Friday, January 31, 2014

Leiopteria conradi & Actinopteria decussata pelecypods from the Windom shale

Two more pelecypods from the Windom Shale for your viewing pleasure. Both are a little fragmentary due to the poor preservation and unstable matrix. They are notable for their size as I do not often find large specimens as intact as these.

Actinopteria decussata, note the faint decoration still visible, highly oblique shell body and extended wing.

Leiopteria conradi, Note the lack of decoration (just growth lines) and less oblique shell body.

Both specimens were collected in Buffalo Creek near Marilla, NY from the Windom Shale mbr. of the Moscow Formation (Devonian, Givetian stage).

Wednesday, January 29, 2014

Pseudaviculopectin exacutus pelecypod from the Windom Shale

Pelecypods are usually not very well preserved in the Windom shale but the below specimen is an exception. It is a valve from a Pseudaviculopectin exacutus that still has some replaced shell material  present.

The calcite that replaced the shell is very thin and delicate and some of it was removed when I was lightly cleaning it with a toothbrush. I'm leaving it as it for now and will likely coat it with a thin layer of PaleoBond to help preserve it. The specimen was found at the Penn Dixie site in Blasdell, NY within the Bayview coral bed of the Windom shale (Devonian, Givetian stage) mbr. of the Moscow Formation.

Monday, January 27, 2014

Eridophyllum subcaespitosum coral from the Windom shale

As I was cleaning up some material that I'd found at the Penn Dixie site in Blasdell, NY, I noticed the below specimen. It appears to be a pair of Eridophyllum subcaespitosum corals that are showing the budding habit common to this species as a means of asexually reproducing (also called gemmation). The upper portions of the corals are missing but you can see the connection between the individual corallites.

Interesting to note is that the left most corallite budded twice at the same level (only the one bud was preserved in this specimen) and then the second corallite also budded twice (both are broken and not preserved with this specimen) once it reached a vertical state.

This specimen was collected from the Windom shale mbr. (Bayview coral bed most likely) of the Moscow formation which is Devonian (Givetian stage) in age.

Saturday, January 25, 2014

Hadrophyllum woodi coral from the Windom Shale

These next few specimens are of the small "button" coral Hadrophyllum woodi that were collected in the Windom shale mbr. of the Moscow Formation. They are identified by the very short corallite (sometimes with nearly no elevation) topped with coarse septae and no thecal cup.

Specimen #1, I need to clean out the remaining rock from between the septae but this specimen shows the rough arrangement well.

Specimen #2
Unlike Specimen #1, this specimen attached itself to the edge of a shell fragment.

Specimen #3 shows a taller corallum growth habit that I've seen in about 50% of the specimens I've collected from the Windom shale. The theory goes that these coral lived only slightly elevated above the sea floor and so would often be smothered when a current changed or a storm event occurred and new sediment was deposited into an area. The fact that this specimen shows a taller corallite with a growth direction change indicates that it lived longer than the other two specimens and survived at least one storm event.

All the specimens above were collected at the Penn Dixie site in Blasdell, New York. The Windom shale mbr. of the Moscow Formation occurs within the Devonian period, Givetian stage of New York.

Thursday, January 23, 2014

Amplexiphyllum hamiltoniae coral from the Windom Shale

The next most common coral to be found in the Wanakah/Windom shale is Amplexiphyllum hamiltoniae. This coral is most easily identified by it's length, consistently narrow diameter and tendency of the corallite to show bends. Unlike Stereolasma rectum, this coral seemed to grow higher from the sea floor and so would be subject to toppling by wave base or current action.

Specimen #1 is small but shows the consistent diameter growth pattern.

Specimen #2 is still in matrix and shows a particularly long specimen. This is often the best way to collect these corals as otherwise they are found as fragments within the loose shale as they erode out.

Specimen #3 is also preserved in the matrix but is not as photogenic as the previous specimens.

All three specimens shown were collected from the Windom shale mbr. of the Moscow Formation (Smoke Creek Trilobite bed most likely) at the Penn Dixie site in Blasdell, NY.  Both the Moscow formation and the Wanakah formation are Devonian (Givetian stage) in age.

Tuesday, January 21, 2014

Stereolasma rectum coral from western New York

Possibly the most common and easily recognized coral found in the middle Devonian rocks of western New York is Stereolasma rectum. This is a small, solitary horn coral identified by the typical "horn" shape with obvious septal grooves on the side of the corallite. It thrived in the limy mud that was prevalent at the time but didn't seem to grow very high above the sediment surface of the sea floor. The specimens below were collected from along Lake Erie and are from either the Wanakah Shale mbr. of the Ludlowville Fm. or the Windom Shale mbr. of the Moscow formation.

Specimen #1

Specimen #2

Often the calices of these corals are infilled with rock or crushed as on this specimen.

Specimen #3, Occasionally you will find a specimen where the thecal cup has been broken away and the septae are visible as in the below fossil. (This particular specimen was collected from the Ledyard shale mbr. of the Ludlowville Fm. near East Bethany, NY)

Sunday, January 19, 2014

Pleurodictyum americanum coral from the Wanakah Shale

There is a bed present within the Wanakah shale member of the Ludlowville formation (Devonian, Givetian stage) called the "Pleurodictyum bed". As may be guessed, the coral Pleurodictyum americanum is common within the layers of this zone. Below are a couple of examples that I found along the shore line of Lake Erie. They stand out for me because of the substrate they colonized.

Specimen #1 is narrow because it started on the shell of a Paleozygopleura sp. gastropod.

Specimen #2 chose a section of Sulcoretipora sp. bryozoan.

Since Pleurodictyum needed a hard substrate to cement itself to, it's not surprising to find skeletons of other animals being used.