The first week of Autumn brought overcast skies for our September field trip to this much loved road cut on a southeast Indiana byway. Rain has been scarce in the summer and early fall, which for most sites means it should be picked over with no new fossils weathering out. But this is a huge site with lots of great late Ordovician fossils (440 million years old). It was not picked over at all.
The site exposes part of the Arnheim Formation at the bottom, the entire Waynesville and Liberty Formations and at the top, the Lower Whitewater/Saluda Formations.
Arrivals started early. The announced start time was 11 am. One out-of-town member arrived at 7:30 AM and spent all day there. There were plenty of fossils for everyone. Other members arrived as late as 3 pm. Here are photos from 11 am to 3:30 pm.
Field trips are great times for just standing around and talking fossils. We share information about the sites we've visited and share what we've found. Here's a Dry Dredger who has spent the last year revisiting this particular Indiana road cut. He brought trays of fossil he had found on the site we were visiting today to help us locate these types of fossils. Thanks!
On this site, in a previous visit, was found a beautiful calyx
of the Crinoid Cupulocrinus
(Back and front in next two photos).
The arms of this and other Cincinnatian crinoids look like
groups of stems, but are actually arms and pinnuals. We should be on the lookout
for anything that looks like a group of crinoid stems.
And we had an opportunity to see an Ordovician Sea Star that
was found on this site.
What was found that day
Someone had dumped a bunch of non-Ordovician fossils from another area onto this site near the road. Perhaps they were giving their students a test on what belonged on the site and what did not. Or perhaps someone was just getting rid of their extra fossils and knew that placing them here, the fossil would surely find good homes. This site is frequented daily by fossil enthusiasts from around the country.
There were Mississippian crinoids spread all over the edge of the road. (Next 3 pics)
Other non-Ordovician fossils included this coral head that was
cut and polished on a couple of sides.
The next two pictures are of non-Ordovician brachiopods found
among the discarded items.
Now for the indigenous late Ordovician fossils we found that day! (You were waiting for this.)
The most interesting find was this fragment of an anal sac
from the calyx of the crinoid
But there were tons of crinoid stems.
One interesting find was this rock loaded with stems and a
smaller curved stem that was probably acting as a holdfast.
Trilobites Found That Day
Among the trilobite finds, the best was a HUGE Hypostome (mouth plate) from what must have been a HUGE Isotelus Trilobite. Shown in the second
picture below, the finder is included for scale. It was a big hit with everyone
there, as seen in the third photo. Nice find!!!
Other Isotelus fragments were found everywhere
on the site and everyone who recognized them picked up at least one decent
Trilobites were also found, as well as parts. The layer with all the tiny Flexicalymene
retrorsa minuens was still producing good quantities despite the lack of
Good numbers of the large solitary coral Grewingkia
were found in the upper ledges.
Additionally, the smaller attaching solitary coral,
Streptelasma were found attached to all kinds of things, as shown in the next
Another attaching coral found was Proterea richmondensis.
This is a colonial coral that often encrusts Brachiopods.
Most of the gastropods (snails) found were internal molds.
Even though most Pelecypods (clams) found were also internal
molds, many showed internal and external features of the valves (shells). In
this first example, the valves were preserved as a black film on the shale.
In another specimen, even the hinge teeth were preserved.
These are diagnostic for identifying the genera and species of the clam.
Sometimes the external features are preserved, as in this
example of what is probably Ambonychia.
This next specimen, however is just the broken off end of an
internal mold of a clam, showing the hinge and parts of both valves.
Good quantities of clam internal molds were found.
Nautiloid Cephalopods Found
To my knowledge, no one found any of the coiled and curved
Cephalopods for which this site is famous. All that was found is the "dirt
common" straight shelled variety. (next 3 pics)
Pyrite Nodules Found
A few examples of Pyrite iron on slabs of rock were found. You
could say these are not fossils, but in many cases, they started out as fossils
until the "fossil cancer" took over.
Inarticulate Brachiopods Found
Among the inarticulate Brachiopods found, was this beautiful
example of Trematis millepunctata.
Another inarticulate Brachiopod found was the very common, Petrocrania scabiosa.
Articulate Brachiopods Found
This particular site is rich with a large variety of
Brachiopod genera. This first picture shows a slab of a plentiful Sowerbyellid
Brachiopod called Eochonetes clarksvillensis.
The next really common Brach shown in the next to pictures is Lepidocyclus (Hiscobeccus) capax.
Here's a sampling of the "take home" from one
member, which contains mostly Rafinesquina
along with other types of fossils.
Plenty of Strophomena
were found, which are similar to Rafinesquina, but having the
pedicle opening facing the opposite way.
Less common, but still easy to find, were the Brachipod Hebertella occidentalis.
Similar to Hebertella is a brach called Glyptorthis insculpta.
found on this site just as is found on most of our fossil sites. (next 3 pics).
Among the many hard-to-identify species of Vinlandostrophia are
the ones shown in the next 2 pictures, Vinlandostrophia cypha. They
are distinguished by having one strong and two week plications in the sulcus, by
having at least 10 plications on either side of the sulcus and by the fact that
they are found as high up as the Liberty formation, which is where this one was
Also found were lots of these tiny brachipods, often cemented
together in clusters. They are called Zygospira.
As always, Bryozoans were
everywhere. Resting on the rock in the next picture is a branching (ramose)
Bryozoan. To determine the genus and species correctly requires special tools to
take thin sections and examine them with a microscope.
Also found were flat and/or round Bryozoans of all shapes.
That's all for this field trip. Join us for our October field trip to a Northern Kentucky Kope and Fairview site.
See photos of previous field trips to this Southeast Indiana fossil meca.
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