Dry Dredgers Field Trip
April 26, 2008
Ohio Ponderosa Ranch

In April, the Dry Dredgers continued their series of field trips that have not been visited in a while. Our destination is a pair of road cuts exposing the Bellevue and Corryville Formations. We have last visited this site in March 2001.

The attraction for this field trip is that these road cuts are rich in the large Ordovician Brachiopod, Vinlandostrophia ponderosa. Everybody found enough that day to make them happy. 

The day began with rain overnight, which seems to be a theme these days. The midwest has been having more than their share of rain. At least for fossil hunting, it's been a good thing
IMGP1487.jpg IMGP1492.jpg IMGP1503.jpgIMGP1514.jpgIMGP1521.jpg IMGP1526.jpgIMGP1531.jpg IMGP1535.jpg  

Alycia Stigall, of Ohio University, was the guest presenter at our April field trip. And since the field trip is the morning after the meeting and several of her grad students are studying the Upper Ordovician formations, it was very timely that they were able to join us on the field trip!
It was great meeting each of them. They helped us with the identification of the layers and we helped them locate the best fossil sites for their studies.


David had to point out that Bob and Taylor were sitting on a pile of rocks that is about to become a bigger pile of rocks, one of our continuing hazards as we collect fossils on road cuts.

IMGP1606.jpg IMGP1609.jpg
IMGP1545.jpgIMGP1601.jpgIMGP1622.jpg IMGP1625.jpg  

IMGP1700.jpg IMGP1707.jpg

Fossils Found That Day


Naturally some of the best finds that day were whole Flexicalymene meeki trilobites.

DSC0115.jpg DSC0124.jpg IMGP1695.jpg IMGP1696.jpg IMGP1687.jpg

One of the graduate students visiting from Ohio University, found that really nice double Rusophycus. These are trilobite burrows, likely to be made by Flexicalymene meeki.

Some of the Flexicalymene trilobites found were found on the surface of rocks and could be whole underneath the rock.

Many of the rocks were nearly covered with trilobite parts. Here's one rock with Flexicalymene parts, denoted in red and Isotelus parts, denoted in yellow.


One of the Echinoderms we found that day was this disarticulated Edrioasteriod. (This specimen was actually found at the third site).

The best Echinoderm found that day, was this nice crinoid calyx. I'm pretty sure this one is Pycnocrinus dyeri. (next 3 pics)
   IMGP1595.jpgIMGP1593.jpg IMGP1592.jpg

More common were articulated crinoid stems on the surface of rocks.


The brachiopods are what this site is known for. In particular, there were massive quantities of two brachs, Vinlandostrophia ponderosa (next pic) and Rafinesquina ponderosa (second pic). Thus the nickname for the site, the Ohio Ponderosa Ranch.

Many of these Vinlandostrophia are partially hollow and have been "geodized," that is to say, filled in with crystals.

There was another common species of Rafinesquina found that day. It's a species limited primarily to the Corryville formation, Rafinesquina nasuta (next 2 pics). They can be identified by the "nose" you can see pretty clearly in the next pic.

The Vinlandostrophia ponderosa were the most abundant. They loaded into layers of rock as is shown below.

Here's a typical bag of them as one member continues to collect.

Another species of Vinlandostrophia that was found is P. laticosta.

There were lots of examples of a common inarticulate brachiopod named Petrocrania scabiosa (2 pics). These appear as scabby patches on brachiopods, such as these Rafinesquina.
IMGP1990.jpg IMGP1994.jpg

Another common Brachiopod found was Hebertella occidentalis. Shown in the first pic are two Hebertellas with one Vinlandostrophia. The second picture is one Hebertella and the third shot shows a line of Hebertella.

Nautiloid Cephalopods

Quite a lot of straight shelled Nautiloid Cephalopods were found.

The one on the left in the next picture has a gastropod in side of it. The snail is probably of the genus, Paupospira. How it got there, I'm not sure. I think entered the living chamber of the empty Cephalopod shell.

IMGP1584.jpgIMGP1512.jpg  IMGP1680.jpg  IMGP1673.jpg IMGP1685.jpg IMGP1691.jpg      

Ichnofossils (Trace Fossils)

This is a really interesting trace fossil. It's a burrow of some kind. The fact that it is split down the middle  makes you think it's a trilobite burrow. Several rocks with this trace were found in the same spot coming out of the same layer on the third site.
IMGP1999.jpg IMGP2003.jpg  

This next fossil is interesting because the rusty material appears to have bleeded into the surounding shale. These could be crinoid stems or they could be burrows.

Most of the trace fossils were burrows along the surface of the rocks, like the one below. Note the cross-crossing.

Pelecypods (Bivalves or Clams)

The sites for this month were also good sites for clams. Here are some of the internal molds of what is probably Ambonychia. (next 2 pics).

Here's a "black clam" that a member found. It has a slightly carbonized surface but is an internal mold. It could be a Modiolopsis.

This next clam has shell material fossilized as the brown coloring seen below. Because of this, we can have confidence that this is a Caritodens.

Gastropods (Snails)

Here's a very artsy rock, decorated with cross-sections of snails in the matrix.

Commonly found on these sites, were the Gastropods with external shell features, called Cyclonema.

This next gastropod, which is coiled inward, as apposed to spired, is either a Sinuites, or the monoplacophoran, Cytrolites.


As always, plenty of Bryozoans were available. Some of the larger chunky ones, as in the next two pictures, may be Heterotrypa subfrondosa

Another bulky Bryo found in good quantities was Monticulipora mammulata. This next pic is probably one of those.

That's it for this field trip. Now have a look at our 2008 trip to Aurora, North Carolina.

Back to Field Trip Index

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.