Archive for July, 2012

Wooster’s Fossil of the Week: fusulinids (Upper Carboniferous of Kansas)

July 8th, 2012

They look like little footballs, at least the American variety of football. Fusulinids (the name indicating the fusiform shape) are about the size and shape of wheat grains. They were marine protists (single-celled eucaryotes) that lived from the late Early Carboniferous to the end of the Permian Period. Fusulinids are foraminiferans of the Superfamily Fusulinoidea named by Valerïan Ivanovich Möller (Imperial School of Mines, St. Petersburg) in 1878. They are critical index fossils for the Late Paleozoic, and I knew them intimately during my dissertation work in southern Nevada.

The shell of a fusulinid is very complex. It is made of a granular calcite wrapped along the axis of the football in a series of chambers with internal walls. Each coil wrapped completely over the earlier coils, making the shells involute. They are most commonly studied in section to reveal the internal complexity.
Cross-section of a fusulinid (Triticites) from the Permian of Iowa.

Fusulinid evolution was dramatic for a single-celled group. The earliest varieties were very small (one or two millimeters in length), and the later ones up to five centimenters long. Their internal features also increased in complexity, making each successive new species very easy to identify. This is why they are such good indications of geological time intervals. It is this biostratigraphic value that proved most useful to me as a young graduate student working in what seemed to me to be virtually featureless Carboniferous limestones.

References:

Hageman, S.A., Kaesler, R.L. and Broadhead, T.W. 2004. Fusulinid taphonomy: encrustation, corrasion, compaction, and dissolution. Palaios 19: 610-617.

Möller, V.I., von. 1878. Die Spiral-gewundenen Foraminiferen des russischen Kohlenkalks. Mémoires de l’académie impériale des sciences de St-Pétersbourg, VII Série, Tome XXV, No. 9 et dernier.

Ross, C.A. 1967. Development of fusulinid (Foraminiferida) faunal realms. Journal of Paleontology 41: 1341-1354.

Stevens, C.H. and Stone, P. 2007. The Pennsylvanian–Early Permian Bird Spring carbonate shelf, southeastern California: Fusulinid biostratigraphy, paleogeographic evolution, and tectonic implications. Geological Society of America Special Paper 429, 82 p.

Crinoid hunting in ancient Baltica

July 7th, 2012

KURESSAARE, ESTONIA–Bill Ausich (Ohio State University) and I have a grant from the National Geographic Society to study the “origination and evolution of Middle Paleozoic crinoids on the Baltica paleocontinent“. Bill is the prime mover behind this project as one of the world’s experts on crinoids, and probably the expert on Silurian crinoids. My job is to help with the paleoecology and stratigraphic context for these crinoids. We have one paper in press now on Estonian crinoids with our colleague Olev Vinn of the University of Tartu. The above photo shows our team this morning looking for crinoids in the Ninase Member of the Jaani Formation at the Undva Cliff on the northwestern tip of Saaremaa Island (N 58.51679°, E 021.91727°).

The full team includes Wooster students Jonah Novek and Richa Ekka (introduced before), Ohio State University graduate students Mark Peter and Alyssa Bancroft, and OSU undergraduate Jeff Thompson. Along with finding crinoids, the Wooster students will also be developing their Independent Study field projects. This is why our work is also supported by the Wengerd Fund at The College of Wooster.

Today we met Olev Vinn (and his wife Ingrid and two delightful children, Sigrid and Erik) and explored three outcrops looking for crinoids, especially their elusive calices (essentially their heads). Above is a calyx of Eucalyptocrinites showing partition plates. We found many more such beauties, especially at Undva Cliff.

Rain is going to be a fact of field life in the next week at least. The weather can apparently change rapidly on the Baltic coast. The above storm appeared to the west of us in mid-morning at Undva Cliff. Since the wind was blowing to the west, it didn’t seem an issue. The wind direction changed 180°, though, and quickly brought the deluge upon us. We ran back to our vehicles but were completely soaked. Lesson learned!

Our second outcrop was the Ninase Member again on the western shore of Tagalaht Bay at a place called Kuriku Cliff (N 58.50282, E 022.01284). You can see us above scattered along the cliff face.

The preservation of the fossils at Kuriku Cliff is mixed. Some calcitic forms are exquisite, especially brachiopods and crinoids. Others, like the favositid coral above, are recrystallized. In this case the corallites filled with calcite and then dissolved, leaving an odd kind of internal mold.

Our last outcrop was Kogula Quarry (N 58.28589°, E 022.26053°), where road gravel is made by progressively crushing limestones from the Silurian (Ludlow) Paadla Formation. Saturday was a good time to visit this quarry because it was closed and not operating. We found many fossils here, especially mollusks. The crinoids, though, were only rare bits and pieces.

Except for that morning drenching, it was a very good paleontological day. The Wooster students have been well introduced to Silurian limestones in general and Saaremaa stratigraphy in particular. Tomorrow we will see what Olev says is the only outcrop on Saaremaa I have not visited. That will complete our tour and we can then begin to do our detailed work. Now we know to run for cover as soon as we feel the wind quickly change!

 

Silurian limestone under our feet

July 6th, 2012

KURESSAARE, ESTONIA–The 2012 Wooster Estonia expedition had its first official time in the field this afternoon. Jonah, Richa and I traveled the short distance from Kuressaare to the historical Sõrve peninsula in the extreme southwest of Saaremaa. There we explored the Äigu Beds in the Kaugatuma Formation exposed along the peninsula’s northwest coast. I know this place well from several visits, and it was the site of Palmer Shonk’s Independent Study project. The limestone here is mostly a high-energy encrinite (a rock made almost entirely of crinoid fragments) with many elaborate crinoid root systems in place showing the arrangement of a “crinoid forest”. Pictured above is a limestone bedding plane with two primary axes of the roots  (holdfast) of the genus Enallocrinus. The interior sediment has eroded away so that you can see the holes where “rootlets” emerged to penetrate the surrounding sediment.

Richa and Jonah on the swampy northwest side of the peninsula with the Kaugatuma Cliff exposed in the background.

Our liberally-educated students are here examining the surface of a granitic boulder brought here from Sweden by the last glaciation and dropped as an erratic. Of course, it is not the igneous rock that excites them — it’s the multicolored  lichens on it!

This project is funded by a grant from the National Geographic Society and the Wengerd Fund of The College of Wooster. Tomorrow we will introduce you to the Ohio State University team members and more details about our work and goals. We are very grateful for this research opportunity. We are also very pleased with the spectacular weather. Sunny and 26°C today.

 

Wooster Geologists return to Estonia

July 6th, 2012

KURESSAARE, ESTONIA–It took longer than we expected, but three Wooster geologists and four colleagues from Ohio State University are finally on the island of Saaremaa and ready for our fieldwork in the Silurian limestones along the shores here and on the smaller island of Hiiumaa to the north. We had a missed connection which delayed us a day in Tallinn, and everywhere we went our reservations were difficult to find, but it has at last worked out. Above you see Richa Ekka and Jonah Novek, two Wooster seniors who will be studying the Silurian sections for their Independent Study theses. Behind them is Moon Sound between the Estonian mainland and Muhu Island as viewed from a car ferry. Richa and Jonah are part of a long tradition of Wooster students who have worked in Estonia, some of whom you can meet by clicking our Estonia tag to the right.

Now we’re off to buy some lunch and take advantage of the fantastic weather to see some rocks. Much more will follow!

The view from my hotel room of Kuressaare Castle. Nice, eh?

Wooster’s Fossils of the Week: Wiggly little foraminiferans from the Middle Jurassic of southern England

July 1st, 2012

These shell fragments are of the oyster Praeexogyra hebridica var. elongata, and I picked them up long ago from a remarkable unit made almost entirely of them. It is the Elongata Bed at the base of the Frome Clay (Middle Jurassic) near Langton Herring in Fleet Lagoon, Dorset, England. (See House (1993) for more details, and this site has a nice geological map.) Nearly every oyster piece is covered with elongated, flaky white encrusters easily overlooked. They are attached foraminiferans known as Vinelloidea crussolensis Canu, 1913. (I labelled the specimens with the better-known name “Nubeculinella Cushman, 1930″ when I collected them. Voigt (1973) had earlier shown that this genus is a junior synonym of Vinelloidea. I should have known better.)

Vinelloidea is in the Order Miliolida of the Foraminifera. It is a very common sclerobiont in shallow water Jurassic and Cretaceous deposits, especially in western Europe. Curiously, I’ve not yet seen it in the Jurassic or Cretaceous of Israel, and I’ve looked very hard at the encrusting faunas there. Vinelloidea grew as a series of glassy chambers across shells, pebbles and hardgrounds (Reolid and Gaillard, 2007; Zaton et al., 2011). When the conditions were right, as they were in the Middle Jurassic in southern England, it could be one of the most abundant encrusting organisms in life’s history.

References:

Canu, F. 1913. Contribution à l’étude des Bryozoaires fossiles XIII. Bryozoaires jurassiques. Bulletin de la Société géologique de France, série 4, 13:267-276.

Cushman, J.A. 1930. Note sur quelques foraminifères jurassiques d’Auberville (Calvados). Bulletin de la Société linnéenne de Normandie, série 8, vol. 2 (1929): 132-135.

House, M.E. 1993. Geology of the Dorset Coast. Geologists Association Guide No. 22. 2nd edition, 164 pages.

Reolid, M. and Gaillard, C. 2007. Microtaphonomy of bioclasts and paleoecology of microencrusters from Upper Jurassic spongiolithic limestones (External Prebetic, southern Spain). Facies 53: 97-112.

Voigt, E. 1973. Vinelloidea Canu, 1913 (angeblich jurassische Bryozoa Ctenostomata) = Nubeculinella Cushman, 1930 (Foraminifera). Paläontologische Abhandlungen 4: 665-670.

Zaton, M., Machocka, S., Wilson, M.A., Marynowski, L. and Taylor, P.D. 2011. Origin and paleoecology of Middle Jurassic hiatus concretions from Poland. Facies 57: 275-300.

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