Thursday, March 31, 2011

Platystoma from the Waldron Shale

This large gastropod is called Platystoma. This was a loose fossil that was purchased along with the plates of Waldron Shale at the DMS show. It too is from the Waldron Shale and the size is typical for the species and formation.

I like that the shell has been colonized by a Bryozoan which forms some neat patterns with it's growth.

I'd like to try and clean the shell off some more and see if I can find any more Byrozoan colonies. As it is, I don't know if they colonized the shell before or after the snail died.

Tuesday, March 29, 2011

Stegerhynchus from the Waldron Shale

This next Waldron Shale Brachiopod is somewhat common and is called Stegerhynchus sp. The ID is based on discussions with Mike over at Louisville Fossils and Beyond.

Pedicle Valve


Brachial Valve



This is another Brachiopod that came from the slabs of Waldron shale I purchased from the Delaware Mineralogical Society show.

Sunday, March 27, 2011

Rhynchotreta (?) from the Waldron Shale

Here is another of the mysterious Brachipods from the Waldron Shale. I think this is a Rhynchotreta sp. shell based on this post by Mike at Louisville Fossils and Beyond.

Brachial Valve


Pedicle Valve



As you can see, it is very long and narrow which may mean it's not Rhynchotreta but I'm not sure. One of the neat anatomical features of this shell is the fact that the brachial valve ends well before the pedicle valve does to allow the pedicle space to stick out (the small round hole).

Friday, March 25, 2011

Dalejina (?) from the Waldron Shale

At a recent Fossil & Mineral show put on by the Delaware Mineralogical Society (DMS), I purchased a couple of pieces of Silurian aged Waldron Shale. I'd bought them as they had Crinoid "roots" preserved but while cleaning them off a number of small Brachiopods came loose. One of them looks almost like a Rhipidomella brachiopod but further study, and conversations with Mike at Lousiville Fossils and Beyond, have led me to think this might be Dalejina instead.

Brachial Valve


Pedicle Valve



The reason for my hesitance to name this fossil a Rhipidomella is that the shape and size of the shell don't seem to correspond to what I've found elsewhere. Rhipidomella is more rectangular in shape while Dalejina is rounder. Dalejina is in the same family as Rhipidomella and is known from the Rochester Shale of New York which is often seen as analogous to the Waldron Shale of Indiana and Kentucky.

I found a plate in the book Brachiopods of the Bois Blanc Formation in New York by A.J. Boucott and J.G. Johnson that shows Dalejina. Plate 1, figures 11-27 show both internal and external pictures of the shell.

The website for Primitive Worlds, a group who quarry the Rochester Shale, has a picture of Dalejina that seems to fit my specimen as well.

Wednesday, March 23, 2011

Tentaculite mass grave

While exploring an exposure of the Upper Silurian/Lower Devonian aged Keyser formation in central Pennsylvania, I came across these chunks of rock that seem to record a mass die off. What I found are thousands of Tentaculite fossils all pointing in the same direction.

Tentaculite fossils are a mystery to Paleontology. Some think they may be worm tubes, others say they are related to jelly fish or corals. Either way, this rock has a story to tell.

Here is a side view of the above rock. The thickness of the layer is approximately 1 inch.

From what I can see, this is a relatively thick layer of these fossils and all of the shells are pointed in the same direction. I interpret the shell orientation as indicative of the current on the bottom of the sea floor. As the water swept over the shells it oriented them with the narrow end pointing in the direction of the current.

As to why the layer is so thick and dense is another matter. It could record a mass die off of the Tentaculites due to a red tide or some other sudden change in their environment. It could also represent years of accumulation of the shells such as at a wave base or a sheltered area.

Here is another piece of rock from the same locality.

Here is the side view of the above rock. The Tentaculite layer is thinner, only a few millimeters at the very top, but you can see some nice lamination in the rest of the limestone. Alternating layers of dark and light limestone may record years or seasons.

I wasn't able to locate the layer these pieces of rock came from so I don't know the full extent or thickness of the Tentaculite grave. The next time I visit the site I will try to find out more.

Saturday, March 19, 2011

Clypeaster from Italy

Clypeaster echinoderms can get very large and this specimen fits the bill. It's from the Miocene of Italy and was sent to me by my friend, Gery. It's dimensions are 5 inches long, 4.5 inches wide and 2.5 inches tall.

Normally these echinoderms, also called "Sea Biscuits", can be found crawling on the sandy bottom or sometimes burrowing into it. They typically have a fine coating of small spines that they use to walk on. They are extant (still found alive today) in Caribbean shallows among kelp beds.

Want to see how one of these fossils is prepped and preserved? Click here to go to You Tube for a great video.

Thursday, March 17, 2011

A couple of Eocene shells from Paris

I was going through some fossils that I received from my generous friend in France, Gery, and I happened upon these gastropod shells. They hail from Lut├ętian which is near Paris. They are Cassidaria nodosa and are from the Eocene.

During the Eocene the region in which Paris now rests was a shallow sea which held a rich diversity of marine life. Thanks, Gery, for the fossils!

Tuesday, March 15, 2011

Flexicalymene from Mt. Orab

The Ordovician aged limestones around Cincinnati are chock full of fossils and one of the most sought after is the trilobite Flexicalymene. I have yet to be lucky enough to find one myself but here is a partially enrolled specimen that I recently bought at a fossil show.

The fossil comes from the Arnheim member of the Richmond Formation and was found at Mt. Orab, Ohio. The site the fossil was found at is regionally famous for how productive it is at producing trilobite fossils. It is on private property and only clubs are allowed in and that only occurs one a year or so.

Sunday, March 13, 2011

Ilymatogyra arietina

Another oyster found in the Cretaceous sediments of Texas is this curled specimen. Below is what I believe is a Ilymatogyra arietina based on the book "A Field Guide to Fossils of Texas" by Charles Finsley, plate 58, photo 192.

This fossil comes from the Lower Cretaceous aged Grayson Fm., Denton County, Texas.

As a comparison, here are the three Texas oysters that I've detailed in the last few posts side by side. From left to right: Texigryphaea navia, Texigryphaea marcoui, Ilymatogyra arietina

Friday, March 11, 2011

Texigryphaea navia

Today, another fossil oyster from the Texigryphaea genus. Below is what I believe is a Texigryphaea navia based on the book "A Field Guide to Fossils of Texas" by Charles Finsley, plate 57, photo 182.

Note the more flattened profile in comparison to the Texigryphaea marcoui that I had in my last post. This fossil is from the Lower Cretaceous aged Grayson Fm., Tarrant County, Texas.