Wooster Geologists

These exquisite little brachiopods are among the most abundant fossils in the Upper Ordovician of the Cincinnati area. My Invertebrate Paleontology students collected dozens of them from the Waynesville Formation on our field trip to Caesar Creek Lake last semester. Their ubiquity, though, doesn’t make them any less precious.
This is Zygospira modesta (Say in Hall, 1847). Above is a dorsal valve view of a single specimen. At the apex you can see a tiny round hole from which a fleshy pedicle extended to attach the brachiopod to a hard substrate.
Here is the ventral valve view. Zygospira is an atrypid brachiopod, meaning that its internal support (brachidium) for the filter-feeding lophophore is looped in a characteristic way, shown below.
The diagrams above are from Hall (1867) who named the genus Zygospira and wished to further distinguish it from other atrypid brachiopods.

The taxonomy of Zygospira modesta is a bit messy, as many early 19th Century species descriptions tended to be. It was apparently first named Producta modesta by Thomas Say (see below) but not actually published as such. James Hall described it as Atrypa modesta in 1847. Later in 1862 he named Zygospira as a new genus, making Z. modesta its type species but not indicating a type locality.
We met Thomas Say (1787-1834) earlier in this blog, recognizing him as the scientist who named Exogyra costata in 1820. He is shown above in an 1818 portrait. Say was a brilliant American natural historian. Among his many accomplishments in his short career, he helped found the Academy of Natural Sciences of Philadelphia in 1812, the oldest natural science research institution and museum in the New World. He is best known for his descriptive entomology in the new United States, becoming one of the country’s best known taxonomists. He was the zoologist on two famous expeditions led by Major Stephen Harriman Long. The first, in 1819-1820, was to the Great Plains and Rocky Mountains; the other (in 1823) was to the headwaters of the Mississippi. Along with his passion for insects, Say also studied mollusk shells, both recent and fossil. He was a bit of an ascetic, moving to the utopian socialist New Harmony Settlement in Indiana for the last eight years of his life. It is said his simple habits and refusal to earn money caused problems for his family. Say succumbed to what appeared to by typhoid fever when he was just 47.

References:

Copper, P. 1977. Zygospira and some related Ordovician and Silurian atrypoid brachiopods. Palaeontology 20: 295-335.

Hall, J. 1862. Observations upon a new genus of Brachiopoda. Report New York State Museum, Natural History 15: 154-155.

Hall, J. 1867. Note upon the genus Zygospira and its relations to Atrypa. Report New York State Museum, Natural History 20: 267-268.

Sandy, M.R. 1996. Oldest record of peduncular attachment of brachiopods to crinoid stems, Upper Ordovician, Ohio, USA (Brachiopoda; Atrypida: Echinodermata; Crinoidea). Journal of Paleontology 70: 532-534.

We have here another fossil collected by a Wooster student on the August 2015 College of Wooster Invertebrate Paleontology field trip to Caesar Creek Lake, Ohio. Eduardo Luna picked up this specimen of the tabulate coral Calapoecia huronensis (Billings, 1865) from the Waynesville Formation (Upper Ordovician). For some reason in all my years of working in the Upper Ordovician, I’ve not come across this coral species before. Eduardo had sharp eyes as you can see it is rather small. The circular tubes are corallites, each of which held a coral polyp in life. This particular coral is distinctive for its septal spines along the inside rim of each corallite, giving them a beaded appearance.

This is the underside of Eduardo’s coral. The corallites on the left side are eroded, showing the elongated septal spines that run lengthwise down their inside walls.

We met the author of C. huronensis, Elkanah Billings (1820-1876), earlier this year, but why not show the handsome Canadian again? He originally described this coral species in 1865. He was Canada’s first government paleontologist, and he very much looked the part. Billings was born on a farm near Ottawa. He went to law school and became a lawyer in 1845, but he gave up stodgy law books for the bracing life of a field paleontologist. In 1856, Billings joined the Geological Survey of Canada, eventually naming over a thousand new species in his career. The Billings Medal is given annually by the Geological Association of Canada to the most outstanding of its paleontologists.

References:

Billings, E. 1865. Notice of some new genera and species of Palaeozoic fossils. Canadian Naturalist and Geologist, New Series 2: 432–452.

Browne, R.G. 1965. Some Upper Cincinnatian (Ordovician) colonial corals of north-central Kentucky. Journal of Paleontology 39: 1177-1191.

Cox, I. 1936. Revision of the genus Calapoecia Billings. Bulletin of the National Museum of Canada 80: 1–48.

Jull, R.K. 1976. Review of some species of Favistina, Nyctopora, and Calapoecia (Ordovician corals from North America). Geological Magazine 113: 457-467.

This beautiful specimen was collected by Wooster student Eve Caudill on this year’s College of Wooster Invertebrate Paleontology field trip to Caesar Creek Lake, Ohio. It is the iconic trilobite Flexicalymene meeki (Foerste, 1910) from a soft, “buttery” shale in the Waynesville Formation (Upper Ordovician). This is one of the most common trilobite species in the world, and it has been photographed thousands of times, so I posed it at an unconventional, rakish angle. We are looking here at the cephalon (head) of the animal. I like the way the remnants of the enclosing sedimentary matrix cling to the low places, highlighting the bumps and ridges. The center of the cephalon shows the distinctive glabella with its side lobes. The stomach of the trilobite was housed underneath it. The two eyes are visible on either side of the glabella, the one on the right split by the slightly-open facial suture used for dividing its exoskeleton during molting (ecdysis).

This is a view of the pygidium (tail end) of the same Flexicalymene meeki specimen. It is tucked under the leading edge of the cephalon in the classic enrollment position. Trilobites likely enrolled for several reasons, but the primary one was almost certainly to affect a pill-bug-like defense against predators.

This is a side view of the enrolled trilobite. The articulated segments between the cephalon and pygidium constitute the thorax.We met the author of Flexicalymene meeki four years ago in this blog, so let’s visit him again. August F. Foerste (1862-1936) was one of the pioneers of Cincinnatian paleontology and stratigraphy. He grew up and worked in the Dayton, Ohio, area. Foerste went to Denison University where he was a very successful undergraduate, publishing several geological papers. He returned to Dayton after graduation with a PhD from Harvard, teaching high school for 38 years. When he retired he was offered a teaching position at the University of Chicago, but instead went to work at the Smithsonian Institution until the end of his life.

A final note from the Invertebrate Paleontology class this year: We were greatly assisted by two fantastic paleontological websites, one by Alycia Stigall at Ohio University called The Digital Atlas of Ordovician Life, and the other by Steve Holland at the University of Georgia titled The Stratigraphy and Fossils of the Upper Ordovician near Cincinnati, Ohio. Thank you to my most excellent and productive colleagues.

References:

Brandt, D.S. 1993. Ecdysis in Flexicalymene meeki (Trilobita). Journal of Paleontology 67: 999-1005.

Brett, C.E., Thomka, J.R., Schwalbach, C.E., Aucoin, C.D. and Malgieri, T.J. 2015. Faunal epiboles in the Upper Ordovician of north-central Kentucky: Implications for high-resolution sequence and event stratigraphy and recognition of a major unconformity. Palaeoworld 24: 149-159.

Esteve, J., Hughes, N.C. and Zamora, S. 2011. Purujosa trilobite assemblage and the evolution of trilobite enrollment. Geology 39: 575-578.

Evitt, W.R. and Whittington, H.B. 1953. The exoskeleton of Flexicalymene (Trilobita). Journal of Paleontology 27: 49-55.

Foerste, A.F. 1910. Preliminary notes on Cincinnatian and Lexington fossils of Ohio, Indiana, Kentucky, and Tennessee. Denison University Science Laboratories Bulletin 16: 17-87.

Frey, R.C. 1987. The paleoecology of a Late Ordovician shale unit from southwest Ohio and southeastern Indiana. Journal of Paleontology 61: 242-267.