Team Cincinnati moves into Kentucky for additional fieldwork

March 12th, 2017

Maysville, Kentucky — It was another frigid morning under the clear, pitiless skies of the Cincinnati region, but Luke Kosowatz (’17) was in good spirits. He is collecting at our first stop of the day: an exposure of the Bellevue Formation (Upper Ordovician, Katian) along the Bullitsville Road in northern Kentucky (N 39.08121°, W 84.79230°; C/W-152). Luke is sorting out bioeroded bryozoans and brachiopods here.

Matt Shearer (’18) joins Luke on the outcrop. If the place looks familiar it’s because William Harrison (’15) and I were here almost exactly three years ago.

In cosmic irony, the Bullitsville outcrop is nearly a neighbor of the Creation Museum. It was closed this Sunday morning — who would have guessed? Do Creationists ponder the fact that their pseudoscientific establishment sits on an incredible record of fossils 450 million years old? They do indeed: “These conditions and processes would be expected during the global catastrophic Flood described in the Scriptures. The thin alternating coarse-grained limestone and fine-grained shale layers could be deposited quickly under such catastrophic conditions.” Of course.

We were also near Big Bone Lick State Park, the birthplace of American vertebrate paleontology.

This site has an excellent life-sized diorama of Late Pleistocene animals (mammoths, mastodons, bison, ground sloths and even vultures) getting mired in bogs infused with salty water.

Team Cincinnati then traveled east for about an hour to the magnificent exposures of the Cincinnatian Group around Maysville, Kentucky. Here we targeted the Corryville Formation exposed along the AA Highway (N 38.60750°, W 83.76775°).

As with all our sites, the fossils are extraordinary. This is an ordinary slab of limestone from the Corryville with dozens of well-preserved strophomenid brachiopods.

For nostalgia on my part, we visited an outcrop along US 62 at the southern edge of Maysville where the Corryville Formation is again exposed (N 38.60932°, W 83.81070°). It is at this site that I collected a cave-dwelling bryozoan fauna now the subject of a manuscript Caroline Buttler (National Museum Wales) and I are finishing up this month. The cave interval was destroyed by later roadwork, but the remaining outcrops were superb for our purposes.

We ended the field day about seven kilometers north at another outcrop of the Corryville along US 62 (N 38.6445°, W 83.77678°).  I was so distracted by the diversity of fossils that I forgot to take pictures!

Dinner was at El Caminante Mexican Restaurant in Maysville. It was so good we are compelled to recommend it to future geological visitors.

Wooster Geologists launch Team Cincinnati 2017

March 11th, 2017

Harrison, Ohio — Our first fieldwork of the year started on this cold, cold March day in southeastern Indiana. (Note the white icicles on the outcrop.) Luke Kosowatz, Matt Shearer and I have begun our projects in the magnificent Cincinnatian Group (Upper Ordovician, Katian) with its fantastic fossils on the first day of Wooster’s spring break. Despite the sunlight, it was 19°F when we had to leave the warm vehicle to start collecting fossils at our first stop shown above. This is the US 27 roadcut outside Richmond, Indiana, beloved by paleontologists (N 39.78631°, W 84.90318°). Here the lower Whitewater Formation is well exposed and weathered just right to release millions of fossils from their rocky tombs. Luke is studying patterns of bioerosion (almost entirely borings) in the Cincinnatian for his Independent Study thesis, and Matt is examining the distribution of bryozoan taxa for his I.S. work. We’ll have more details on their investigations later.

Today we started at the top of the Cincinnatian Group and worked our way down section as we moved south through Indiana towards the Ohio River. One of our sites was the Brookville Lake Dam emergency spillway exposure, seen above on the other end of the dam.

We climbed up the dam itself to get to the spillway exposure, which is magnificent. We did not collect here, though, because we couldn’t assure tight stratigraphic control of our specimens. There is too much downslope movement of fossils and rocks at this site for us to be certain about the horizons from which the fossils came.

Southgate Hill is a spectacular series of roadcuts north of St. Leon, Indiana (N 39.33909°, W 84.95306°). Matt and Luke are here collecting from the top of the Waynesville Formation.

Our last outcrop of the day was at the top of this sequence of limestones and shales exposed at another large roadcut, this one near Lawrenceburg, Indiana (N 39.09863°, W 84.87683°). At the very top is the rubbly Bellevue Formation, from which we collected magnificent trepostome bryozoans, many with beautiful borings.

Despite the temperatures, we had fun today and look forward to another three days of field paleontology in what must be the most fossiliferous rocks in the world. We are fortunate to live so close to these treasures.

Wooster’s Fossil of the Week: Encrusting craniid brachiopods (Upper Ordovician of southeastern Indiana)

March 10th, 2017

The two irregular patches above are brachiopods known as Petrocrania scabiosa encrusting the ventral valve of yet another brachiopod (Rafinesquina). That species name “scabiosa” is evocative if not a little unpleasant — it is also the root of the English “scab”.

Petrocrania scabiosa is in a group of brachiopods we used to call “inarticulates” because their two valves are not articulated by a hinge as they are in most brachiopods. Instead they are held together by a complex set of muscles. Now we place these brachiopods in the Class Craniforma, an ancient group which originated in the Cambrian and is still alive today.

Petrocrania scabiosa was a filter-feeder like all other brachiopods, extracting nutrients from the seawater with a fleshy lophophore. The Wooster specimens are part of our large set of encrusting fossils (a type of sclerobiont) in our hard substrate collection. They have irregular shells that are circular in outline when they grew alone, and angular when they grew against each other.

Some craniid brachiopods were so thin that their shells repeated the features of the substrate underneath them, a phenomenon known as xenomorphism (“foreign-form”).

Petrocrania scabiosa brachiopods (circular) on a Rafinesquina brachiopod, along with a trepostome bryozoan that encrusted some brachiopods and grew around others. The P. scabiosa on the far left shows xenomorphic features. Specimen borrowed from the University of Cincinnati paleontology collections.

A 2007 College of Wooster paleontology field trip to the Upper Ordovician locality near Richmond, Indiana, where these specimens were found. Students are in the traditional paleontological poses.

[Originally published May 22, 2011.]

Wooster’s Fossil of the Week: Mysterious tentaculitids (Devonian of Maryland)

March 3rd, 2017

The sharp little conical fossils above are common Paleozoic fossils, especially in the Devonian. They are tentaculitids now most commonly placed in the Class Tentaculitoidea Ljashenko 1957. Tentaculitids appeared in the Ordovician and disappeared sometime around the end of the Carboniferous and beginning of the Permian. These specimens are from the Devonian of Maryland.

The systematic placement of the tentaculitids has been controversial. Their straight, narrow shells are usually ornamented by concentric rings, and many had septa (thin shelly partitions) inside the cones. The microstructure of the shells is most interesting — it looks very much like that of brachiopods and bryozoans. For this reason and several others, several of my colleagues and I believe the tentaculitids were lophophorates (animals that filter-feed with a tentacular device called a lophophore). They may thus be related to other problematic tubeworms like microconchids and cornulitids (Taylor et al., 2010).

Tentaculitids from the New Creek Limestone (Lochkovian, Early Devonian) of New Creek, West Virginia.

Knowing how the tentaculitids fit into an evolutionary scheme, though, has not helped us figure out what they did for a living. The figure below, from Cornell et al. (2003), shows these funny cones in just about every lifestyle imaginable!

References:

Cornell, S.R., Brett, C.E. and Sumrall, C.D. 2003. Paleoecology and taphonomy of an edrioasteroid-dominated hardground association from tentaculitid limestones in the Early Devonian of New York: A Paleozoic rocky peritidal community. Palaios 18: 212-224.

Taylor, P.D., Vinn, O. and Wilson, M.A. 2010. Evolution of biomineralization in ‘lophophorates’. Special Papers in Palaeontology 84: 317-333.

[Originally published May 29, 2011.]

Dr. Rob Thieler delivers the 36th annual Richard G. Osgood, Jr., Memorial Lecture at Wooster

March 2nd, 2017

One of the pleasures of being in the Geology Department at The College of Wooster is that we have the annual Richard G. Osgood, Jr., Memorial Lecture series. These presentations, given in honor of the late Professor Osgood, have significantly enriched our intellectual lives. Funds from the endowment are used to bring to Wooster internationally-recognized Earth scientists. Last night the 36th Osgood Lecture had an overflow crowd in Lean Lecture Room. It was an excellent event in every way.

Our speaker was Dr. Rob Thieler, Director of the U.S. Geological Survey Coastal and Marine Science Center. His title was “Changing Climate, Changing Coasts”.

Dr. Thieler outlined the causes and consequences of sea-level rise on coastal systems. It is a complex topic, but he made it accessible to everyone. The projected changes are grim enough, but he emphasized to students the critical need now and in the  future for people who can communicate science effectively to the public, and for decision-makers to have strong foundational awareness of geological context. Sounds like the ideal mission for a liberal arts geology program.

Dr. Rob Thieler on, appropriately, a coastline. We thank him for his clear, provocative and information-rich talk, and his wonderful interactions with our students. Thank you again to the Osgood family for endowing this spectacular lecture series.

Professors Greg Wiles and Meagen Pollock earn a field experience grant from the Keck Geology Consortium

February 26th, 2017

Wooster, Ohio — Two Wooster Geology Professors, Meagen Pollock and Greg Wiles, have a exciting new grant from the Keck Geology Consortium to fund a five-week research program for first-year and sophomore students interested in the Earth Sciences. The experience will involve summer field trips in Alaska and Utah. Great news! Congratulations to Greg and Meagen. New opportunities for future Wooster Geologists. See the full press release here.

Wooster’s Fossil of the Week: A scaphitid ammonite (Late Cretaceous of Mississippi)

February 24th, 2017

The beauty above is Discoscaphites iris (Conrad, 1858) from the Owl Creek Formation of Ripley, Mississippi. Megan Innis and I collected it during our expedition to the Cretaceous-Paleogene boundary in the southern United States last summer. It is a significant index fossil in biostratigraphy: the Discoscaphites iris Zone is the latest in the Cretaceous (the late Maastrichtian Stage). This animal lived in the final days of the Mesozoic Era just before the mass extinction 65.5 million years ago.

Discoscaphites iris is an ammonite, a type of extinct cephalopod mollusk related to the modern octopus, squid and nautilus. It had a planispirally-coiled shell with chambers divided from each other by complexly-folded walls. If you look closely near the top of the fossil above, you will see where the shell has flaked away revealing an internal mold of sediment and a peek at the folded walls inside. “Ammonite”, by the way, is a very old term for these fossils. Pliny the Elder himself used a variant of the name, which comes from the Egyptian god Amun with his occasional coiled ram’s horn headgear.

Reconstruction of an ammonite by Arthur Weasley (via Wikipedia).

Ammonite shells were made of the carbonate mineral aragonite. This is the mineral that makes many modern mollusk shells have prismatic colors, which we call nacreous. You may know it best as “mother of pearl” or as pearls themselves. Aragonite has an unstable crystal structure and so is not common in rocks older than a few million years. The original aragonite in our ammonite fossil is thus a bonus.

In an oddly topical note, Discoscaphites iris was recently found in the Upper Cretaceous of Libya, giving it a disjunct range from the US Gulf and Atlantic coasts to the Mediterranean coast of northern Africa (Machalski et al., 2009).

Reference:

Machalski, M., Jagt, J.W.M., Landman, N.H. and Uberna, J., 2009. First record of the North American scaphitid ammonite Discoscaphites iris from the upper Maastrichtian of Libya. N. Jb. Geol. Paläont. Abh. 254: 373-378.

[Originally published April 24, 2011]

Wooster’s Fossil of the Week: A stromatoporoid (Middle Devonian of central Ohio)

February 17th, 2017

Stromatoporoids are very common fossils in the Silurian and Devonian of Ohio and Indiana, especially in carbonate rocks like the Columbus Limestone (from which the above specimen was collected). Wooster geologists encountered them frequently on our Estonia expeditions in the last few years, and we worked with at least their functional equivalents in the Jurassic of Israel (Wilson et al., 2008).

For their abundance, though, stromatoporoids still are a bit mysterious. We know for sure that they were marine animals of some kind, and they formed reefs in clear, warm seas rich in calcium carbonate (DaSilva et al., 2011). Because of this tropical habit, early workers believed they were some kind of coral, but now most paleontologists believe they were sponges. Stromatoporoids appear in the Ordovician and are abundant into the Early Carboniferous. The group seems to disappear until the Mesozoic, when they again become common with the same form and life habits lasting until extinction in the Late Cretaceous (Stearn et al., 1999).

The typical stromatoporoid has a thick skeleton of calcite with horizontal laminae, vertical pillars, mounds on the upper surface called mamelons, and dendritic canals called astrorhizae shallowly inscribed on the mamelons. These astrorhizae are the key to deciphering what the stromatoproids. They are very similar to those on modern hard sponges called sclerosponges. Stromatoporoids appear to be a kind of sclerosponge with a few significant differences (like a calcitic instead of an aragonitic skeleton).

Stromatoporoid anatomy from Boardman et al. (1987).

Top surface of a stromatoporoid from the Columbus Limestone showing the mamelons.

There is considerable debate about whether the Paleozoic stromatoporoids are really ancestral to the Mesozoic versions. There may instead be some kind of evolutionary convergence between two groups of hard sponges. The arguments are usually at the microscopic level!

The stromatoporoids were originally named by Nicholson and Murie in 1878. This gives us a chance to introduce another 19th Century paleontologist whose name we often see on common fossil taxa: Henry Alleyne Nicholson (1844-1899). Nicholson was a biologist and geologist born in England and educated in Germany and Scotland. He was an accomplished writer, authoring several popular textbooks, and a spectacular artist of the natural world. Nicholson taught in many universities in Canada and Great Britain, finally ending his career as Regius Professor of Natural History at the University of Aberdeen.

Henry Alleyne Nicholson (1844-1899) from the University of Aberdeen museum website.

References:

Boardman, R.S., Cheetham, A.H. and Rowell, A.J. 1987. Fossil Invertebrates. Wiley Publishers. 728 pages.

DaSilva, A., Kershaw, S. and Boulvain, F. 2011. Stromatoporoid palaeoecology in the Frasnian (Upper Devonian) Belgian platform, and its applications in interpretation of carbonate platform environments. Palaeontology 54: 883–905.

Nicholson, H.A. and Murie, J. 1878. On the minute structure of Stromatopora and its allies. Linnean Society, Journal of Zoology 14: 187-246.

Stearn, C.W., Webby, B.D., Nestor, H. and Stock, C.W. 1999. Revised classification and terminology of Palaeozoic stromatoporoids. Acta Palaeontologica Polonica 44: 1-70.

Wilson, M.A., Feldman, H.R., Bowen, J.C. and Avni, Y. 2008. A new equatorial, very shallow marine sclerozoan fauna from the Middle Jurassic (late Callovian) of southern Israel. Palaeogeography, Palaeoclimatology, Palaeoecology 263: 24-29.

[Originally published on October 30, 2011]

Coring the Bog – An 18,000 Year Record of Environmental Change

February 13th, 2017

Two class projects kick off the Climate Change 2017 course. The first deals with tree-ring dating (dendrochronology, blog post coming soon) of historical structures and then analyzing the tree-rings for their climate significance. The second is is shown below and it concerned with analyzing sediment cores from Browns Lake Bog that document climate variability since the last Ice Age. Below are some photos of the bog coring – great thanks to Dr. Tom Lowell and his Glacial Geology class from the University of Cincinnati – the folks who did most of the work.

Setting up the coring rig at Browns Lake – early in the day snow covered the ground by 4 pm it was gone (albedo feedback in play).

The core boss (Dr. Tom Lowell) oversees the extraction of another meter of mud from the bog.

The probing team sends down 7 rods through the mud until refusal. Mapping the mud thickness gives an idea of the geometry of the bog and allows for the construction of an isopach map.

Extracting peat – the upper 5 meters or so are peat (significant amount of sphagnum moss and carbon). Note the trees, it is not a sphagnum bog now here.

Setting up the production line and assigning teams and tasks.

Coring a tree to determine the recruitment time – the hypothesis is that these trees moved into the bog recently (past 200 years) – the first trees here since the Ice Age. This nutrient limited bog was fertilized by wind blown dust during European Settlement allowing these vascular plants to obtain a foothold in the previously sphagnum moss dominated bog.

Hey there is a Wooster student – good job Ben. This white oak is growing on the top of  a kame and it has witnessed the changes in the climate and land use for the last 300 years.


Nick samples the bog water for its isotopic composition. This is work done in collaboration with isotope geologists at the University of Cincinnati.

Wooster’s Fossil of the Week: A receptaculitid (Middle Ordovician of Missouri)

February 10th, 2017

This week’s fossil is a long-standing paleontological mystery. Above is a receptaculitid from the Kimmswick Limestone (Middle Ordovician) near Ozora, Missouri. I think I found it on a field trip with Frank Koucky in the distant mists of my student days at Wooster, but so many outcrops, so many fossils …

Below is a nineteenth century illustration of a typical receptaculitid fossil. They are sometimes called “sunflower corals” because they look a bit like the swirl of seeds in the center of a sunflower. They were certainly not corals, though, or probably any other kind of animal. Receptaculitids appeared in the Ordovician and went extinct in the Permian, so they were confined to the Paleozoic Era. Receptaculitids were bag-like in form with the outside made of mineralized pillars (meroms) with square or diamond-shaped heads. The fossils are usually flattened disks because they were compressed by burial. You may notice now that the fossil at the top of this post is a mold of the original with the dissolved pillars represented by open holes. (Paleontologists can argue if this is an external or internal mold.)So what were the receptaculitids? When I was a student we called them a kind of sponge, something like a successor of the Cambrian archaeocyathids. In the 1980s a convincing case was made that they were instead a kind of alga of the Dasycladales. Now the most popular answer is that they belong to that fascinating group “Problematica”, meaning we have no idea what they were! (Nitecki et al., 1999). It’s those odd meroms that are the problem — they appear in no other known group, fossil or recent.

I find it deeply comforting that we still have plenty of fossils in the Problematica. We will always have mysteries to puzzle over.
Another Wooster receptaculitid specimen, this time seen from the underside showing side-views of the meroms.
Diagram of a receptaculitid in roughly life position showing its inflated nature and pillar-like meroms. From Dawson (1880, fig. 25): a, Aperture (probably imaginary here). b, Inner wall. c, Outer wall. n, Nucleus, or primary chamber. v, Internal cavity.

Finally, this is what a typical receptaculitid looks like in the field (Ordovician of Estonia). Note that nice sunflower spiral of the merom ends.

References:

Dawson, J.W. 1880. The chain of life in geological time: A sketch of the origin and succession of animals and plants. The Religious Tract Society, 272 pages.

Nitecki, M.H., Mutvei, H. and Nitecki, D.V. 1999. Receptaculitids: A Phylogenetic Debate on a Problematic Fossil Taxon. Kluwer Academic/Plenum, 241 pages.

[Originally published on September 18, 2011]

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