Dry Dredgers Field Trip
May 24
, 2014
Ponderosa Ranch, Ohio
Bellevue and Corryville Formations

Photos and words by Bill Heimbrock

The Dry Dredgers returned to a couple of popular sites in Ohio east of Cincinnati. The sites were nicknamed "Ponderosa Ramch" because the Bellevue Formation exposed on both sites are loaded with a bonanza of the brachiopods Vinlandostrophia ponderosa and Rafinesquina ponderosa. Both sites are road cuts, not really a ranch or farm.  We last visited there in 2009.

These sites also expose the bottom of the Corryville Formation, which is famous for lots of unusual and collectable fossils, such as Edrioasteroids, a type of echinoderm.


Here are some photos of the Dry Dredgers collecting at the first stop.


The second stop was pretty much just like the first stop, but less picked-over and smaller and kind of overgrown with weeds.


Fossils Found That Day


Probably the most interesting trilobite find was at the second site. It was a glabella what is probably the trilobite Amphilichas sp..

The next most interesting trilobite was this inverted, prone Flexicalymene sp. (Site 1).

Other fragments of Flexi's were found too, such as this thorax (Site 1).

The only other type of trilobite found that day was fragments of Isotelus sp. (next 4 pics). These first 2 pictures are from the pygidium (tail).


On every field trip to this site there has been at least one find of an Edrioasteroid. On this site, the Edrios are always partials. Most of the time, these are found on site #2. This time, the only Edrio was found on Site 1. It was very tiny - only about 5 mm. in diameter.


The best find was a couple of slabs of crinoids which include calyxes. One of the slabs is pictured below.  They appear to be Pycnocrinus dyeri (next 3 pics).

Crinoid stems were also found loose on the ground.

In addition to calyxes and stems, crinoid holdfasts were found. Here's an interesting one. It's a holdfast of the crinoid Anomalocrinus sp.


In the Corryville Formation and in the piles below those layers, a unique species of brahiopod is found - Rafinequina nasuta. This species is distinguished from other Rafinesquina species by a more triangular profile and a slight bump on the top edge. (next 2 pics).

The more common variety of this brachiopod we found on both sites was Rafinesquina ponderosa. (next 3 pics)

On the surface of these Rafinesquina, we found lots of the inarticulate brachiopod,  Petrocrania scabiosa. (next 4 pics)

Here's an uncommon collectable item. These are Petrocrania scabiosa that are free from the surface to which they originally attached. Interesting.

The other brachiopod for which the "Ponderosa Ranch" was named is Vinlandostrophia ponderosa. We did not find a bonanza of these brachiopods this time. But good numbers were taken home by all. (next 4 pics).

Also in abundance was the smaller cousin of the P. ponderosa, named Vinlandostrophia cypha. (next 3 pics)

Also common was the sometimes beautiful, but often broken or distorted brachiopod Hebertella occidentalis. (next 3 pics)



Bryozoans are abundant throughout the Cincinnatian. But there are many species and so they are just as collectable as other fossils. We found numerous Parvohallopora ramosa, amateurs can identify it by their raised monticules. (next 2 pics) 

There were also lots of ramose (branching) bryozoans on slabs.

Many of the massive trepostomate bryozoans had strange holes or borings in their surface called Trypanites. These are not the holes in which the bryozoan polyps lived. They were animals attaching themselves to the bryozoan colony, perhaps to share the bryozoans' food source.  (next 4 pics)

Another type of bryozoan we found were encrusters. Some of the brachiopods had a chain-like structure on their surface. These were cyclostomate bryozoans. (2 pics)


Both of these sites were great site for finding straight-shelled nautiloid cephalopods. Almost all were internal molds. These were one of the major predators of the late Ordovician seas 440 million years ago. (next 4 pics)

Pelecypods (bivalves/clams)

Clams are great! Whether you eat them fresh or collect them when they have fossilized, many Dredgers have a deep appreciation for these bivalve mollusks.   

Most Ordovician clams were preserved as internal molds with no external shell features preserved. A variety of clam we found that did have the shell surface features preserved is Caritodens sp.. (next 2 pics)

Here is a collection of some of the clams we found that were internal molds. Without the shell, it's hard to tell what species they were.

Gastropods (snails)

Snails are also one of those great mollusks. There are lots of species to collect. But often, identification to the species is difficult because there are so many types that can be found in the Cincinnatian Series. An easy one from this trip to identify was Cyclonema sp. (next 2 pics).

This next gastropod is probably Trochonema sp. but might be Lophospira sp..


Ichnofossils (Trace Fossils)

We didn't find as many trace fossils as we would if we were in the Kope or Fairview formations, but here is one of the interesting ones we did find. It looks like trilobite burrows on a slab. In this case, the slab is bottom side up and the burrows are represented by the mud that filled them in.

Worm Tubes

Occasionally we found brachiopods, such as this Rafinesquina sp. that have Cornulites sp. worm tubes attached to the feeding edge of the brachiopods. It is thought the worms position themselves for optimal feeding of whatever the brachiopod is eating.

That's all for this field trip. Hope you enjoyed it. Join us for our field trip to the Penn Dixie site in New York State and the Ridgemount Quarry in Ontario, Canada. (photos not yet available).

Now let's see pictures of our June 2014 field trip to Penn Dixie and Ridgemount Quarry.

See photos of our previous trips to the Ponderosa Ranch.


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