Saturday, May 30, 2020

Spinocyrtia granulosa brachiopod from the Moscow formation

When I think of the brachiopod species Spinocyrtia granulosa the key features are the swept back and slightly recurved pedicle valve and the numerous small bumps or "spines" that can be found on the surface of the shell. This latter feature gives it a granular surface texture that gives the fossil it's specific name. 

Otherwise the shell looks similar to cousins Mediospirifer auducalus, and Mucrosprifier mucronautus with a rectangular wing shaped shell, slightly raised fold on the brachial valve and gentle "u" shaped sulcus on the pedicle valve. The specimens below come from the Windom Shale mbr. of the Moscow formation at Deep Springs Rd., NY.


Specimen #1 - A partial specimen that is missing the "wings" on each side of the central body. Brachial valve
Pedicle valve
Left profile
Posterior

Specimen #2 - A more intact specimen but it still has some damage. Some might argue that this might be a M. auducalus because of the rounded shell shape but I am calling it S. granulosa.
Anterior
Pedicle valve
Posterior
Another angle of the posterior
Right profile
Left profile

Specimen #3 - An isolated pedicle valve that has a nice bit of shell preserved with the granular surface.


 Compare these specimens to examples from the Mahantango formation, Hungry Hollow mbr. of the Widder formation, Morocco, Germany, and Spain.
 
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 28, 2020

Grammysioidea alveata pelecypod from the Moscow formation

One of the more common pelecypod fossils that can be found at the Deep Springs Rd. site is Grammysioidea alveata.  It's a subtriangular shell with well rounded posterior and anterior ends. The umbo is large and protruding. the surface of both valves have fine concentric growth lines but also widely spaced and prominent ridges.  This species is similar to Grammysioidea arcuata but is not as long.

Specimen #1 - Right valve
Left valve
Posterior profile - This fossil has been compressed nearly flat.

Specimen #2 - Right valve
Left valve
Anterior profile - Another specimen that has been crushed but this is not quite as bad as the prior specimen.

Specimen #3- Right valve. This specimen is less distorted than the prior two but still shows some compression along the dorsal to ventral axis
Left valve
Anterior profile
Ventral margin


I've found this species in the Mahantango formation of Pennsylvania as well.

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.)

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.)