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

Specimen #2 dorsal surface

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
Pedicle valve (the broken section does not help with the ID)
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).

Tuesday, August 18, 2020

Brachiopods and Worm tube on a Pelecypod from the Jeffersonville limestone

Multispecies specimens are always cool to collect. Sometimes it is just bedrock with a hash of many different species, other times it is a potential example of how life lived. The example below, from the Jeffersonville limestone, is in the latter category. It's a large unknown pelecypod shell that has a couple of brachiopods and a possible worm tube growing on the surface. 

The specimen

There is not enough of the pelecypod visible it ID it 100% but it could be related to Actinopteria sp. or Cornellites sp.  You can see at least three spirifirid type brachiopods that appear to be attached to the shell in life position.

I believe that the brachiopods are juvenile Mediospirifer audaculus based on the shape of their shells and how they are positioned on the pelecypod. M. audaculus has a flat to slightly sloping interarea and this is how I would expect it would look when laying flat.

Also on this specimen is what appears to be a worm tube, or possibly a very large Tentaculites sp.  If it is a worm then it might be Cornulites sp.

All in all, this is one of my favorite specimens from the Jeffersonville limestone and was collected on my first trip to the Louisville area back in 2007.

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

Sunday, August 16, 2020

Two pelecypods from the Jeffersonville limestone

I have very few good Pelecypod fossils from the Jeffersonville formation. I have been fortunate to find a number of examples of Paracyclas sp. (as shown in this prior post) but the two specimens below do not fit that genera.

The first specimen is somewhat rough but recognizable as a pelecypod. There are two valves, the shell is oval in shape, and there is evidence of the hinge line at the rear of the shell. Faint concentric growth lines are visible on the surface portions of both shells but the preservation of the shells is not so good at preserving the upper parts of the shell such as the umbo. If I were to guess, this could be an example of Modiomorpha sp. which is very common in the Devonian, but there is not enough detail for me to be sure.

Right valve
Left valve
Dorsal margin.  If this were an external cast rather than internal cast you would not be able to see the raised ridge like seam between the valves.

Ventral margin

Specimen #2 is a single, partial valve impression. It is notable for the radiating ribs that extend from where the beak would be.  Due to the angle of the ribs, and overall shape of the shell I think this is a genera from the subclass Pteriomorpha, order Pectinoidea. Perhaps Actinopteria sp. which is a very common genus in the Devonian.

I found these two specimens near Lousiville, KY and believe they come from the Jeffersonville Limestone, dated to the Devonian period (Eifelian stage).

Friday, August 14, 2020

Dolatocrinus sp. crinoid stems from the Jeffersonville limestone

It is rare that you can ID a loose crinoid stem segment to the genus it is from but some forms are very distinct. Today's example of that are some stem sections from the crinoid Doloatocrius sp.  What makes the stems unique are periodic growths that form a wider ring than the rest of the stem, and also have vertical extrusions at 120 degree intervals. The extrusions look a little like "fins"

The specimens shown below were sent to me as part of an trade with Mike P. and come from the Jeffersonville limestone near Louisville, KY.  I did some research and cannot find any examples on the internet that show these stems in life position with a calyx attached. Also, in one of my previous blog entries I have a note with similar specimens found in Arkona, Canada that they belong to Megistocrinus sp. crinoids. That note may or may not be correct as I have seen pictures of stems attached to Megistocrinus nodosus calyx that do not show the "wing" like growths, just the thicker ring.

So for now I will keep the current label of Doloatocrius sp. until I can positively confirm otherwise.

Specimen #1

Specimen #2

Specimen #3

I received these specimens in an trade with Mike P. and they come from the Jeffersonville Limestone  near Louisville, KY and is dated to the Devonian period (Eifelian stage).

Thursday, August 13, 2020

Mound like Bryozoan from the Speed Limestone

I've found a few specimens of what appears to be a mounding Bryozoan that lived during the Devonian period during collecting trips to the Louisville, KY area. I've also received specimens from Mike P. via exchanges and he has them labelled as "Eridotrypa sp. from the Speed limestone".  The Speed limestone is a member of the Silver Creek formation (or North Vernon/Sellersburg limestone depending on the resource you look at) and is above the Jeffersonville limestone. 

I am unsure of the actual ID for these specimens as Eridotrypa is a genus known from the Ordovician and Silurian. I believe this is an example of an order Trepostomata type bryozoan (as is Eridotrypa) but the preservation is not good enough to really narrow the ID.  I'd suggest that an ID of Monotrypa sp. (which forms hemispherical colonies with flat bases and is known from the lower to middle Devonian of New York) would be more appropriate for the age of the specimens but for now they will have a question mark on my labels.

All the specimens I have are very light with some clearly being hollow as a rattling can be heard inside when turned.  It is my interpretation that these are partially preserved examples with the exterior being the most extensively replaced. These likely represent casts of the actual calcitic fossils that dissolved away during the silicification process. Since surface details are lacking, the original skeletons could also have been tumbled on the seafloor prior to fossilization.

A clutch of specimens that all show similar features

Specimen #1 - side view

Dorsal surface of the specimen showing the small corallites

Another side view that shows the layering and cells of the colony

Bottom of the specimen which has features that could either be from growth over a non level surface, or dissolution features prior to silicification of the fossil.

Specimen #2

Specimen #3

I received these specimens via trade. They come from a quarry in Clark County, Indiana which is near Louisville, KY. The fossils are dated (roughly) to the middle Devonian (Givetian stage).