Lichenalia torta? bryozoan from the Moscow formation of New York

Within the rocks of Fall Brook, near Geneseo, NY, sometimes you'll find odd dark colored fossils that look as though someone poured chocolate on the rock. I knew it was a fossil of some kind but getting a piece to reveal itself face up was not an easy task. So I kept a few pieces in the hopes that one day I would figure out what it could be. Now I may have an answer. While I was looking through the plates within the Paleontology of New York, volume  VI, I came across an illustration that appeared to match what I'd found.

Here is the specimen. You can see that it looks like the underside of a shelf fungus and most likely is the wrinkled epitheca of some genera of bryozoan or coral. The epitheca is the surface of the animal that was in contact with the underlying substrate that it laid upon. You won't see this if the animal encrusts a hard surface, such as a shell or rock, so this indicates that it was in contact with the seafloor itself (or possibly held above it) the undulating shape of the fossil makes me think it was laying on semi solidified mud.

Note near the bottom of the wrinkled area appears to be a Platyceras type gastropod shell. Perhaps that was the origin point for this colony?

It is a very thin fossil which could indicate that it grew very quickly, it grew up and out as the lower portions became smothered by sediment or the overall growth pattern was horizontally rather than vertically.

Since the fossil had a very unique appearance it stuck in my head. As I was looking through volume VI of the Paleontology of New York, I saw plate XV and recognized the illustrations as resembling what I'd found in Fall brook.

The description of the plate said they represent a bryozoan called  Lichenalia torta and had been found in the "Lower Pentamerus limestone" at Schoharie. This presents a problem as that particular horizon is considered part of the upper Silurian (Pridoli stage) while my specimen comes from the Moscow formation which is middle Devonian (Givetian stage). So while I may not be able to say for certain that what I found is indeed Lichenalia torta, It perhaps is a related species and I will have to wait until I can get a piece that shows the dorsal surface to determine the species.

Misc. fossil bits and pieces from the Bois D'Arc formation

To close out this series of posts featuring fossils I found in the Bois D'Arc formation of Oklahoma, I have a few pieces left from my finds that don't merit a full blog post entry so I'm consolidating them here. They are each interesting in their own right and deserve at least a mention.

This is a piece I kept as a curiosity. It appears to be the mold from some sort of epitheca that belongs to a coral (like Favosites conicus) or Bryozoan (like Lichenalia sp.).  There is some sort of discolored trace on part of it which could represent a worm tube that may have been pyritized during fossilization.  The question is, was it formed under the base in the sediment or on top of the base after it had flipped over?

Leon Thiesen told me a story about a dealer who used to collect lots of these and then pass them off as "Jellyfish". Leon himself was convinced until one day he found one of them after a bryozoan colony popped off the matrix. When he told the dealer about this their response was that they sold better as "Jellyfish" than bryozoan or coral impressions. It goes to show that you need to pay attention to what you are buying and not always take the word of the seller.


Next is this strange fossil that Leon gave me and told me was somewhat rare. He thinks it may be a bryozoan of some sort but he always finds them as flat, six lobed features in the rock. I think my specimen is missing a lobe.

Here are two single valves from a Rhipdomelloides oblata that I found and photographed after I had written up the blog post which featured articulated specimens. These show the interior details of each valve. I think they are from two separate individuals though.

And finally we have this odd crinoid holdfast that are often called "Chicken Feet" by the local collectors. This specimen is "curled up" but I saw other specimens in the field (on large rocks I could not bring back with me) that really did appear to resemble bird feet.

Whew! That was a long series of blog posts for a single locality. The Bois D'Arc formation is profusely fossiliferous and has a very wide variety of preserved animals. I'm pretty sure I found all the common species and a number of the lesser common ones too. While I didn't find many of the showy trilobites, I made out pretty well for surface collecting. I'm itching to go back again and trying to figure out how to fit in another visit between my other vacations.

I found the specimens shown on this page in the Bois d'Arc formation (Cravatt member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc and Haragan formations interfinger with each other and are roughly the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

Huntoniatonia sp. trilobite from the Bois D'Arc formation of Oklahoma

From my experience collecting in the Bois D'Arc formation, I think that Huntoniatonia sp. (also sometimes called Huntonia) trilobites are possibly the most common trilobite to be found. I'm referring to the isolated parts of the trilobite not whole specimens. While there were a large number of whole Paciphacops sp. and Kaniops sp. fossils that I found I think I came across more detached pygidiums and cephalopns of Huntoniatonia sp. than anything else.

I did find a few whole specimens but none are in really good condition. This one is slightly enrolled and little warped.

Here is one still in the matrix (it was about two inches long) but it was lying exposed to the elements and thus has some missing shell.

Another one in the matrix that is partially enrolled. The pygidium and thorax are visible on the one side while the other side shows the front edge of the cephalon and a Phacopid trilobite.

Then I have some cephalon and pygidium pieces like this one from a Huntoniatonia huntonensis based on the shape of the spine extending from the cephalic margin.

A view of the eyes of the specimen.

This is a completely different specimen half embedded in the rock with just one eye poking out.

Finally we have a couple of pygidiums from two different specimens that show the size differences. Some of the Huntoniatonia got really big!

George Hansen's wonderful website indicates that there are at least three species of Huntoniatonia that are found in the Haragan and Bois D'Arc formations.  The main differences are the size and length of the spines that extend from the tip of the pygidium and cephalon.

Kettneraspis sp. trilobite from the Bois D'Arc formation of Oklahoma

One of the spinier trilobites that can be found in the Bois D'Arc formation is Kettneraspis sp. it is usually a small fossil and it is best if you find it just peeking out from the rock. I found two nearly complete specimens while searching last August and some disarticulated pieces as well.

This is the first articulated specimen. It is about 75% there but the delicate spines are all weathered away and the left free cheek of the cephalon is missing. It's not bad for a surface find as most of the really nice prepped specimens are found by splitting the rock and looking for the outline.

Here is an isolated free cheek which shows the short spines that are on the lateral border of the cephalon.

I did find one really nice specimen but the rock it was on was very fractured and I didn't think I would be able to either get it home without further damage or repair it. Lucky for me Leon took a look at it and thought it could be saved. He wrapped it up in aluminum foil and took it back with him. A few weeks later he messaged me and told me that he'd been able to save it and it turned out to be a pretty nice specimen. Some of the spines are broken or missing and the cephalon has been compressed but it appears to be 95% complete.

The most common species found is  Kettneraspis williamsi but Leon told me that my fossil was an undescribed species. That may be because the specimen was incomplete or warped such that ID was difficult.

I found the specimens shown on this page in the Bois d'Arc formation (Cravatt member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc and Haragan formations interfinger with each other and are roughly the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

Cordania falcata trilobite from the Bois D'Arc formation of Oklahoma

Cordania falcata is a small trilobite and is uncommon in the Bois D'Arc formation. I found two examples that were prone and mostly complete, but neither were attached to matrix. Below is the better specimen of the two. It is about 95% complete and is missing a portion of the right genal spine. The trilobite itself is nearly oval shaped with a large rounded cephalon that typically has long genal spines that extend nearly the length of the thorax and pygidium. There is a small glabella with one furrow. The eyes are small, holochroal and slightly raised. The specimen below need to have some prep work done to expose the rest of the trilobite but should make for a nice example.

I found the specimen shown on this page in the Bois d'Arc formation (Cravatt member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc and Haragan formations interfinger with each other and are roughly the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

Reference: "Trilobites of the Haragan, Bois D'Arc and Frisco Formations (Early Devonian) Arbuckle Mountains Region, Oklahoma" 1977  K.S.W. Campbell, Oklahoma Geological Survey, Bulletin 123,  pg. 22, pl.5, fig 1-4

Phacopid type trilobites from the Bois D'Arc formation of Oklahoma

Trilobites are very common in the Bois D'Arc formation and several species can be found. There are two or three different phacopid type trilobites that I am aware of but to ID them you need to examine the eyes and cephalon. A good resource for help is George P. Hanson's book, "Trilobites of Black Cat Mountain" available on his website.  Below are some of the specimens I've found that are still encased in matrix which makes identifying some of them a bit more difficult.

Specimen #1 - Partially enrolled but with most of the cephalon hidden.

Specimen #2 - Enrolled but one of the eyes is visible. I think this is a Kainops raymondi but I need to see more details to be certain.

Specimen #3 is mostly free of matrix but the glabella is still mostly obscured. One of the eyes is visible and leads me to believe that this is a Paciphacops campbelli.

Here are some nicely prepped specimens from the Haragan formation, which were labelled as Paciphacops logani, that I blogged about a couple of years ago.

I found the specimens shown on this page in the Bois d'Arc formation (Cravatt member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc and Haragan formations interfinger with each other and are roughly the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.