Archive for the 'Uncategorized' Category

Expanding Horizons by Mapping the Seafloor

April 24th, 2017

Wooster, OH – Last weekend, The College of Wooster hosted the Expanding Your Horizons conference. About 240 fifth- and sixth-grade girls participated in hands-on science workshops on computer science, math, geology, chemistry, biology, physics, and neuroscience. This year, I went back to my roots in marine geology to run a workshop on how we see what’s on the seafloor.

Pre-workshop selfie, complete with “I love rocks” name tag and photo of the Alvin submersible to jumpstart our conversations.

I put together a version of this activity about how geologists “see” under ice, the ocean, or inside the Earth. Most of the girls guessed that we use sonar to measure the depth of the ocean floor, and this short video was helpful for understanding how sonar works. Each group of girls was given a shoebox containing a mystery letter. They used their “sonar straws” to probe the bottom of the shoebox. They plotted their measured depths on their grid and used their data to interpret the letter in the box.

Poking straws into boxes seems not-at-all scientific and maybe a little silly at first, but the girls starting making and testing hypotheses pretty quickly.

You can see the map of “hits” and “misses” as they record the results of their hypothesis testing.

We found that the easiest letters to identify were those that had right angles, like “I” and “E.” Letters with triangles (like “N”) or curves (like “S” and “C”) were harder to identify.

Along the way, we learned about reproducibility and sampling strategy. As it turns out, if your data point is wrong, or all of your data are clustered in one corner of the map, it’s hard to make an interpretation. Still, each session managed to collect enough data to interpret the word “S-C-I-E-N-C-E” when the groups brought their maps together.

We watched part of a video on women in oceanography and I told them about Deep Sea Dawn, an inspirational woman oceanographer who maps the ocean floor and builds Legos! The girls asked incredible questions about what it’s like to be out at sea and about my favorite rock (basalt, of course). Finally, we watched a video about how we shrink styrofoam cups when we conduct deep-sea research and I showed them some of the cups from my cruises.

Their enthusiasm and energy were the best reminders of why I do what I do. I’m so grateful to all of my colleagues and educators everywhere who work hard every day to inspire the next generation of young geoscientists.

Wooster Geologists participate in the historic March For Science on Earth Day, 2017

April 22nd, 2017

Wooster, Ohio — It was a chilly day downtown, but several hundred people gathered for the national March For Science. We were one of over 500 local events across the country advocating for science awareness, education and funding. Thank you very much for retired Wooster Professor of Biology Lyn Loveless for organizing such a complex meeting with speakers and break-out discussions in local businesses. It was a great success. Above are some of the signs held by children in attendance. Several Wooster Geologists were in the diverse crowd, and some participated directly.

One view of the attendees. We all see the distinctive profile of Dr. Wiles in the foreground. Kelli Baxstrom may recognize someone on the far right!

One of the speakers was ace Wooster physicist and former dean Dr. Shila Garg. Note her coat on this mid-April day.

I include this photo (taken by Wooster political scientist Matt Krain) of Dr. Wiles and me to show my Paleontological Society colleagues that I wore The Shirt, even if no one noticed under the jacket.

One of the break-out sessions was on climate change. Greg Wiles and Clara Deck (’17) did great outreach work explaining their research to the large gathering. Wooster’s paleoclimate and climate change research and education is making a difference. Visit the Tree-Ring Lab website to see more details about the operation.

It was an inspiring afternoon, especially seeing the many young scientists and scientists-to-be who participated. Of course, for someone my age it is astonishing that we have to advocate for something so self-evidently beneficial as science, but such are our times.

Wooster’s Fossil of the Week: A Biserial Graptolite (Middle Ordovician of Tennessee)

April 21st, 2017

This week’s fossils are graptolites (from the Greek for written rocks) I found many years ago in the Lebanon Limestone near the town of Caney Springs south of Nashville, Tennessee. They are of the genus Amplexograptus and probably belong to the species A. perexcavatus (Lapworth, 1876).

Graptolites were colonial organisms consisting of hundreds and sometimes thousands of tiny zooids (individuals) connected together in a flexible proteinaceous skeleton (the rhabdosome). They first appeared in the Late Cambrian (around 510 million years ago) and disappeared forever in the Early Carboniferous (around 350 million years ago). Amplexograptus colonies were probably attached to floats so they could drift through the ancient oceans filtering out organic particles; they would be officially “passively mobile planktonic suspension feeders”. They belong to the Phylum Hemichordata, although there have always been disputes about their actual evolutionary relationships. This matters because graptolites are important index fossils for sorting out the age relationships of Lower and Middle Paleozoic rocks.

Graptolites are usually preserved as thin carbonaceous films on dark shales, making them rather hard to see (as my paleontology students will readily agree). The great 18th Century naturalist Linnaeus even said that they were “pictures resembling fossils rather than true fossils”. Sometimes, though, they are found in lighter-colored rocks like limestones, as above. Goldman et al. (2002) found Amplexograptus in limestones preserved in three dimensions, possibly because the limestones were cemented early around them before they collapsed with decay. They even studied this same species from the Lebanon Limestone. The 3-D preservation allows for a much more detailed analysis of the tiny cups (thecae) which held the individual zooids. It is possible that I could dissolve the limestone shown above and retrieve some delicate three-dimensional graptolites — but I could also just as easily destroy them.

Amplexograptus perexcavatus was originally described in 1876 by the famous geologist Charles Lapworth (1842-1920), who referred it to the genus Diplograptus. Actually, he had two species in his D. perexcavatus group, so it took some taxonomic detective and legal work to fix the current naming system. Lapworth, who I’ve figured below with an inset of his not-very-helpful diagram of the original D. perexcavatus, is well known by paleontologists for his work with graptolites as index fossils. Scientists and historians of science know him as the man who invented the Ordovician Period in 1879 to solve a bitter dispute between Roderick Murchison and Adam Sedgwick who each claimed the same rock interval in Wales for the Silurian and Cambrian periods respectively. Lapworth’s primary biostratigraphic argument for the Ordovician as a separate period was the distribution of graptolites, including our friend Amplexograptus perexcavatus. (Murchison and Sedgwick were long gone by the time their dispute was settled.)

(Charles Lapworth. Image courtesy of The Lapworth Museum of Geology.)

References:

Goldman, D., Campbell, S.M. and Rahl, J.M. 2002. Three-dimensionally preserved specimens of Amplexograptus (Ordovician, Graptolithina) from the North American mid-continent: taxonomic and biostratigraphic significance. Journal of Paleontology 76: 921-927.

Lapworth, C. 1876. The Silurian System in the South of Scotland, p. 1–28. In: Armstrong, J. Young, J. and Robertson, D. (eds.), Catalogue of Western Scottish Fossils. Blackie and Son, Glasgow.

[Originally posted August 28, 2011]

Wooster’s Fossil of the Week: A Conulariid (Lower Carboniferous of Indiana)

April 14th, 2017

I have some affection for these odd fossils, the conulariids. When I was a student in the Invertebrate Paleontology course taught Dr. Richard Osgood, Jr., I did my research paper on them. I had recently found a specimen in the nearby Lodi City Park. It was so different from anything I had seen that I wanted to know much more. I championed the then controversial idea that they were extinct scyphozoans (a type of cnidarian including most of what we call today the jellyfish). That is now the most popular placement for these creatures today, although I arrived at the same place mostly by luck and naïveté. (I love the critical marks in that word! And yes, I always have to look them up.)

The specimen above is Paraconularia newberryi (Winchell) found somewhere in Indiana and added to the Wooster fossil collections before 1974. (The scale below it is in millimeters.) A close view (below) shows the characteristic ridges with a central seam on one of the sides.
Conulariids range from the Ediacaran (about 550 million years ago) to the Late Triassic (about 200 million years ago). They survived three major extinctions (end-Ordovician, Late Devonian, end-Permian), which is remarkable considering the company they kept in their shallow marine environments suffered greatly. Why they went extinct in the Triassic is a mystery.

The primary oddity about conulariids is their four-fold symmetry. They had four flat sides that came together something like an inverted and extended pyramid. The wide end was opened like an aperture, although sometimes closed by four flaps. Preservation of some soft tissues shows that tentacles extended from this opening. Their exoskeleton was made of a leathery periderm with phosphatic strengthening rods rather than the typical calcite or aragonite. (Some even preserve a kind of pearl in their interiors.) Conulariids may have spent at least part of their life cycle attached to a substrate as shown below, and maybe also later as free-swimming jellyfish-like forms.

It is the four-fold symmetry and preservation of tentacles that most paleontologists see as supporting the case for a scyphozoan placement of the conulariids. Debates continue, though, with some seeing them as belonging to a separate phylum unrelated to any cnidarians. This is what’s fun about extinct and unusual animals — so much room for speculative conversations!

[Thanks to Consuelo Sendino of The Natural History Museum (London) for correcting the age range of these fascinating organisms.]

References:

Hughes, N.C., Gunderson, G.D. and Weedon, M.J. 2000. Late Cambrian conulariids from Wisconsin and Minnesota. Journal of Paleontology 74: 828-838.

Van Iten, H. 1991. Evolutionary affinities of conulariids, p. 145-155; in Simonetta, A.M. and Conway Morris, S. (eds.). The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press, Cambridge.

[Modified from an original post on July 31, 2011]

Wooster’s Fossils of the Week: Bivalve escape trace fossils (Devonian and Cretaceous)

April 7th, 2017

It is time again to dip into the wonderful world of trace fossils. These are tracks, trails, burrows and other evidence of organism behavior. The specimen above is an example. It is Lockeia James, 1879, from the Dakota Formation (Upper Cretaceous). These are traces attributed to infaunal (living within the sediment) bivalves trying to escape deeper burial by storm-deposited sediment. If you look closely, you can see thin horizontal lines made by the clams as they pushed upwards. These structures belong to a behavioral category called Fugichnia (from the Latin fug for “flee”). They are excellent evidence for … you guessed it … ancient storms.
The specimens above are also Lockeia, but from much older rocks (the Chagrin Shale, Upper Devonian of northeastern Ohio). Both slabs show the fossil traces preserved in reverse as sediment that filled the holes rather than the holes themselves. These are the bottoms of the sedimentary beds. We call this preservation, in our most excellent paleontological terminology, convex hyporelief. (Convex for sticking out; hyporelief for being on the underside of the bed.)

The traces we know as Lockeia are sometimes incorrectly referred to as Pelecypodichnus, but Lockeia has ichnotaxonomic priority (it was the earliest name). Maples and West (1989) sort that out for us.
Uriah Pierson James (1811-1889) named Lockeia. He was one of the great amateur Cincinnatian fossil collectors and chroniclers. In 1845, he guided the premier geologist of the time, Charles Lyell, through the Cincinnati hills examining the spectacular Ordovician fossils there. He was the father of Joseph Francis James (1857-1897), one of the early systematic ichnologists.

References:

James, U.P. 1879. The Paleontologist, No. 3. Privately published, Cincinnati, Ohio. p. 17-24.

Maples, C.G. and Ronald R. West, R.R. 1989. Lockeia, not Pelecypodichnus. Journal of Paleontology 63: 694-696.

Radley, J.D., Barker, M.J. and Munt, M.C. 1998. Bivalve trace fossils (Lockeia) from the Barnes High Sandstone (Wealden Group, Lower Cretaceous) of the Wessex Sub-basin, southern England. Cretaceous Research 19: 505-509.

[Originally published January 29, 2012]

Wooster’s Fossils of the Week: A slab of Upper Ordovician bivalves from northern Kentucky

March 31st, 2017

Earlier this month, Luke Kosowatz, Matt Shearer and I went on a field trip through the Cincinnati region collecting Upper Ordovician (Katian) bryozoans and examples of bioerosion for their Independent Study projects and other investigations. I picked up the above slab and put it in our vehicle for future study not because of its beauty, but the preservational modes it displays. The black, rounded objects are bivalves, probably of the Order Modiomorphida. They are miserable fossils to identify because they originally had shells made of the mineral aragonite, which dissolved quickly after the animals died. What is left are a few scrappy molds and that black film. This is a common preservation of bivalves in the Cincinnatian.

This is the Corryville Formation outcrop from which the slab came. It is just west of Maysville, Kentucky, along the AA Highway (N 38.60750°, W 83.76775°; C/W-740).

Here is the slab along the roadside before we cleaned it up. Not much to see, really, except the low-relief black blobs that are remains of bivalves.

As you see, not much detail in the bivalves other than an outline matching somewhat the modiomorphids. Those of you with sharp paleontological eyes will note a round gray patch with radiating lines. This is a bryozoan that was attached to the bivalve shell. When the shell dissolved, the bryozoan attachment surface became visible. In other words, this is an upside-down encrusting bryozoan, a condition we’ve seen several times in this blog.

Here’s another bivalve with an upside-down encrusting bryozoan. This time you can see that the black film was underneath the bryozoan and on the outside of the bivalve shell. In a 2004 paper, Tim Palmer and I wrote: “We have also long been curious about why some of the epifaunal aragonitic Ordovician genera in the Cincinnatian such as Modiolopsis are preserved with a thick black outer shell covering (e.g. Pojeta 1971, pl. 15, fig. 6). It now seems likely that this was a hypertrophied periostracum that conferred some protection against dissolution during life, similar to the situation seen in Recent unionids that are susceptible to dissolution in their fresh-water habitats” (p. 425). Maybe it’s time we followed up on these speculations? I’m sure other paleontologists have had similar ideas.

Among the indistinct modiomorphid bivalves is this old friend: Ambonychia with its characteristic radiating ridges.

References:

Palmer, T.J. and Wilson, M.A. 2004. Calcite precipitation and dissolution of biogenic aragonite in shallow Ordovician calcite seas. Lethaia 37: 417-427.
Pojeta, J. 1971. Review of Ordovician pelecypods. United States Geological Survey, Professional Paper 695, 1-46.

Dating the Tracy House (Apple Creek, Ohio)

March 25th, 2017

Climate Change 2017 is pleased to have been asked to date the Tracy House, Apple Creek Ohio. The log house/cabin is now stored in the soon to be Apple Creek Community Center and Library will be reassembled this coming summer. The date is unambiguous and most of the timber was cut after the growing season of 1826 and it is likely that the house was originally constructed in 1827, one of the first to be built in the East Union Township. A copy of our report can be found here.
The class cores an old growth living tree to help assemble a calendar dated tree ring chronology.

Dean extracts a core from a beam of the Tracy House under the watchful eye of Annette – the TA, as Conner looks on.

Extracting a core being careful to preserve the outer ring of the core (don’t bend the extractor John).

Another successful core extracted.


Graph showing an 100 year overlap between the North East Ohio (NEO) living ring-width chronology and the ring-width chronology from the Tracy House. For the full 230 year period of overlap the correlation is 0.75 – pretty impressive, it shows the power of tree-ring dating and the sensitivity of white oak to climate in Ohio. To learn more about the utility of this data view this.

 

Special thanks to the Apple Creek Historical Society for working with us on this project.

The group resting after work on a 70 degree F day in February at Browns Lake Bog where they cored some of the remnant old growth oak stands of Northeast Ohio (above). The group getting the run down at Apple Creek (below).

 

Wooster’s Fossils of the Week: Strophomenid brachiopods from the Upper Ordovician of southern Ohio

March 24th, 2017

Usually I find fossils in the field or lab and then craft a Fossil of the Week entry around them. This time, though, I started with a paper and then searched for fossils to illustrate it. I found this recent paper very well done:

Bauer, J.E. and Stigall, A.L. 2016. A combined morphometric and phylogenetic revision of the Late Ordovician brachiopod genera Eochonetes and Thaerodonta. Journal of Paleontology 90: 888-909.

It does classic systematics on a group of brachiopods with the modern tools of morphometric and phylogenetic analyses. Its conclusions are direct and convincing: The genus Thaerodonta is synonymous with Eochonetes, and a variety of species are shifted around, solving problems that have lingered for over a century, Plus as a bonus, who can’t love a new species named Eochonetes voldemortus? So I set out to find specimens of this brachiopod group in our collections. Above are internal valve views of the brachiopod Eochonetes clarksvillensis (Foerste, 1912), showing characteristic denticles (little teeth) along the hinge line. Below are external valve views. Jen Bauer herself kindly confirmed the identifications!

These specimens come from the Waynesville Formation (Katian) exposed at Caesar Creek in southern Ohio, a place we have had many paleontology field trips. E. clarksvillensis is common in the Waynesville and overlying Liberty formations. Read much more about it in Bauer and Stigall (2016).

The genus Eochonetes was named by Frederick Richard Cowper Reed in 1917 from the Ordovician of Scotland. (The British Isles were not too far away from Ohio in the Late Ordovician.) Reed was born in London in 1869 and died in Cambridge, England, in 1946. I tried mightily but could find no images of him to enter into the digital archives of the web. He was a smart and diverse geologist, attending Trinity College, Cambridge, and winning important awards and scholarships. He was appointed assistant to the Woodwardian Professor of Geology at Cambridge in 1892, a position he kept until retirement. In 1901 he earned the Sedgwick Prize for his work on the rivers of East Yorkshire, wrote a book on the geology of the British Empire (much easier to do today!), and yet still found time to describe fossils in numerous papers.

The author of Eochonetes clarksvillensis is much better known to paleontologists of the Cincinnati region. It is August F. Foerste (1862-1936), who named Thaerodonta clarksvillensis in 1912. Foerste grew up and worked in the Dayton, Ohio, area, graduating from Denison University after publishing many papers as a student. He returned to Dayton after earning a PhD from Harvard, teaching high school for 38 years. When he retired he turned down a teaching position at the University of Chicago and instead worked at the Smithsonian Institution until the end of his life. He is one of the giants of the Cincinnati School of paleontology.

References:

Bauer, J.E. and Stigall, A.L. 2016. A combined morphometric and phylogenetic revision of the Late Ordovician brachiopod genera Eochonetes and Thaerodonta. Journal of Paleontology 90: 888-909.

Reed, F.R.C. 1917. The Ordovician and Silurian Brachiopoda of the Girvan District: Transactions of the Royal Society of Edinburgh 51: 795–998.

Wooster’s Fossil of the Week: A large trepostome bryozoan on a nautiloid conch (Upper Ordovician of northern Kentucky)

March 17th, 2017

This massive trepostome bryozoan, a solid lump of biogenic calcite, was collected earlier this week on the latest Team Cincinnati field expedition into the treasure-filled Upper Ordovician underlying and surrounding that city. Wooster students Matt Shearer, Luke Kosowatz and I are pursuing projects related to trepostome bryozoans and bioerosion (the biological destruction of hard substrates). The above specimen combines both these worlds, and more. Note the concavity at the base of the specimen. It comes from the Bellevue Formation (Katian) exposed on Bullitsville Road near the infamous Creation Museum (C/W-152).

Underneath the bryozoan colony (its zoarium) is this conical impression. It is an external mold of a straight nautiloid conch, the shell of a common squid-like cephalopod during the Ordovician. After the death of the nautiloid its empty tubular conch rested on the seafloor. This hard surface attracted the larvae of a variety of bryozoans that spread their calcitic zoaria (colonial skeletons) across the surface. Eventually one trepostome bryozoan species gained dominance over the space and occupied it all, growing into the large colony we see today. It even wrapped around the aperture of the conch (on the left) and grew a bit into the tube. Since the nautiloid conch was made of unstable aragonite, it long ago dissolved away, leaving an impression (external mold) in the stable calcite of the bryozoan.

How do we know there were earlier generations of bryozoans on this conch? We see them exposed upside-down on the surface of the external mold. Above we see the thin, branching cyclostome bryozoan Cuffeyella in the foreground, with a sheet of an encrusting trepostome bryozoan in the background. There are several other earlier bryozoans visible on this surface, revealing an ecological succession. There may be soft-bodied organisms preserved on this surface as well. This locality yielded the first described specimens of bioimmuration in the Ordovician (see Wilson et al., 1994).

There were other large trepostome bryozoans found in this same locality. I couldn’t resist cutting one in half to see what the inside looked like.

In this close view of the cross-section through the calcitic trepostome bryozoan we see numerous round holes drilled by some sort of worm seeking protective space so it could filter-feed. (In other words, it was not preying on the bryozoan.) The most intense boring of the specimen appears to have taken place just before and after the death of the colony. We know some borings were excavated into living bryozoan skeleton because the bryozoan formed reactive tissue around the intruder. The very tiny reddish-brown dots scattered in layers are “brown bodies“, the organic remnants of bryozoan polypides in their skeletal tubes (zooecia).

It has been a pleasure to return to the extraordinary Cincinnati fossils!

References:

Taylor, P.D. 1990. Preservation of soft-bodied and other organisms by bioimmuration—a review. Palaeontology 33: 1-17.

Wilson, M.A. 1985. Disturbance and ecologic succession in an Upper Ordovician cobble-dwelling hardground fauna. Science 228: 575-577.

Wilson, M.A., Palmer, T.J. and Taylor, P.D. 1994. Earliest preservation of soft-bodied fossils by epibiont bioimmuration: Upper Ordovician of Kentucky. Lethaia 27: 269-270.

Team Cincinnati heads home ahead of the storm (via Serpent Mound)

March 13th, 2017

Wooster, Ohio — Matthew, Mark and Luke (if only we had a John!) left the field a day early, hightailing it from Maysville, Kentucky, to Wooster today before a large storm system brought snow, ice and freezing rain (delightfully called a “wintry mix”). We made a couple of stops in the Whitewater Formation near West Union, Ohio, but did not collect because we couldn’t be sure of the stratigraphic context of loose specimens. On the way back north we visited the Serpent Mound National Historic Landmark near Peebles, Ohio. Matt and Luke are shown above freezing on the observation tower early in the morning. Not surprisingly, we had the place to ourselves.

Luke and Matt at the state marker for Serpent Mound.

There is no vantage on the ground from which you can see the entire serpent effigy mound. This is the view from the tower looking across the body towards the head.

Above is the coiled tail. There is considerable debate about when this elaborate mound was constructed. Some radiocarbon dating places it at around 300 BCE, therefore built by the Adena people. Other dating indicates it was made about 1070 CE by the Fort Ancient culture. The site is on an ancient (very ancient — Permian!) meteorite impact crater, an astrobleme. No evidence of this structure is directly visible at the site, but a geological survey of the bedrock shows incredible disruption. The late Dr. Frank Koucky, a geology professor at The College of Wooster, did considerable research on what was then known as the Serpent Mound Cryptoexplosion Structure. I had many field trips here with him as a student.

This is the storm we escaped late today. Our field areas are essentially in the pink wintry mix belt. We would have ended the trip early in any case, though, because Matt and Luke were such efficient field paleontologists that they filled all our available boxes with fossils (see below) and we visited all the critical sites we needed. Luke now drives to his home in New Jersey, and Matt drives home to California. Their labwork will begin when they return to campus from Spring Break. More details on their projects and discoveries then!

Team Cincinnati’s fossils ready to be unpacked, washed, sorted and studied.

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