Devonochonetes scitulus brachiopod from the Ludlowville formation

As I mentioned in my last post, Chonetid type brachiopods are tough to get a good ID on unless you have the delicate spines that emerge from the valve hinge line preserved. I was pleased to find one of the shells I'd found from the Geer Rd. locality (Upper Ludlowville formation, Devonian, Givetian stage) was a Longispina mucronata and so went back through my other findings to see if I could find any more. Lucky for me there was another specimen with spines present.

On this chunk of rock are a few stray Chonetid brachiopods but the well preserved specimen in the center right has a spine or two preserved.

A closer view with my camera reveals a single spine on the right side of the shells hinge line that is poking out at an angle.

Like with the Longispina mucronata specimen, I took this one up to my microscope to get a better picture. There is a single well preserved spine and what looks like the base of another just to the left of it. Based on the angle and location of the spine I would say that this specimen is a Devononchonetes scitulus (which has three to six spines extending from the hinge line, at an angle away from the shell), my first truly confirmed specimen of this species!

Specimens, such as these from the Arkona and Widder formations, have a similar shell size and ornamentation, and I've referred to them as D. scitulus, but I've not found any with spines that would confirm my theory.

Longispina mucronata brachiopod from the Ludlowville formation

I picked up this slab of chonetid type brachiopods while visiting a small quarry off Geer Rd. in Madison County, NY. The rock found there is a portion of the Upper Ludlowville formation (Devonian, Givetian stage) which has these zones of shell "pavement". Most of the shells I can't really identify beyond "Chonetid type" because to distinguish between the genra you'd need to see if they had spines growing off the hinge line. As the spines are delicate they often get broken off before the shell gets buried.

I was happy enough with the slab as is but, as I looked at some of the individual shells more closely, I found one that appeared to have spines preserved. I always do a happy dance when this happens but especially so in this case because I was able to determine that the species is Longispina mucronata.

The slab

A close up view of the shell. You can see the horizontal spine poking out of the left side of the hinge line.

Not satisfied with just a close view from my camera I took the piece up to my microscope and took a picture there. Here is a much closer view of the spine and I was pleased to see two more parallel to it coming from points farther in along the hinge line.

I've annotated this version of the above picture with what I interpret are the spines in white and the shell outline in red.

I have found a shell that I've called Longispina before in the Mahantango Formation (Devonian, Givetian stage) of PA, but this specimen looks a little different.

I also have a specimen that is labelled as Longispina lissohybus from the Silica Shale (Devonian, Givetian stage) of OH, but there are no spines preserved on that specimen.

Possible Monoplacophoran fossil from the Ludlowville formation

Sometimes you make good finds not in the field but at home when you are sorting through your finds. The fossil below is such an example.When I picked it up I probably thought it was an inarticulate brachiopod but as I cleaned it up and looked more closely it seems to me that it might be something different. When you look at it in profile the very tip of the shell appears to point backwards rather than straight up. If this were an inarticulate brachiopod I would expect the tip to be straight or very muted. There also appears to be a hole in the tip of the shell which could indicate that the tip broke off or maybe it is supposed to be that way (anal opening?). My instincts are telling me this could be a Monoplacophoran which is a mollusk similar to a gastropod or snail but different enough to not be included with them. Still I am unsure as I can not find any information on Monoplacophorans being found within the Hamilton group.

I have found Monoplacophorans before but they came from the Ordovician of the Verulam formation.

Nucula bellistriata pelecypod from the Ludlowville Fm.

It's rare to find whole Peleycpod shells with no distortion so I was quite pleased to find this Nucula bellistriata fossil. It comes from the upper Ludlowville Formation (Devonian, Givetain stage) at Geer Rd. Quarry in Madison County, NY. Both valves are present and it even appears that one valve may still be preserved with shell material. It would be nice if the hinge line were better exposed but there is a stubborn piece of rock still clinging to that section of the fossil.

Right valve

Anterior

Left valve

Left profile

Right profile

Posterior

The Devonian rocks of Madison county are closer in composition to those of my local Devonian rock, the Mahantango formation. I've found this same genera in the Mahantango with both valves but it is preserved as a internal steinkern (cast) with no external features.