Tuesday, May 26, 2020

Mediospirifer audaculus brachiopod from the Moscow formation

Mediospirifer audaculus is a very common brachiopod from the middle Devonian and I've found it at the Penn Dixie site, in the Silica shale formation, the Centerfield mbr. of the Ludlowville formation, the Hungry Hollow mbr. of the Widder formation, and the Mahantango formation. Below are a couple of specimens that come from the Windom shale mbr. of the Moscow formation at Deep Springs Rd., NY.

Specimen #1 - has a flattened (crushed) brachial valve
Anterior
Pedicle valve
Posterior
Left profile - Here you can see that the pedicle valve is in good condition but the brachial valve has been crushed. Normally the brachial valve in a M. audaculus should be flat to slightly convex.

This is a chunk of rock from the Deep Springs Rd. site that has multiple impression and valves of M. audaculus. I have to wonder if this is the remains of a small colony that was swept up in a storm or just a grouping of shells that were winnowed by currents.

This specimen was found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.)

Friday, May 22, 2020

Grammysia bisulcata pelecypod from the Moscow formation

I looked back through my blog posts and am surprised that I have not yet featured this next fossil. It's Grammysia bisulcata and this specimen comes from the Windom shale.  It's a single right valve which shows the oval shape well. The other defining features are the widely spaced, concentric ridges and a wide furrow that extends from the umbo to the margin.  It's this furrow that distinguishes this species from Grammysioidea arcuata.




I thought I'd found specimens of this species in my local Mahantango formation rocks but I can't find a blog post for it. I will have to dig through my boxes and see if I can't rectify that.

This specimen was found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.)

Wednesday, May 20, 2020

Bellerophon pelops? gastropod from the Moscow formation

This crushed gastropod fossil looks similar to Retispira leda but the central rib is not decorated and there is no cross hatching on the rest of the shell. I could not find anything that matched this fossil in Karl Wilson's "Field Guide to the Devonian Fossils of New York" book so I went back to the bible for New York Devonian fossils, James Hall's "Palaeontology of New York".  There I found a description and plate for a species call Bellerophon pelops that looked like the fossil below.  R. leda is in the same family and B. pelpos (Bellerophontoidea) so it's no surprise the two look similar.


Ventral view - The only part of the shell this fossil is missing is the wide "skirt" that Bellerophontoidea have around the apeture. The specimen likely was found loose and had broken out of the rock.
Left profile
You can see the rest of the shell as it curves back and coils.
Anterior view
Right profile

This specimen was found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.) 

Monday, May 18, 2020

Retispira leda gastropod from the Moscow formation

Retispira leda is a Bellerphonid type gastropod that had a large, conispiraled shell with a wide flaring "skirt" at the front aperture of the shell. The shell must have been thin walled as I most often find it crushed nearly flat.  The key features that help to ID this fossil is the central rib that shows concentric, back curved growth lines. That and the cross hatching present on the rest of the shell, the results of linear striae running along the direction of the shells growth crossing concentric growth lines. The first specimen below has some of the flaring aperture intact while the second does not.

Specimen #1 - ventral view
 Dorsal view - at the top of the specimen you can just see the shell as it curves over the edge and continues spiraling under itself.
 This view shows you how flat this once bulbous shell looks now.

Specimen #2  - ventral view

Dorsal view - this has less matrix obscuring the coil
 A view of the now squished shell from the side.

These specimens were found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.)  

Saturday, May 16, 2020

Modiomorpha mytilodies pelecypod from the Moscow formation

Among the most common pelecypods that can be found in the Moscow formations is Modiomorpha mytilodies. It's an oval shaped shell with the anterior smaller than the posterior. The surface of the shell is covered with broad, undulating concentric growth lines.

Specimen #1 is a loose cast of the shell that is compressed to nearly flat

Left valve
Right valve
A view of the fossil profile from the ventral margin

Specimen #2 - isolated right valve


Specimen #3 - isolated left valve

Specimen #4 - Another loose cast but it's slightly deformed such that the right valve is partially folded over along the dorsal margin

Left valve
Right valve

These specimens were found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.)  

Thursday, May 14, 2020

Greenops sp. trilobites from the Moscow formation

Greenops sp. is a commonly found trilobite at Deep Springs Rd. and I have a number of specimens. I have left the ID at the generic level as I need to study the features that differentiate the species from one another a little more.

For example, here is a partial specimen that I found but the eyes are missing, the pygidium is tucked under the thorax, and the genal spines are missing or hidden. All of these features are needed to narrow the species down from a list of three or four.


One of the ways you can ID the species of a Greenops is by the configuration of the spines (also called pleural lappets) that extend from the pygidium. As pygidium are very common, one might be able to find a couple of species without having the full body fossil. In the case of the three specimens below, I believe all are Greenops boothi as they all have "short, rounded pleural lappets" (Wilson, 2014).

Specimen #1

Specimen #2

Specimen #3


* Wilson, Karl. (2014). Field Guide to the Devonian Fossils of New York. pg 204

These specimens were found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.)  

Tuesday, May 12, 2020

Tellinopsis subemarginata? pelecypod fossil from the Moscow formation

The fossil below is defying my attempts to identify it. It has a rectangular shaped shell with a rounded anterior and posterior. The umbo is near the middle but off center and angled to the anterior end. There are very fine radiating striae (ribs) and concentric growth lines as well. The specimen is about 2cm in length.

All of this leads me to think this is a specimen of Tellinopsis subemarginata. However, most specimens I have seen have the umbo a bit more towards the center of the shell and not angling towards any particular direction. I also don't see a distinct margin from the umbo to the posterior margin. Maybe this is just a representative of the species that is slightly different from the typical form. Maybe it's a juvenile specimen and has not grown enough to show all the features I expect.




This specimen was found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.) 

Sunday, May 10, 2020

Dipleura dekayi trilobite from the Moscow formation

Dipleura dekayi is the largest trilobite that I have found in middle Devonian aged rocks. At Deep Springs Road, in the Windom shale member of the Moscow formation, it is not uncommon to find dis-articulated pieces of this species.  Based on the characteristics of Dipleura I suspect it was a burrowing species more so than free swimming or walking on the surface of the sea bottom.  The exoskeleton is typically smooth and streamlined with no obvious spines. The only noticeable feature are small bumps or pits that cover the surface. These could have been sensory points with tiny hairs or other organic extension that allowed the animal to sense movement, electrical impulses, or perhaps smell it's prey.

Specimen #1 - An isolated cephalon which is mostly intact except for some distortion (likely incurred during burial and compression of the sediments) and one of the eyes missing.
You can see some of the small pinpoints that are present on the surface


Specimen #2 - An isolated pygidium that really shows off the pinpoint pits.




Specimen #3 - A dis-articulated, but complete exoskeleton. This is clearly a molt that was buried quickly as only the Cephalon has moved from it's original position.


Check out this specimen from the Mahantango formation (scroll to the bottom of the post) that shows only the cast of the exoskeleton. You can see the pits that are preserved on the above specimens are merely small columns or bumps. This is what leads me to believe there was some sort of organic connection from the soft body of the trilobite.

Another nice pygidium from the Windom shale that I found at Penn Dixie can be seen here.

And here is a post of some specimens of Dipleura dekayi from the slightly older Panther Mountain formation of New York.

These specimens were found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.) 

Friday, May 8, 2020

Sulcoretipora incisurata bryozoan from the Moscow formation

I've found a few small specimens of the delicate bryozoan Sulcoretipora incisurata at Deep Springs Rd.  They are a flat genera of bryozoan that occasionally bifurcates. If these were present in the Windom shale then there was likely not very much turbulence in the water from waves or currents. This lends more evidence to the theory that sometimes the environment preserved in the Windom shale at this site was sometimes quiet enough for more delicate sessile animals thrive.





I've posted some samples from the similarly aged Mahantango formation before in this post.

A similar species, Sulcoretipora deissi, is found in the Silica shale.

These specimens were found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.) 

Wednesday, May 6, 2020

Cypricardella tenuistriata pelecypod from the Moscow formation

Today I have a complete specimen of the pelecypod Cypricardella tenuistriata to show off. It has both valves and is well articulated with out distortion. C. tenuistriata is a rectangular shaped shell with the anterior having a small rounded appearance and then a straight edge back to the umbo. The Posterior is largely rounded but boxy. There is a straight hinge line along the top margin of the shell while the bottom margin is broadly curved. the surface of the shell has a weak ridge extending from the umbo to the posterior margin and thin growth lines decorate the surface.

Right valve
Left valve
Top margin
Posterior
Anterior
Bottom margin
A closer view of the right valve. You can see the concentric growth lines along with what looks like   borings of the shell by some creature. Perhaps a sponge or worm?

Compare this specimen to one from the (older) Panther Mountain formation.  Or this one from the Moscow formation along the Lake Erie shoreline.

This specimen was found at a borrow pit on Deep Springs Road in Madison County, NY which exposes the Windom shale member of the Moscow formation (middle Devonian in age, Givetian stage.)