Sunday, August 30, 2020

Thamnopytchia vermicula coral from the Jeffersonville formation

One of the more recognizable corals that I have found from the Jeffersonville formation is Thamnopytchia.  I've found it before in the similarly aged Mahantango formation (see link below) in Pennsylvania as well as in New York.  I identify this coral by the round, finger like growth, the regularly spaced corallites, and the surface ornamentation that looks like small dots or bumps.

Since this is from the Jeffersonville limestone I chose to refer to the book by Erwin Charles Stumm; "Silurian and Devonian Corals of the Falls of the Ohio". to help ID and found a possible match on page 70, plate 75, fig. 14-16, 18-20. to Trachypora vermicula.  Past research has informed me that the genus Trachypora is no longer used and is now called Thamnopytchia. Therefore I will label these specimens as Thamnopytchia vermicula.

This is the largest piece I have found to date and it shows evidence of preservation by the Beekite form of quartz.

Same specimen rotated 120 degrees from above photo

Same specimen rotated 120 degrees from above photo

A cross section through the coral that shows the "V" shaped corallites.

 

These next two specimens preserve some of the surface ornamentation of the coral.


Compare these specimens to some that I've collected from the Mahantango formation of Pennsylvania.

I collected these specimens from the Jeffersonville formation (Devonian, Eifelian stage) near Louisville, KY 

References: Stumm, E. C. (1964). Silurian and Devonian corals of the falls of the Ohio. New York: Geological Society of America.

Saturday, August 29, 2020

Hadrophyllum orbignyi coral from the Speed Limestone

 There is a small "button" coral that can be found in the Devonian rocks near Louisville, KY.  It's called Hadrophyllum orbignyi and is most commonly found in the Speed Limestone formation. I've received a number of specimens from my friend Mike P. that he has collected, but I have not found any myself.  

Below are two specimens that are preserved by quartz. The preservation process is not terribly good but the basic features of the coral are preserved. You can recognize the septa and fossula (the wider gap at 12 o'clock in the first specimen). Fossula is from the latin word for ditch or trench which is a good description of the feature in rugose corals.

I call these types of fossil coral "buttons" because they are small, round and have a flat profile.  Compare these to the species Microcyclus thedfordensis that is found in the Arkona formation of Canada.

 Specimen #1 dorsal surface

Ventral surface
Profile

Specimen #2 dorsal surface

Profile
Ventral surface
 

These specimens were found in Clark County, Indiana near Louisville, KY. They come from the Speed Limestone which is middle Devonian in age (Givetian stage). Thanks to Mike P. for the specimens!

Monday, August 24, 2020

Megastrophia concava brachiopod from the Jeffersonville formation

Among the largest brachiopods know is Megastrophia concava which is somewhat common in lower to middle Devonian aged rocks.  The shell is typically oval to rectangular in shape, has a convex pedicle valve, a convex brachial valve and a straight hinge line. It is a member of the order Strophomenida and is related to Strophomena, Leptanea, and others with a similar shell morphology.  This specimen is preserved by chert/beekite and only a partial internal/external cast of the pedicle valve is visible.

Pedicle valve
Anterior - most of the edges of the fossil near the margin show the exterior radial ribs.
Right profile
Posterior showing the internal cast where the muscles were attached (triangular shapes). The round bubbly shapes are Beekite which is a form of quartz.

I found this specimen near Lousiville, KY and believe it comes from the Jeffersonville Limestone, dated to the Devonian period (Eifelian stage).

Saturday, August 22, 2020

Possible Atrypidae type brachiopod from the Louisville formation

The single specimen below is the only one I have found from the sediments near Louisville. I believe that it is an member of the family Atrypidae and may in fact be a member of the genera Atrypa. It looks very similar with a rounded outline to the shell, a more deeply curved brachial valve than pedicle valve, and has radial ribs that look typical. However the anterior margin has a sulcus that is confined to the forward 1/3 of the two valves. It does not continue all the way to the beak on the pedicle valve.  I have seen examples of Atrypa with a similar feature but generally the pedicle valve is much flatter than in this specimen.

Brachial Valve
Anterior
Pedicle valve (the broken section does not help with the ID)
Posterior
Left profile
Right profile

This specimen was found in an area that had mixed residual soils from the Jeffersonville limestone (Devonian) and Louisville limestone (Silurian) formations near Louisville, KY.  Based on my experience with the preservation styles of the two formations, I think this came from the Lousiville limestone (Homerian to Gorstian stage of the Silurian).

Thursday, August 20, 2020

Fenestellid type bryozoans from the Jeffersonville formation

I have one example of Fenestellid type Bryozoans from the Jeffersonville formation. The specimen below has pieces of the fan like, lacy skeletons impressed on the chert.  Unfortunately the preservation is not fine enough to preserve enough of the zooids to try and ID to the generic level.




 
I found this specimen near Lousiville, KY and believe it comes from the Jeffersonville Limestone, dated to the Devonian period (Eifelian stage).