Dry Dredgers Field Trip
Saturday, September 24, 2016
Northeastern Kentucky
Latonia (Kope) and Fairview Formations

It felt like late summer and the turnout was decent but not spectacular for being the first club field trip since June. Some of us visited this site in June when we hosted the Cincinnati Mini-Conference on Paleontology with the Fossil Project, which brought fossil clubs from around the country to collaborate with professional paleontologists and explore the rich stratigraphy of the Cincinnati area. In June, we spent three days fossil hunting and one day at the Geier Collections and Research Facility of the Cincinnati Museum Center.

But today it is all us. This is where beginners in fossil hunting get to try their hand under the guidance of experienced fossil collectors in finding and identifying Cincinnati fossils.

Fossils Found That Day

Best Finds of the Day

The "award" for the best find of the day goes to Christa for finding a couple of slabs of rock loaded with articulated stems and calyxes (crowns). The slabs contained a total of eleven calyxes that were visible with a strong possibility that more calyxes may be found under the surface of the rocks.

Here are photos of some of the eleven crinoid calyxes on those rock surfaces.

The next best find of the day was by Christa's husband, Matthew. He found a flattened Conularia including both the positive and negative impressions on a shale surface. (next 3 photos)

Ichnofossils (Trace Fossils)

We found some great trilobite trace fossils that day. This site was loaded with them, so it was easy.

These next three photos are of trilobite tracks called Cruziana. Looks at each and try to figure out what the trilobite was doing and where it was going.

On the slab pictured below there is an easy to identify Cruziana (trilobite track) in the center but the interesting one is in the upper portion of the photo. The multiple branching is typical of Arthrophycus, which is not always thought to be made by trilobites. This example does look like a trilobite running to catch something and retracting back to a safe place. Are there other explanations? Absolutely. Is this the right one? Possibly.

Here's another very tiny Cruziana (track) made by a very tiny trilobite.

This next trace fossil is pretty interesting. It may be a trilobite with each leg creating a trail or it could be something else? Perhaps the trilobite was moving fast through the water and dipped slightly into the mud, making this trace of its legs. Imagination is a wonderful thing. :-)

Here's a slab that is loaded with traces. The one I find interesting has a close-up in the second photo.

The trail in the above close-up may not be a trilobite, but what's going on with the trilobite glabella in the lower section of the photo? It appears to be pushed into a vertical position with a trace of the action left in the mud.

The below photo is a close-up of the trilobite glabella. Notice the furrow on the back side of the trilobite fragment. This sometimes indicates a back and forth motion. Was someone feeding on a dead trilobite?

As you have probably surmised by now, trace fossils require some imagination. Or imagination is required to consider them fossils. The photo below looks a bit like a trilobite Rusophycus, but may be something else.

Here is another slab loaded with trace fossils. These are hard to identify but are interesting sediment in-fills of burrows and tracks.

We found some traces fossil called Diplocraterion.  They are vertical worm borrows forming a "U" shape when seen from the side. From the top they look like "dumbells". (next 2 pics)

A special thanks to Dr. James Thomka for his helpful insights on the above trace fossils.

I'm not sure what made these burrows but they are some intriguing traces. (below)

The photo below appears to be a gutter cast.

This next slab contains the casts of a lot of tiny burrows. The two larger bulges might be casts of ripple marks in the Ordovician sea floor.

We found a couple of slabs on this site that were riddled with pockmarks. Upon closer examination, we could see they were the impressions of brachiopods with the concave side up. Some of the brachiopods were still in place to prove it! (next 2 pictures)

Here's an odd one. I think it's a bryozoan with a weird concentric indentation. Perhaps the indentation is the underside of an Anomalocrinus sp. holdfast. These crinoid holdfasts are often called "volcanoes" for their shape. In this case it's inverted.

More typically, indentations in bryozoans are assigned to Trypanites sp., such as the one below which was found that day.

This next slab has centimeter-sized ripple marks. These superficially resemble the markings on the new fossil code named "Godzillus."

Is this next slab a fossil? No. It's just the way shale breaks along or against the cleavage. Perhaps it's conchoidal, a breakage pattern more commonly found in slate and chert.

Trilobites

Unfortunately, no complete trilobites, prone or enrolled, were found that day. Only fragments. However, if the fossil collector had a hand lens, they could find parts of unusual or coveted trilobites. Such was this genal spine of a tiny spiny trilobite, probably Acidaspis cincinnatiensis.

In some layers on this site, a large number of trilobite fragments resulting from their molting process were found. These fragments are mostly from Flexicalymene sp. and Isotelus sp. (next 3 pics)

Nautiloid Cephalopods

The cephalopods we found in the Kope and Fairmount formations have a nice brown color to them that stands out from the color of the grey shale. Oddly, these orthocones (straight cone-shaped shells) appear flattened while the original shell was not. See the example below.

This is no mystery. Sediment filled the bottom half of these cephalopod shells but not the top half, causing the bottom half to be well preserved 450 million years later as calcite. We found a perfect textbook example shown below of where the bottom half of the shell was filled in.

As you can see in the photo above, the cephalopod had a perfectly round shell but calcite only replaced the outer edges and the sediment inside. Over time, most specimens wore down to have only the thick calcite infill. This explains the flattened shapes we often see.

Here's another example. It's a pair of straight-shelled nautiloid pointing in opposite directions, mostly preserved in that lovely brown calcite. In this case, the cavity where sediment did not fill has become a kind of geode with calcite crystals hanging from the "cavern" walls and ceiling. I apologize for not getting a close-up of this. 
.

Here are a few more cephalopods with brown calcite preservation.

And now found a very flattened nautiloid cephalopod with Spatiopora sp. growing on the surface. The puzzle becomes - what happened first, second and third?
1) The cephalopod was alive,
2) The cephalopod was encrusted by the bryozoan Spatiopora sp.
3) the cephalopod died and the shell was flattened.
Is that the correct order???

Crinoids

Not many crinoid calyxes (crowns) were found that day. Here's a partial calyx of what is probably Ectenocrinus simplex.

Mostly we found stems, some were articulated as seen on the slab below.

Brachiopods

Brachiopods were fairly common on the site. There were lots of species that could have been found but was not. This is probably because most of the brachiopods in the Kope and Fairview formations are very small and go unnoticed by the beginner.

One from the Fairview formation that someone found was Plectorthis sp. (below).

Oddly, only a few Vinlandostrophia sp. were found.

Here's a Rafinesquina sp. with a crinoid holdfast on it. The holdfast is of the type Lichenocrinus.

Rafinesquina are so abundant that the rocks are often paved in them.

Now we can move on to the somewhat less common brachiopods, the inarticulates. I found a nice pair of Trematis millipunctata.

Someone else found this interesting specimen of Petrocrania scabiosa. It's pictured below alongside two articulate brachiopod fragments on the right and bryozoans on the left.

Bryozoans

Probably the most sought-after bryozoan we found at this site was the one below - Escharopora falciformis.

Another bryozoan we found that is a must have for any collection of Cincinnatian fossils is Constellaria florida. (2 pics)

Here's a bryozoan identified as a type rather than a genus and species. It's a fenestrate bryozoan. On this one slab it was found on both the top surface and a split under surface. If asked for a species, I would say it's Chasmatopora sp. (2 pics)

Some bryozoan colonies begin encrusting a brachiopod and then grow to many times bigger than the brachiopod. (next 2 pics)

Other bryozoan colonies branch out as they grow , creating networks of branches (next 2 pics).

Here is a group shot of one member's trepostome bryozoan take-homes.

Gastropods (snails)

One of the most common snail fossils we found was Cyclonema sp., which has external shell feathers preserved in a brown calcite color.

An even more common gastropod are the internal molds of Hormotoma sp..

Pelecypods (clams)

We found a lot of impressions of clams on the surface of rocks. Many had a black film that may be what's left of the original aragonite shell.

Other clams we found were internal molds, like the one below. The only shell features on these area the hinge line and an occasional muscle scar.

That's all for the September 2016 field trip. Now let's see the pictures of the October 2016 field trip with the KPS.

Back to the Field Trip Index Page

Return to Dry Dredgers Home Page

The Dry Dredgers and individual contributors reserve the rights to all information, images, and content presented here. Permission to reproduce in any fashion, must be requested in writing to admin@drydredgers.org.
www.drydredgers.org is designed and maintained by Bill Heimbrock.