior view
Left side profile
Posterior view
Dorsal view
Ventral view

The other steinkern specimen is a gastropod called Floydia sp. whose whorls are not imbricated but appear stacked on top of each other. As this is an internal steinkern it is impossible to tell if the genera is correct much less determine the species.

Left profile
Anterior view
Dorsal view
Ventral view

Both of these specimens come form the late Devonian aged Lime Creek formation (Fransian stage).

Wednesday, August 26, 2015

Coelospira concava or Atrypina imbricata brachiopod from the Kalkberg formation of New York

This is the last fossil that I am profiling from the Kalkberg formation for now. I'm very surprised at the number of species that I found from this formation considering that I have only visited it once and only at a single roadcut. The honor of being last goes to a mystery brachiopod. The shell is semielliptical with a convex pedicle valve and concave brachial valve. Both valves have very strong plications but no fold/sulcus structure. There are prominent growth lines visible towards the edges of the margins. The pedicle valve appears to have a beak and umbo.

Pedicle valve
Brachial valve

Hall lists two species that look similar to the above fossil, Leptocoelia concava (since updated to Coelospira concava) and Leptocoelia imbricata (Since updated to Atrypina imbricata), in the "Paleontology of New York", Vol 3, pg. 245-246, pl. 38, fig. 1-13. Based on the pictures in that volume I am inclined to call my fossil Atyrpina imbricata due to the presence of the growth lines which is indicative of the species.

This specimen was collected from the Kalkberg formation (Devonian, Lockhovian to Pragian stage) at a roadcut near Schoharie, NY.

Monday, August 24, 2015

Paleschara or Leioclesma bryozoans from the Kalkberg formation of New York

These little bryozoan "chips"were interesting to find and I'm trying to figure out what genera they are. They bear a resemblance to Paleschara sp. but they are not encrusting a shell, which is how I find them most often. they could also be another genera called Leioclesma sp. which looks similar but does not have the encrusting habit. Both of the below specimens did start out colonizing a small hard surface with the first specimen growing over an ossicle from a crinoid stem.

Specimen #1 - Dorsal surface

Profile view showing just how flat this fossil is.
Ventral surface

Specimen #2 - It's not as clear as to what the second specimen settled on. It could be a fragment of another bryozoan or possibly an ostracod carapace. Dorsal surface
Ventral surface

Both of these specimens were collected from the same roadcut near Schoharie, NY from the Kalkberg formation (Devonian, Lockhovian to Pragian stage).