Archive for October, 2011

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

October 30th, 2011

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.

George Davis (’64) gives the Thirty-First Annual Osgood Memorial Lecture

October 25th, 2011

WOOSTER, OHIO–We were greatly honored this evening to have one of our own, Dr. George Davis (Wooster ’64), present the 31st Annual Richard G. Osgood, Jr., Memorial Lecture. The Osgood Lectureship was endowed in 1981 by the three sons of Dr. Osgood in memory of their father, who was an internationally known paleontologist at Wooster from 1967 to 1981. We have had extraordinary experiences with visiting speakers through this lectureship, and tonight’s was one of the best.

Dr. Davis gave a public talk entitled “An evening’s geoarchaeological excursion to the Sanctuary of Zeus, Mt. Lykaion, The Peloponessos, Greece”. He described his stratigraphic and structural geological work in this fascinating region, which may have hosted the origins of the Zeus cult. It was (and still is) a thriving sports complex as well. Dr. Davis did interdisciplinary work as a geologist with his Brunton compass and as an archaeologist with a trowel — both iconic instruments of the professions.

Dr. Davis is a highly accomplished geologist with an outstanding reputation in teaching and research. After Wooster he earned a Master’s degree from the University of Texas at Austin, and then a PhD at Michigan. As a professor and chair at the University of Arizona for many years, he helped make that department into one of the best in the country. Dr. Davis has worked around the world and is best known for his analyses of geological structures in the Colorado Plateau and Basin & Range provinces. He is the author of a best-selling textbook in structural geology and has received many awards and honors. In July of next year he will become President of the Geological Society of America.
One of the joys of having our Osgood lecturer on campus is the traditional dinner with Wooster students and faculty before the talk. Dr. Davis had many geological stories to tell us, and he was a master at getting people around the table to talk about their motivations and geological dreams. A great evening was had by all!

Wooster’s Fossil of the Week: a medullosalean pteridosperm (Upper Carboniferous of northeastern Ohio)

October 23rd, 2011

It is time we had another fossil plant in this series. The above specimen is Neuropteris ovata Hoffmann 1826, a relatively common bit of foliage in the Upper Carboniferous of North America. This is a pteridosperm, more commonly known as a seed fern. They weren’t really ferns at all but fern-like plants with some of the first real seeds. They are usually reconstructed as trees, but were also known to be bushy or even like climbing vines.

The taxonomy (naming system) of fossil plants can be very complicated because different plant parts were given different names at different times. A single plant species, then, could have a list of names for its foliage, bark, roots, seeds, etc. The name Neuropteris usually thus refers to the leaves of this particular pteridosperm.

Neuropteris ovata is famous for its use in studies of the distribution of stomata on its leaf surfaces. Stomata, sometimes called guard cells, regulate gas exchange and moisture retention in vascular land plants. The density of stomata on N. ovata leaves in the Late Carboniferous may reflect changes in carbon dioxide levels and the expansion and contraction of tropical forests (Cleal et al., 1999).

Neuropteris ovata was named by Friedrich Hoffmann (1797-1836), a Professor of Geology at the University of Berlin. I wish I knew more about him because not only did he do considerable paleobotanical research, he was also well known for his work on volcanoes in Italy. You don’t see that combination very often!

References:

Beeler, H.E. 1983. Anatomy and frond architecture of Neuropteris ovata and N. scheuchzeri from the Upper Pennsylvanian of the Appalachian Basin. Canadian Journal of Botany 61: 2352-2368.

Cleal, C.J., James, R.M. and Zodrow, E.L. 1999. Variation in stomatal density in the Late Carboniferous gymnosperm frond Neuropteris ovata. Palaios 14: 180-185.

Hoffmann, F. 1826. Untersuchungen über die Pänzen-Reste des Kohlengebirges von Ibbenbühren und von Piesberg bei Osnabrück. Archiv für Bergbau und Hüttenwesen 13: 266-282.

Zodrow, E.L. and Cleal, C.J. 1988. The structure of the Carboniferous pteridosperm frond Neuropteris ovata Hoffman. Palaeontographica Abteilung Palaophytologie 208: 105-124.

Exploring the Silica Formation (Middle Devonian) in Northwestern Ohio

October 22nd, 2011

PAULDING, OHIO–There’s nothing like the stirring rings of 50 geologic hammers in the morning. Today I was a guest of the North Coast Fossil Club and my friend Brian Bade in a quarry exposing the Middle Devonian limestones and shales. There was frost on the ground when we began, but soon the sun rose and made it a delightful fall day of fossil collecting. Thank you to Brian and the NCFC for inviting me on their trip. I’ve spoken twice to the NCFC and they have been good friends since. It was my first visit to the highly fossiliferous Silica Formation (Middle Devonian), and I came away with a bag of treasures for my classes and research projects. Thank you also to the Lafarge Cement Quarry managers for facilitating this productive experience.

The Silica Formation is very well known for its abundant fossils, especially brachiopods, corals, trilobites, and bryozoans. I’ve wanted to examine the Silica for a long time because it has produced significant material for the hederelloid and microconchid projects I have been working on with my Polish, English and Estonian colleagues. For the first time I was able to collect my own specimens of each group, and to see the fossils in their geological context.

A quarry visit always starts with a sign-in process and a reading of the rules. Note the required reflective vests and hard hats. (I was very impressed that everyone knew my name until I realized it was emblazoned on the front of my helmet.)

A wall of the quarry. The thick gray unit is the Dundee Limestone; the thin dark sequence of mixed shales and limestones at the top is the Silica Formation. Both are Middle Devonian in age (Givetian).

Most of us figured out pretty quickly that the best places to collect fossils were in the large weathered blocks in irregular piles well away from the quarry walls. The soft Silica Formation shales erode quickly, releasing the hard calcitic fossils. Climbing around on these rocks is an acquired geological skill.

My paleontology students can tell even from this distant view what kind of coral this is in the top of the Dundee Limestone. (At least they better be able to by now!)

They can also identify the order to which this beautiful and delicate bryozoan belongs, I’m certain.

Bivalves and the spiriferid brachiopod Orthospirifer in the Silica Formation.

Finally, they tend to be overlooked in the excited search for trilobites and other shelled creatures, but there are also spectacular trace fossils in the Dundee Limestone.

 

 

Wooster Geology Heads to Wayne Elementary

October 21st, 2011

On Friday afternoon, a group of Wooster geologists participated in an educational outreach program at Wayne Elementary. Marge Forbush, an educator at Wayne always asks the department to come to her classroom twice a year. In the fall, we spend an afternoon talking to the students about volcanoes and earthquakes, while in the spring, we discuss fossils. This afternoon was particularly exciting. After a short introduction on volcanoes and earthquakes, the students then moved between 4 stations that we set up in the classroom. Geology majors at the college were each in charge of a station, fielding rapid-fire questions from the students. Lauren Vargo (’13) handled “Plate Tectonics”, while Nick Fedorchuk (’12) taught “Earthquakes”. Cameron Matesich (’14) showed the students “Intrusive Igneous Rocks”, and Sarah Appleton (’12) took charge of “Extrusive Igneous Rocks”. The Wayne Elementary students were excited to interact with department majors, and our majors did a fantastic job of teaching and mentoring.

The picture above shows everyone hard at work at their stations. Sarah (left in green), Nick (center in yellow), and Lauren (right in blue) had the attention of their students throughout the afternoon.

Cameron, above, is busy introducing the students to minerals and igneous rocks, which they were able to see close-up with the use of hand lenses.

How Fossils Saved Civilization: A National Fossil Day Talk

October 20th, 2011

WOOSTER, OHIO — National Fossil Day has now been in place for two years. Curiously enough, two Wooster alumnae, Erica Clites and Eva Lyon, have been critical organizers and promoters of this great event as Paleontology Interns with the National Park Service. It is sponsored by the NPS and the American Geosciences Institute (AGI). They even have an official National Fossil Day song! The College of Wooster is proud to be one of their academic partners on a list we hope will grow with the years.

As part of my contribution to National Fossil Day, I gave a talk to the Geology Club titled, “How Fossils Saved Civilization”. My title was inspired by “How the Irish Saved Civilization“, and like that book my tale had a bit of blarney in it. Nevertheless, I strongly believe that the proper understanding of fossils was one of the keys to the scientific revolutions of the 18th and 19th Centuries. Here’s to the beauty and wonder of fossils!

They’re back! Nursery school students visit the tree-ring lab

October 19th, 2011

WOOSTER, OHIO — This time it was the turn of Dr. Greg Wiles to host the The College of Wooster Nursery School children as they visited Scovel Hall and its world-famous Wooster Tree-Ring Laboratory. He had ambitious plans for the little tikes, from studying the details of ring widths to donning safety gear to see how the wood is prepared.

Dr.Wiles shows close-up computer images of tree-rings to future dendrochronologists.

 

The main challenge here was simply keeping all those hard hats on.

We very much enjoy these visits in the Geology Department, and every one of them has its delightful challenges! Just last month we had the same children studying rocks and minerals with Dr. Shelley Judge and a stout team of Wooster students.

Wooster’s Fossil of the Week: A carrier shell snail (Recent, Pacific Ocean)

October 16th, 2011

OK, it’s true: our Fossil of the Week is not actually a fossil. (The “Recent” in the title was a clue.) I bought this shell at the Wayne County Fair and it was so beautiful it just had to make the blog. (I paid $4 for it, which I think was quite a deal.)

What we have above is Xenophora pallidula (Reeve, 1842), commonly known as the Pallid Carrier Shell. It is a remarkable gastropod (snail) that ornaments its shell with “foreign” objects, usually other shells. (The genus name Xenophora means “foreign-bearing”.) They provide a nice sampling of the shelly debris surrounding their seafloor home.
The snail cements the items to the periphery of its shell as it grows, embedding the objects with its mantle into its aragonite. It selects dead shells and carefully rotates them with its foot and proboscis so that the concave side is upwards and the smaller end is attached. Attached snail shells thus have the aperture facing up, and clams have the inner side upwards as well. It takes almost two hours for a single object to be added to the shell, and up to 10 hours for the xenophorid snail to be confident enough to resume its normal life.

Why do xenophorids decorate their shells in this way? Apparently it is a kind of camouflage on a gravelly substrate. The long shells at the periphery of the shell also lift the shell above the substrate so that the snail’s body can extend inside a protective cage. The xenophorids can then peacefully feed on algae, diatoms and foraminiferans on the sediment. A curious habit they have which is rare among invertebrates: they dig holes in the sediment and bury their feces!

A glass sponge (Class Hexactinellida) attached to the top of Xenophora pallidula.

The genus Xenophora was named and described by the natural historian Johann Gotthelf Fischer von Waldheim (1771-1853). He was a German who specialized in marine invertebrates, insects, and fossils. von Waldheim studied under the famous Georges Cuvier in Paris, had a professorship in Germany, and then moved to Moscow in 1804 to become Director of the Natural History Museum at the University of Moscow. His work in Russia included the description of many new fossils, so we ultimately come back to paleontology!

Johann Gotthelf Fischer von Waldheim (1771-1853).

References:

Kreipl, K. and Alf, A. 1999. Recent Xenophoridae. ConchBooks: Hackenheim, Germany.

Ponder, W.F. 1983. A revision of the recent Xenophoridae of the world and of the Australian fossil species (Mollusca: Gastropoda). Memoirs of the Australian Museum 17: 1-126.

Sclerobionts and Extinctions: A Wooster Geologist Faculty Talk at the 2011 Geological Society of America Annual Meeting

October 12th, 2011

The last day of a professional meeting is very different from the first. At least half the attendees have gone home. Those that remain move a little slower and have that glazed look from late night dinners, too little sleep, and dreams of getting on that flight out of here. The convention staff is clearly oriented now towards the next event of cheerful conventioneers. (The “RAM SWANA” conference. I was so hoping this was about a mystical Indian guru, but instead it is a joint meeting of the “Recycling Association of Minnesota” and the “Solid Waste Association of North America”. I’ll give it a skip.)

My friend Paul Taylor and I organized a topical session on sclerobionts and mass extinctions, and we have the honor of ending the meeting this afternoon. With generous support from the Paleontological Society, we’ve brought in an international team of paleontologists who specialize in hard-substrate marine organisms, including Michał Zatoń of Poland, Silvio Casadio of Argentina, and Liz Harper of England. Our students Megan Innis and Caroline Sogot are participating as well. The audience may be the speakers themselves, but it will be enthusiastic. (Too bad we won’t get even a small fraction of the attention the pseudoscientific and embarrassing talk on the “Triassic kraken” received earlier in the meeting.)

I’ve started this entry with the first slide of the first talk, and ended it with our conclusions. We hope we’ve at least planted the seeds of a new topic in extinction studies. We’ve certainly had fun getting this diverse group of scientists together in one room.

And yes, we are also dreaming of that flight home!

Posters Round Two at GSA – Minneapolis

October 11th, 2011

 

Sarah Appleton presents her research in Glacier Bay National Park and Preserve. Her IS topic Tree-Ring Dating of the Glacial History of Wachusett Inlet, Glacier Bay was part of a special session honoring Dr. David Michaelson (U. Wisconsin – Madison) a long time worker in Glacier Bay.

Andrew Collins presents his work on The Use of Geophotography as a Permanent Resource in Higher Education - this is a collaborative project that Andrew is doing with Drs. Judge and Wiles and The College of Wooster librarians – Marsha Bansberg and Jessica Clemons. The database has gone live and can be found here. In the future all those trips to Spangler and other field sites around Wooster will be archived at this site. If alumni have some photos in their collection they would like to contribute to the effort, that would be greatly appreciated.

Lindsey Bowman presented her geochemical data to the geologists. He poster describes results of her ongoing IS work with Dr. Meagen Pollock in Iceland. Her poster is entitled: Geochemical and Field Relationships of Pillow and Dike Units in a Subglacial Pillow Ridge, Undirhlithar, Southwest Iceland.

Dr. Shelley Judge leads a lively discussion of her work summarizing 65 Years of Pedagogical Scaffolding and Sequencing in the Sanpete Valley of Central Utah – although it sounds like a series of structural geology terms, Dr. Judge’s poster was about assessment. In addition to being a leader in the field of structural geology, Dr. Judge is a leader in learning assessment, which makes her Chair very happy.

 

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