Archive for December, 2012

Wooster Geologist in Ireland

December 15th, 2012

IrishFlag121512DUBLIN, IRELAND — In a very quick transition from grading final exams in Wooster yesterday morning, I find myself now in downtown Dublin. I flew in last night to attend the 56th Annual Meeting of the Paleontological Association. I’ve been a member of this wonderful organization since 1985 — in fact, I’m one of the North American Representatives — and I love my rare visits to the main meetings. They are held throughout Europe to recognize the international base of the Palaeontological Association, with an emphasis on its European core. I am here representing the Paleontological Society in my role as Secretary. I am looking forward to meetings with my paleontologist colleagues, and to learning more about our craft and passion.

DublinPostOffice121512Since my first meeting is tomorrow morning, I spent some time looking at some of the historical places in the Dublin City Centre. Most impressive to me is the evocative Post Office, site of the failed Easter Rising by Irish nationalists in 1916. Above is the post office today. Below is the burned-out shell after the 1916 battle with British troops. Bullet scars are still visible in the stonework.

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FourCourts121512The Four Courts, Ireland’s main court complex. The original structure was built in the 18th Century. The River Liffey is in the foreground.

Wooster’s Fossil of the Week: A horn coral from the Upper Ordovician of Indiana

December 9th, 2012

This week’s fossil is a very common one from the Whitewater Formation (Richmondian, Upper Ordovician) exposed near Richmond, Indiana. It was collected, along with hundreds of other specimens, during one of many Invertebrate Paleontology field trips to an outcrop along a highway. The fossil is Grewingkia canadensis (Billings, 1862), a species my students know well because many made acetate peels of cross-sections they cut through it.

Grewingkia canadensis belongs to the Order Rugosa, a group commonly called the “horn corals” because their solitary forms (as above) have a horn-like shape. Children often think they are dinosaur teeth! It is so common in Richmondian rocks that it is sometimes used to indicate current direction. Its robust skeleton provided attachment space to many encrusting organisms, and it often has multiple borings in its thick calcite theca.

We believe that the rugose corals lived much like corals today. They sat partially buried in the sediment with the wide end of the skeleton facing upwards. A polyp sat inside the cup-shaped opening, spreading its tentacles to catch small organisms swimming by.

Grewingkia canadensis has a complicated taxonomic history. It is likely also known as Streptelasma rusticum, Grewingkia rustica, Streptelasma vagans, Streptelasma insolitum, and Streptelasma dispandum. G. canadensis is characterized by cardinal and counter septa (the vertical partitions inside the coral skeleton) that are longer than the other major septa throughout ontogeny (growth).
The handsome man shown above is, of course, a paleontologist. This is Elkanah Billings (1820-1876), Canada’s first government paleontologist and the one who named Grewingkia canadensis. (He originally placed it in the genus Zaphrentis.) Billings was born on a farm near Ottawa. He went to law school and became a lawyer in 1845. But he loved fossils and in 1852 founded a journal called the Canadian Naturalist (and Geologist). In 1856, Billings left the law and joined the Geological Survey of Canada as its first paleontologist. He named over a thousand new species in his career, and is best known for describing the first fossil from the Ediacaran biota — a critical time in life’s early history. The Billings Medal is given annually by the Geological Association of Canada to the most outstanding of its paleontologists.

References:

Billings, E. 1862. New species of fossils from different parts of the Lower, Middle, and Upper Silurian rocks of Canada. Paleozoic Fossils, Volume 1, Canadian Geological Survey, p. 96-168.

Elias, R.J. and Lee, D.J. 1993. Microborings and growth in Late Ordovician halysitids and other corals. Journal of Paleontology 67: 922-934.

Elias, R.J., McAuley, R.J. and Mattison, B.W. 1987. Directional orientations of solitary rugose corals. Canadian Journal of Earth Sciences 24: 806-812.

Familiar Faces at AGU 2012

December 3rd, 2012

San Francisco, CA – The annual meeting of the American Geophysical Union is the largest earth science conference in the world.

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With more than 20,000 attendees and about 3000 posters per day, you’re bound to bump into someone you know. Today, I ran into Wooster alum Jesse Davenport (’11). You may remember his senior I.S. adventures in Montana, working on 2 billion year old sheared igneous and metamorphic rocks. Jesse is currently a graduate student at Notre Dame and has shifted his focus to more recent (~80 million years old) basalts – a topic that I can finally relate to!

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Jesse is studying the compositions and textures of plagioclase and olivine crystals in basalts from the Detroit Seamount to better understand magmatic processes at ocean islands. (See a more complete explanation in his AGU abstract). It’s always fun to catch up with alumni who travel diverse paths yet have the common Wooster experience. If we’re lucky, Jesse will come to Wooster to share his research and experiences with GeoClub sometime this spring.

Wooster’s Fossils of the Week: Shark teeth! (Upper Cretaceous of Israel)

December 2nd, 2012

This week’s set of exquisite fossils is presented in honor of Andrew Retzler (’11) who has just had his Senior Independent Study thesis at Wooster published in the journal Cretaceous Research: “Chondrichthyans from the Menuha Formation (Late Cretaceous: Santonian–Early Campanian) of the Makhtesh Ramon region, southern Israel“. The above beauties are a mix of Scapanorhynchus teeth found in the southwestern portion of Makhtesh Ramon during Andrew’s study in the summer of 2010. We were ably assisted by Micah Risacher and Yoav Avni with these collections.

Andrew identified at least eight shark species and two other fish species in the Menuha Formation around Makhtesh Ramon. Most of the teeth are from a soft yellowish chalk with relatively few other fossils (mostly oysters, echinoids, foraminiferans and traces). They show that the Menuha was deposited in a shallow, open-shelf environment on the flanks of the developing Ramon anticline. So, they not only provide new information about Cretaceous sharks in the Middle East, they help sort out a complex stratigraphic-structural problem.

Well done, Andrew! (Andrew is currently a graduate student at Idaho State University. He is working on the Late Devonian Alamo Impact Event in Nevada with Dr. Leif Tapanila.)

Tooth of the shark Cretalamna appendiculata. Composite photo by Andrew Retzler.

Scapanorhynchus rapax, another shark species. Composite photo by Andrew Retzler.

An elegant Scapanorhynchus texana tooth.

Looking south at one of the productive exposures of the Menuha Formation (shown as the red dot) at Makhtesh Ramon. This is one of those amazing Google Earth images.

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