My last class at Wooster: Sedimentology & Stratigraphy in the Spring Semester of 2024

The delightful students above are shown on the last day of the Spring 2024 semester edition of the Sedimentology & Stratigraphy course. I’m retiring from the College of Wooster in August of 2024, so they are my final students. Thank you to Professor Greg Wiles for taking this group photo. It was an excellent class to end my 43-year teaching career at Wooster. They were enthusiastic, creative, smart, and curious. We met every Tuesday and Thursday at 8:00 am, and they never failed to be lively and engaged. I have been remarkably fortunate to have been able to teach generations of students like these. Here’s to their future success in whatever endeavors they choose to explore!

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The encrusters who went missing: A new paper on the taphonomy of bryozoans that encrusted brachiopods in the Late Ordovician of the Cincinnati region, USA

I’ve spent much of my career investigating marine sclerobionts through time. A sclerobiont is an organism that lives on or within a hard substrate. Among marine sclerobionts are oysters that encrust cephalopod shells, barnacles attached to boat hulls, and clams that bore into coral reef. My favorite historical examples are the sclerobiont communities inhabiting the abundant brachiopod shells in the Cincinnati Group (Upper Ordovician) of Ohio, Indiana and Kentucky. These diverse assemblages, like those on the brachiopod shell above, are fun to study because they record fossilized organisms in their original positions (in situ) on these hard substrates. This means we can plot out relative timing of community development by mapping overlapping encrusters and borings that cut through the resulting encruster stratigraphy.

But what if occasionally encrusters were removed from these assemblages without leaving any traces of their existence? This is the dilemma described in a new Historical Biology paper by myself and colleagues Caroline Buttler and Olev Vinn. Below is the abstract with some of the critical figures —

Abstract — The abundant shells and hardgrounds in the Cincinnatian Group (Upper Ordovician, Katian) of the upper midwestern United States were commonly encrusted and bored by a variety of organisms. Numerous studies of these sclerobiont communities have provided valuable data for models of ecological succession, symbiosis, space and food resource competition, and taphonomy. An underlying assumption of this work is that most of the skeletal encrusters have remained in place, firmly attached to their hard substrates. This is especially the case with the most common encrusters, thick trepostome bryozoan and cystoporate skeletons, on their most common substrates, flat strophomenide brachiopods. We present evidence here, though, that these bryozoans were often dislodged from their brachiopod hosts, leaving no evidence of their attachment other than horizontal borings in semi-relief from organisms that excavated tunnels (Trypanites and Palaeosabella) at the interface of the brachiopod shell and attaching bryozoan. Similar borings are found on the bases of dislodged bryozoans and in bryoimmured mollusc external moulds. These borings along the bryozoan attachment surfaces caution us that there are significant numbers of missing skeletal encrusters on these hard substrates.

Figure 1. External ventral valves of Cincinnatian strophomenide brachiopods showing Trypanites and Palaeosabella borings in semi-relief (‘unroofed’), location C/W-153 (A, B, E, F), and attachment surfaces (undersides) of trepostome bryozoans showing Trypanites and Palaeosabella borings in semi-relief (‘unfloored’), location C/W-148 (C, D). (A) Unroofed borings in a variety of directions in the brachiopod valve; specimen #CW153–1. (B) Unroofed borings perpendicular to the brachiopod commissure; specimen #CW153–2. (C) Mostly Palaeosabella borings distinguished by distal clavate terminations; specimen #CW148–1. (D) Mostly Trypanites borings with cylindrical forms; specimen #CW148–2. (E) External ventral valve; specimen #CW153–3. (F) Internal ventral valve; specimen #CW153–4.

Figure 2. Thin sections (A–E) Location C/W- 153 and acetate peel (F) Location C/W-148, perpendicular to brachiopod valves encrusted by bryozoans colonies, all extensively bored. (A) Borings infilled with dolomite rhombs (right) and calcite (left); specimen #CW153–5. (B) Borings infilled with micrite, some within brachiopod shell, and other cutting through shell and encrusting bryozoans; specimen #CW153–6. (C) Borings infilled with dolomite rhombs and micrite; specimen #CW153–5. (D) Borings showing two ghosts inside, suggesting that the soft-bodied organism was U-shaped along the axis of the boring; specimen #CW153–7. (E) Small boring within brachiopod shell infilled with calcite; specimen #CW153–7. (F) Brachiopod valve encrusted with a trepostome bryozoan with two cylindrical borings parallel to the shell: the one on the right cuts through the brachiopod and encrusting bryozoan; specimen #CW148–3.

Figure 3. Diagram showing the proposed process for forming unroofed borings in brachiopods and unfloored borings in encrusting bryozoans. (A) Cross-section of brachiopod valve with encrusting bryozoan attached; the borings are perpendicular to the cross-section plane; note borings that excavate both the brachiopod shell and the overlying encrusting bryozoan. (B) Same cross-section with the encrusting bryozoan detached, leaving unfloored borings in the bryozoan base and unroofed borings in the brachiopod valve.

The implications of this taphonomic process that can remove encrusting bryozoans from shelly substrates include the important reminder that critical information is always missing from our paleontological data sets. In this case even the simple observation that a particular fossil brachiopod is not encrusted does not mean it wasn’t previously encrusted before burial.

Reference cited:

Wilson, M.A., Buttler, C.J. and Vinn, O. 2024. Traces of missing encrusters: borings reveal sclerobiont taphonomy in the Upper Ordovician (Katian) of the Cincinnati region, USA. Historical Biology (in press).



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Geochemistry Adventure in a Flooded Killbuck Marsh

On Wednesday Dr. Matecha’s Geochemistry class took a trip out to Killbuck Marsh to collect water samples for a research project.

This week saw Ohio and Wooster especially inundated with heavy rain, which led to some very interesting conditions for the trip.

From the first sampling site the class could tell they would have to get creative. Flooded roads weren’t a deterrent for this class though! They embraced the challenge with their mud boots.

Dr. Matecha was contemplating whether the other sites would be accessible.

Students used their resources to collect samples, even from some harder to reach spots.

And sure enough, the next road was also flooded.

But once again this class marched out into the water undaunted.

Finally, an unflooded road! Though the channel here had flooded far beyond its normal banks.

Students were not impressed by the amount of trash people had been throwing into the marsh.

The area was so flooded that Savage Run creek couldn’t even be separated from the marsh anymore.

Despite the flooded road the class was able to approach the other side of the marsh to access some of the sampling sites.

One of the interesting locations was by a retired oil well, where students could smell gas.

Along Clark Rd. the channel had flooded over both walking paths that follow the channel.

A few of the most adventurous students got in a little over their heads, or should I say boots? Quite a few pairs of wet feet were had by the end of the day.

But as always this didn’t diminish the class’s spirit in the slightest.

In the end the class was able to collect a nice variety of samples, build their field skills, and had a fun day exploring Killbuck Marsh. We are excited to see what the chemistry of their water samples tells us about the marsh and local environment in the next few weeks. The class will be presenting their findings as part of their final project.






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An ancient name remembered

In the summer of 2018 I traveled to Wales for a conference in Cardiff. Immediately afterwards I visited my dear fiends Caroline and Tim Palmer in Aberystwyth, and they gave me a tour of Welsh sites they found particularly interesting. It was a spectacular trip, and I learned and saw so much.

One afternoon we visited a sixth century memorial stone in a field near the coastal village of Penbryn, western Wales. (The image above is from this site.) It is a micaceous ferruginous medium sandstone block about 1.4 meters high inscribed with “CORBALENGI IACIT ORDOVS”, which translates to: “Of Corbalengus (here) he lies, an Ordovician”. This carved stone is Celtic and one of the very few monuments mentioning the Ordovices tribe, which is the namesake for the Ordovician Period. Corbalengus is thus popularly known as the “Last of the Ordovicians”, or at least the last of the tribe for which there is any record.

Tim and I thought at the time that Corbalengus should be memorialized in the taxonomic record, recognizing the connection between the Ordovician Period and the vanished tribe for whom it is named. This year my Estonian, Russian and German colleagues and I had the opportunity to name a new species of Ordovician tubeworm as Conchicolites corbalengus Vinn, Wilson, Madison, Ernst and Toom 2024 (pictured below). Appropriately, it is from the Hirnantian Epoch at the end of the Ordovician.

Conchicolites corbalengus is from an abundant and diverse fauna of cornulitid tubeworms found in Estonia. These particular tubeworms appear to be dwarf forms compared to other varieties. These specimens also suggest that cornulitid tubeworms were little affected by the Late Ordovician extinctions. Our work here is part of a larger effort to describe the evolution and paleoecology of tubeworms through the Phanerozoic. They are excellent subjects for this kind of work because they have a moderate number of morphological features that are easily studied and assessed.

This story, though, is about the mysterious Corbalengus, for whom we have only a carved name on a lonely Welsh stone in a field. He must have had some notable reputation in life to merit the carving and erection of a monument, but we’re unlikely to ever know the details. But he had a name. One of my favorite childhood songs was Jim Croce’s 1973 hit “I Got a Name” —

Like the pine trees lining the winding road
I’ve got a name, I’ve got a name
Like the singin’ bird and the croakin’ toad
I’ve got a name, I’ve got a name

And I carry it with me like my daddy did
But I’m livin’ the dream that he kept hid

Corbalengus may not have been thrilled to be immortalized by an extinct and nearly-microscopic wormtube, but the fact that we know his name at all is a tribute to ancient stonework and the modern system of taxonomic records.


Vinn, O., Wilson, M.A., Madison, A., Ernst, A. and Toom, U. 2024. Dwarf cornulitid tubeworms from the Hirnantian (Late Ordovician) of Estonia. Historical Biology DOI: 10.1080/08912963.2024.2318796

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Meet two new Ordovician fossil species from Estonia — a cover story

The conical fossil above on the cover of the latest issue of Palaeoworld is the paratype of Conchicolites parcecostatis, a new Ordovician (Katian) cornulitid species from the Korgesaare Formation, Sutlema quarry, Estonia. It is tiny, only about two millimeters long. This species, and another new one below, are now formally described and assessed by Vinn et al. (2024). I’m proud to have been on Olev Vinn‘s team for this project, which also included Ursula Toom (Tallinn University of Technology) and Anna Madison (Russian Academy of Sciences).

Above is the paratype of the other new cornulitid species from the same location: Conchicolites sutlemaensis.

The fossils in the Korgesaare Formation of Estonia are diverse and have abundant small cornulitids representing at least a half-dozen species of the genus Conchicolites. This group, the smallest of the cornulitids, appears to have been adapted to soft, muddy seafloors, unlike most other cornulitids that are found attached to hard surfaces such as those of carbonate shells and hardgrounds. These new fossils are thus further documentation of an evolutionary trend towards diverse substrates among the cornulitids in the Great Ordovician Biodiversification Event (GOBE).

Cornulitids, for all their ubiquity in the Lower to Middle Paleozoic, are still phylogenetically mysterious. We don’t yet know their larger evolutionary history, so we can’t definitively place them in any particular phylum yet. They seem most likely related to the microconchids and tentaculitids, which are themselves difficult to place. Cornulitids went extinct in the Carboniferous and apparently left us no living descendants to study.

So, these unassuming little critters have their roles to play in life’s history as they present us with new mysteries to solve. Welcome to the world of named taxa, Conchicolites parcecostatis and Conchicolites sutlemaensis!


Vinn, O., Wilson, M.A., Madison, A. and Toom, U. 2024. Small cornulitids from the Upper Ordovician (Katian) of Estonia. Palaeoworld 33: 57-64 (

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Two new Upper Ordovician bryozoan papers appeared this week

Readers of this blog will remember Kate Runciman, a 2022 graduate of The College of Wooster and now a graduate student at the University of Cambridge. Her Independent Study thesis (after peer review and revisions) has now been published in a conference volume from the 2022 meeting of the International Bryozoology Association (Runciman et al., 2023). She studied growth patterns within large trepostome bryozoan skeletons from the Cincinnati, Ohio, region. They are from various units in the exposed Upper Ordovician (Katian) rocks.

The images above are from acetate peels, with the scale bars equal to 0.50 mm. Figure A shows zooids that grew laterally over a cavity opening, sealing it off with a flat “roof” (C/W-152-2; Amplexopora (?) filiasa). Figure B shows zooids that budded down into a cavity and then angled upwards (C/W-152-1; Amplexopora robusta).

In this new paper, Kate and her colleagues explore the paleoecology of trepostome bryozoans and the various organisms that interacted with them on the Ordovician seafloor. They cover topics from borings, bioclaustrations and parasites to self-overgrowths, brown bodies and “ghosts” of boring inhabitants.

The second paper in the same volume is from a project led by our friend and colleague Caroline Buttler, who is based in the Department of Natural Sciences, Museum Wales, Cardiff. She led a team using non-destructive 3D imaging technology to explore skeletal details of Paleozoic palaeostome bryozoans. The results are spectacular (Buttler et al., 2023). The images obtained by X-ray Micro Computed Tomography (X-ray μCT) and Microscopy (XRM) are have exquisite details.

The images above show the silicified fenestrate bryozoan Oeciophylloporina in 3-D (A) and a “digital thin section” (B). Amazing detail. The specimen is from the Lower Silurian (Aeronian) of the Derenjal Mountains in central Iran.

Another example of the application of this X-ray μCT (the part I was directly involved in) was to look at the internal features of borings in hemispherical calcitic trepostome bryozoans. The above images show a bryozoan from the Upper Ordovician (Sandbian) of Estonia (C/W-231-1). In A the borings are shown in transverse section; in B the segmentation of the borings with the rest of colony are made digitally transparent. We’ve just started to explore what these tomography techniques can tell us about the development of these borings, their possible inhabitants, and how the bryozoans responded to them.

Fossil bryozoology advances!

References Cited

Buttler, C.J., Mitchell, R.L., Wilson, M.A. and Johnston, R.E. 2023. Applications for x-ray tomography/microscopy of Palaeozoic palaeostome bryozoans, p. 1–8. In: Key, M.M., Jr., Porter, J.S. and Wyse Jackson, P.N. (eds) Bryozoan Studies 2022. CRC Press/Balkema, Abingdon and Boca Raton.

Runciman, K.M., Wilson, M.A., Buttler, C.J. and Judge, S.A. 2023. Colony repair strategies in large trepostome bryozoans from the Upper Ordovician (Katian) of the Cincinnati region, USA, p. 105–111. In: Key, M.M., Jr., Porter, J.S. and Wyse Jackson, P.N. (eds) Bryozoan Studies 2022. CRC Press/Balkema, Abingdon and Boca Raton.

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Paleoecology class at Wooster finishes the semester in great style

I was very fortunate this semester to have such a fine class of paleoecologists. This course broadly covers the Earth’s ecological history, so it consists of principles, theories and processes illuminated with case studies, all strung along the thread of geological time. I thus depend on the students to bring in lots of questions and their own research on special topics. This class was brilliant with thee happy tasks. Part of the charm was how many disciplinary majors were represented, from the Earth Sciences through Archaeology and Biology. The above class photo was taken at the end of our last class, which was devoted to student research presentations.

We also had the final lab session in the afternoon. We had many lab projects, but the most challenging has been our analyses of the Upper Ordovician fossils we collected in the first week of classes.

Here is one of the student trays near completion of preparation, identification and labeling.

And our delightful (and very quiet) class mascot was Feather, the companion and service dog for Elise. He is so well trained that there were days I didn’t even know he was present!

A delightful class. I miss them already.

Editor’s addition: Turns out this was my last Paleoecology class. I’m retiring from the College in August 2024. It was a great run of paleo teaching for me — 43 years!


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An Exciting Trip to Tour Unconventional Oil and Gas Wells

This semester’s Geology of Energy Resources course, which focuses on how fossil fuels form, are extracted, and are used, had the opportunity to visit two unconventional oil and gas wells run by Ascent Resources located in southeastern Ohio this week. While most people in the Appalachian Basin think of the Marcellus Shale when it comes to natural gas, this area of Ohio targets the underlying Upper Ordovician Utica Shale.

The trip started with an early morning drive from Wooster down to Salesville Ohio, to visit an unconventional well that was in the final stages of the drilling process. As the vans neared the location the top of a tall metal structure was visible over the trees and an excited murmuring amongst the students began. As the vans pulled up to the gate the group was surprised to see towering walls surrounding the well pad with the top of the drill rig just visible.

After a warm greeting by our hosts each person was outfitted with their own PPE including the ever-stylish blue fire-resistant coveralls, hard hats, and safety glasses (as seen in the first picture and the photo below) and given a safety briefing. What was originally planned as a one-hour tour of this well quickly turned into an almost two-hour tour as there was so much to see and learn, and all the employees even while working were eager to explain and show the students each component of the well drilling process. Students learned that the walls were to block the sound of the drilling process which continues 24/7 until the well is drilled which takes 1-2 weeks from start to finish. Guides walked the group through each stage of the drilling process allowing the students to touch and see the drill pipe, well casings, drill bits, and more. All the while the rig was pulling up drill pipe piece by piece with a rumbling whirr, dropping it into the guiding rails with a loud clang before it was transported to pallets ready to be moved to the next drill site. The group even got to go up onto the derrick of the drill rig and watch the drill pipe being removed from the well up close, which is a very muddy process. By the end of the tour there were no clean shoes (as shown above), but everyone was in great spirits and were eager to see the next well pad.

A short drive later the group arrived at the second well pad which contained four actively producing well heads. This location was in sharp juxtaposition to the loud, crowded, muddy, and constantly moving drilling site. Here there was a solid layer of coarse gravel and distinct areas with machinery and pipes with large spaces in between for vehicles to pass through and little to no mud, though the smell of off gassing from the compressors carried on the air. The no less enthusiastic tour guides at this location walked the group through the plethora of safety measures present at the well pad to ensure worker health, but also protect the environment. Students followed the process from the well heads where the oil and gas exit the well, through the 3-phase separator which isolates oil, gas, and water, to the pipeline which carries the gas to processing facilities, and finally to compressors and storage tanks for the oil. As the temperature began to drop toward the end of the tour and stomachs began grumbling, the tour wrapped up.

Despite the chilly temperature, the group enjoyed a late picnic lunch at Salt Fork State Park, along the shores of Salt Fork Lake. Even as everyone dug into their lunch the discussion was on everything they had seen and heard throughout the day. Finally, everyone hopped back in the vans to warm up and drive back to campus. The discussions continued during the first part of the drive until students began to doze off from the combination of an early morning, exciting but busy day, and the cold weather with a warm car.

Students will be writing a report about the trip and will also be using the information they gained in a class debate regarding the potential pros and cons of oil and gas wells.

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A delightful little field trip in Ohio with a Polish-American team

Today was astonishingly beautiful in Ohio: bright blue skies and the peak of fall leaf colors. By happy circumstance, I had three Polish paleontologist friends visiting Wooster after the Geological Society of America Annual Meeting in Pittsburgh last week. Greg Wiles very generously drove us down to Caesar Creek State Park for a few hours of fossil collecting from Ordovician exposures in the emergency spillway of the lake. From the left the team consisted of Greg Wiles, me, Jakub Słowiński, and Michał Zatoń, the latter two from the Department of Palaeontology & Stratigraphy, University of Silesia. Tomek Zatoń took the photograph.

We’ve recorded this locality many times in this blog. I just want to record this trip and show the best fossil find of the day. Above is part of the cephalon of the large trilobite Isotelus maximus. Michał found it in the float on the spillway floor.

Again, wonderful day. Thank you Greg Wiles for your participation and driving. And thanks to my Polish friends for making this field trip possible on a sunny Monday.

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Freshwater sponge and diatom team presents at the annual Geological Society of America meeting in Pittsburgh

This summer Garrett Robertson and Minnie Pozefsky performed superb research on the sponges and diatoms in a core from Brown’s Lake near Shreve, Ohio. Their project is summarized here. Today Garrett presented their work, along with others on the NSF-funded team, at the Annual Meeting of the Geological Society of America in Pittsburgh, Pennsylvania. Garrett is pictured above with the poster. (Thanks, Greg Wiles, for the image!)

Minnie Pozeksky, shown above, specialized in the diatoms, mastering their taxonomy, paleoecology, and statistical distribution. She is now a first-year student at Williams College. Garrett is finishing his Senior Independent Study at Wooster on the sponges this year.

In this photomicrograph, one of Garrett’s sponge spicules is above, and one of Minnie’s diatoms is below.

Garrett and Minnie were a fun, creative and very productive team to work with. Their work will continue as we add to it over the next summer.

Wooster was very well represented at this GSA meeting by faculty, students and alumni. We have a proud tradition of mentored research at Wooster. At meetings like this, where our current students converse with our alumni, we see the compounding value of this research over the years.


Robertson, G.R.*, Pozefsky, M.E.*, Wilson, M.A., Wiles, G.C., Wiesenberg, N., Lowell, T.V., Diefendorf, A.F. and Corcoran, M. 2023. Preliminary analysis and paleoenvironmental assessment of the sponges and diatoms preserved in a Late Holocene to Recent sediment core from Brown’s Lake, Wayne County, Ohio. Geological Society of America Abstracts with Programs, vol. 55, no. 6, doi: 10.1130/abs/2023AM-392825.


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