Thursday, February 19, 2015

Atactotoechus fruiticosus bryozoan from the Moscow Formation

I found two little "stumps" of a bryozoan at the Deep Springs Rd. quarry in Madison County, NY. There is not too much to examine as they are fairly small but they resemble the species Atactotoechus fruiticosus. It is interesting to find these specimens as small, individual colonies and not larger, branching versions.

This first specimen is a thick, finger like piece with small monticules on the surface. The next few pictures will show different angles of it but this appears to be a single mound and was not broken off from a larger piece.

The second piece is a very small button like mound. It reminds me of Prasapora from the Ordovician.

This is the bottom of the specimen. I need to clean it off a little better to see if there is any evidence of what it attached to when it started to grow.
Top of the specimen

I have found Atactotoechus fruiticosus before in the Moscow formation at Lake Erie near 18 Mile Creek (Hamburg, NY) in the Wanakah shale of the Ludlowville formation.

Tuesday, February 17, 2015

Evidence of post mortem activity in fossil Pelecypod shells from the Panther Mountain formation

Once a hard shelled animal dies it's shell often lies around on top of the muddy bottom until it gets buried. While it is exposed it provides a hard surface for many other encrusting animals that otherwise would not be able to establish themselves. Today I have two examples of trace fossils that were left on the interior surfaces of pelecypod shells from the Devonian aged Panther Mountain formation in NY.

First up is this shell which may be an Actinodesma erectum or another species. It's hard to say for sure because along the hingeline only the wing is visible and not the ear. But that is not why I kept the piece. What caught my eye are the spider like trails that criss cross the fossil.
It's important to remember that the fossil is not composed of shell material (actual, remineralized or replace). Instead it is a cast that shows the interior surface of the shell. If it were a mold the shell would be concave and not convex like this specimen.  Getting back to the fossil, a closer look reveals what looks like cracks in the surface (which was my initial reaction). I think there is a better explanation though. These lines all join together and are sinuous in places and they also have differences in depth and width. Perhaps they are evidence of worm tubes or bryozoans that colonized the interior surface of the shell while it was exposed. It could also be evidence of a type of sponge that bored into shells and used the calcium carbonate to build it's skeleton.
 Then, off to the left side, I noticed another pattern. This one looks like a bursting firework or a flower like a Dahlia.
 A closer view shows a clear pattern and I think it is of a species of bryozoan called Paleschara incrustans. Interestingly, it appears to have over grown over one of the sinuous lines implying it colonized the shell later before it ultimately became buried.

 Another pelecypod fossil from the same locality is shown below and this one has multiple, straight and wide traces on it. 

To me these look very much like a boring clam or sponge that was digging a home within the shell of the expired clam.

Both specimens come from the Panther Mountain formation (Devonian, Givetian stage) at Cole Hill Rd. quarry in Madison county, NY.

Sunday, February 15, 2015

Hallotheca aclis hyolith from the Moscow Formation

Hyoliths are enigmatic creatures that existed from the Cambrian until the Permian. They have triangular shaped shells that are half moon shaped in cross section, an operculum that covered the head and two little horns, called helens, that protruded out from where the operculum and body met. I found a specimen of a Hyolith called Hallotheca aclis in Madison County, NY in the Moscow Formation (Devonian, Givetian stage). The view is of the ventral surface, or underside, of the shell and you can see the fine concentric growth lines.

The coolest part of this specimen is that the operculum is preserved as well and nearly articulated. It's rotated from the life position but the fact that it's even present is rare. This is the only specimen of the operculum that I've found.

The only other examples of this odd fossil that I've found have been from the Mahantango formation in PA of which a portion is roughly equivalent to the Moscow formation.

Friday, February 13, 2015

Modiomorpha and Grammysioidea pelecypods from the Moscow formation

Here are another group of bivalve fossils that I found at the Deep Springs Rd. Quarry in Madison County, NY. The rock exposed at the quarry is the Moscow formation (Devonian, Givetian stage).

The first fossil is a right valve from a Modiomorpha concentra showing the typical elongated oval shape with fine concentric growth lines on the surface of the shell.

This species is somewhat common and I've blogged about them being found in the Mahantango Formation Here and Here.

The next shell is squished horizontally so it's hard for me to ID for sure. The thick, wavy concentric folds on the surface (which do not represent individual growth lines) could be from two closely related species: Grammysia bisulcata and Grammysioidea arcuata. Both look overall the same but Grammysia bisulcata has a "belt" that runs from the beak of the shell across the folds down to the margin where the valves meet while Grammysioidea arcuata does not.

Right now I'm leaning towards Grammysioidea arcuata since I can't see a recognizable "belt".
As further illustration of this species, here is a different specimen that I found on the same trip. This one has been compressed flat but at least one of the valves (the right valve) is intact.

 I have collected G. arcuata before from the Moscow formation and also the Mahantango formation.

Wednesday, February 11, 2015

Goniatite fossil from the Moscow formation

This smooth, round snail like fossil is actually a cephalopod called a Gonaitite from the Moscow formation (Devonian, Givetian stage) that I found at a quarry off Deep Springs Rd. in Madison County, NY. They were precursors to ammonites and evolved from primitive bactritid type nautiloids. This specimen is a good size but does not preserve the sutures which would help to identify it. Tornoceras sp. is the most common genera in the Moscow formation and this could be a specimen of one. You can't see it in the pictures but there are a couple of thin cracks in the fossil that are filled with golden pyrite. It shows best when the rock is wet.

Monday, February 9, 2015

Camarotoechia sappho brachiopod from the Panther Mountain formation

I found this Camarotoechia sappho brachiopod at the Cole Hill Rd. locality in Madison County, NY. It comes from the Panther Mountain formation (Devonian, Givetian stage). I kept this specimen because it is a nice internal mold of the species whereas many of the other available specimens were just impressions in the rock and clustered tightly together. It's not perfect, however, there is a chip missing off the posterior that took the beak with it. Still it gives me a good representative specimen from the locality until I come across something better.

Saturday, February 7, 2015

Pseudoaviculopecten princeps pelecypod from the Moscow formation

Once you get to East-Central NY the Devonian rocks are less limy and more argillaceous and seem to preserve pelecypods better. Thus you get lucky and sometimes find both valves of a pelecypod laid out next to each other such as in this specimen. It's a Pseudoaviculopecten princeps and, while missing a bit of the left valve, is a nice specimen. Pseudoaviculopecten princeps can be identified by the rounded shape of the shell, whose width is greater than it's length, long hinge line with an extended ear off the posterior side as well as the crosshatching created by the raised radial ribs and concentric growth lines.

This specimen cam from the Moscow formation (Devonian, Givetian stage) and was found in a quarry off Deep Springs Rd. in Madison County, NY.

Thursday, February 5, 2015

Actinodesma erectum pelecypod from the Panther Mountain formation

This large steinkern, or cast, fossil is a pelecypod that I found at the Cole Hill locality in Madison County, NY. I've been reviewing some resources like "The Paleontology of New York" (James Hall, 1884) and "A field Guide to the Devonian Fossils of New York" (Karl Wilson, 2014) and I think that this fossil is of a Actinodesma erectum. It's a large, oval shaped steinkern with the body vertically aligned (or erect which is where it gets it name) which is unlike many other genera that are diagonally or horizontally angled. It would be nice if I'd found this piece with the accompanying mold from either side as that would have more detail. As it is, the fossil does not have the hinge line preserved which should be shorted than the body length with a wing on the right side and a short ear on the left side.

What does the fossil have that helps with the ID? Well, as I mentioned before, the body is vertically aligned and longer than wide as well as having an umbo that narrows slowly.
This anterior view shows that the left valve is somewhat convex while the right valve is only slightly convex.
Side view of the left side of the piece
Side view of the right side of the piece
A view of the right valve shows some faint, concentric growth lines

Due to the size and shape of the specimen I am keeping my initial ID of Actinodesma erectum. Another possible match could be Mytilarca oviformis, but that species has a much shorter hinge line, both valves are convex to the same degree as the other and the umbo is pointed. Actinodesma erectum (Conrad) Hall 1877 is the accepted name for this fossil which formerly was known as Avicula erecta Conrad 1842 & Glyptodesma erectum Hall 1883. Thanks to Karl Wilson for the taxonomy history lesson.

Tuesday, February 3, 2015

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.

Sunday, February 1, 2015

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.