The weather held out for the Dry Dredgers that overcast spring morning. There had been plenty of rain, but none that day. March field trips are often "iffy", but the Dry Dredgers hold their field trips rain or shine.
The site we chose for the day was one that has been popular for decades, particularly in the spring, when the winter's freeze and thaws break down the shale into clay and expose high quality fossils of all kinds. The layers exposed are from the Kope (Latonia) Formation. So they are mostly shale, or mudstones, with occasional cycles of hard limestone rock the pros call carbonate facies. The site showed us most of the Southgate member of the Kope. I love the Southgate. We have had so much fun over the years collecting on these northern Kentucky road cuts. I hope the photos give you an idea of how we enjoy being out here.
Pictures of the site:
Fossils Found that day:
Best Find of the Day
The best find today was a nice piece of what I think is
colonial coral from the Kope Formation. Coral is rare, or at least uncommon, in
the Kope. Almost all the reef building animals were Bryozoans 450 Million Years
ago in our area. I'm not completely certain this is coral, though. The openings
have weak or no septa. (See second photo). In the Cincinnatian, unlike in the
Lexington layers to the south of us, the preservation is much better. There is
very little crystalization and mineralization. In any case, this is a great
The next great find by a young member. It's Bryozoan with borings of Catellocaula vallata.
This is thought to be a tunicate. It is bored into a Prasapora simulatrix
Bryozoan. (next 2 photos).
This site is famous for the
calyxes that can be found here. Here are some pictures of the calyxes
(head) found today. They are all from the crinoid,
No examples of the usual crinoid Cincinnaticrinus varibrachialus were found. They are probably more common than the ones we did find, but are smaller and harder to see.
Our field trip chair, Bob Bross, wanted us to find other types
of crinoids so badly that he presented his rendition of a crinoid by dipping a
weed in mud. Look familiar?
Other parts of crinoids were also found, such as this great
holdfast of the very large crinoid
Crinoid stems and stem columnals could be found everywhere.
They were on the surface of rocks, lining cephalopod in-fills as well as the
bottom of gutter casts. (next 3 pics).
It was also foretold at the meeting the night before that many
Nautiloid Cephalopods would be found. They were right. And the shell
preservation on many of these is excellent!.
Above photo by Marianne Shelton
Often, the center tube called the Siphuncle is broken open and
is often mistaken for a Sea Star arm.
Here's an interesting specimen. This is a fragment of a huge
Cephalopod that is encrusted with bryozoans.
Graptolites are very common on the shale surfaces of rocks at
this site. They appear mostly as black markings on the rocks.
Sometimes the Graptolites retain some of the 3 dimensional
features, as shown in the one found below.
The two types of trilobites found were Flexicalymene and Isotelus.
Some Flexi's were found whole.
photo by Marianne Shelton
While other Flexicalymene's were found as molted parts. Here's a pygidium (tail) in matrix (rock).
The burrows of Flexicalmene trilobites were also
found. In this form, they are called Rusophycus.
No whole Isotelus were found, but quite a few hypostomes (mouth plates) were found. (next 3
photo by Marianne Shelton
The shale layers of the Kope formation are not always
homogenous units of hard clay. There are often pockets of nodules, usually below
limestone layers. On some of these nodules, you can see encrusters like
bryozoans and crinoids. In the two examples below, no encrusters were found, but
the color of the nodules has changed and there may be surface evidence that
encrusters had been weathered off these specimens.
The Kope Formation has a number of mollusk layers that are
loaded with snails, clams and cephalopods. Most of these mollusks have excellent
shell preservation. Here's a sampling.
Some bryozoans we found had what appeared to be borings in them, such as the next specimen. It's possible this is Catellocaula vallata.
This bryozoan on a rock surface was preserved by iron pyrite
and other minerals.
A wide variety of bryozoans could be found on this site. The
one in the center of the next photo is
Worm Tubes Found
The tubes of annelid worms such as Cornulites were found loose on on rock surfaces, as shown in the next two photos. When found in rocks, they do not always show that in life their narrow end was attached to something. Occasionally, we find what may actually be a free-swimming animal, known as Tentaculites. The true nature of the animals that made the fossils Cornulites and Tentaculites are still being investigated and can still be considered problematica.
Trace Fossils Found (Ichnofossils)
Previous Trips to This Site
That's it for March 2009. Now lets look at April's field trip when the Dry Dredgers return to the Ohio Ponderosa Ranch.
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