The first Wooster Geology student posters at GSA 2012

November 4th, 2012

CHARLOTTE, NORTH CAROLINA–The brave souls Jonah Novek (’13) above and Kit Price (’13) below were the first Wooster students to present their posters at the 2012 Geological Society of America meeting. Jonah worked in Estonia this past summer on Early Silurian recovery faunas in the Hilliste Formation on Hiiumaa Island. You can read his abstract directly here, and you can recall his field adventures by searching for “Jonah” in this blog. Kit collected Upper Ordovician cryptic sclerobiont fossils in Indiana in the late summer. Her abstract is here, and you can see her work in this blog by searching for “Kit“. Jonah and Kit started off our GSA presentation experience with confidence and joy.

Wooster’s Fossils of the Week: Giant ostracods (Silurian of Estonia)

October 7th, 2012

During our Estonian expedition this summer, Richa Ekka (’13) chose as her Independent Study project focus the Soeginina Beds (lowermost Ludlow, Upper Silurian) of the Paadla Formation exposed in southeastern Saaremaa Island. These carbonate sediments, mostly dolomitized, were deposited in very shallow conditions — so shallow that in some places we have syneresis cracks and halite crystal molds. I expected the fossils to be mostly stromatolites and rare traces. We were pleasantly surprised to also find, though, a bed with numerous valves of the giant ostracod Herrmannina Kegel 1933 (shown above). I should have guessed that the hardy and extraordinarily successful ostracods would have been present.

At first we thought that these slightly-recrystallized shells must be bivalves (clams) because of their relatively large size (up to 25 mm long). But we didn’t see the typical bivalve muscle scars or hinging teeth and sockets. They had to be ostracods — but so big? The typical ostracod valve, shown below, is two mm or less in length. These Silurian examples are over 10 times that size. It would be like me meeting my 60-foot equivalent. Turns out that Herrmannina is known for its gigantism in the ostracod world — and it is not even the largest.

Cyamocytheridea sp. from the Eocene of Nederokkerzeel, Belgium. (Public Domain, Wikimedia.) This is the typical small size for an ostracod.
Today the ostracods, members of the Phylum Arthropoda, have over 8000 living species in both fresh and marine waters. Most crawl or burrow into sediments (that is, most are vagrant benthic epifaunal and infaunal), and a few are suspended in the water column (planktic). They have a wide range of feeding habits, from filter-feeding and deposit-feeding to herbivory and carnivory. (This is a key to their survival from the Early Paleozoic to today.) The living ostracod above shows that they are essentially a large head with several pairs of appendages inside two hinged valves. (The image is public domain from Anna33 at Wikipedia.) Their sex life is astonishing: ostracods have the largest sperm of any animals in both relative and absolute measures. Ostracod sperm are often ten times the length of the male body. (No, I don’t know how that works!)

Herrmannina is in the Order Leperditicopida of the Class Ostracoda. This genus was named in 1933 by Wilhelm Kegel (1890-1971), a geologist in the Preussische Geologische Landesanstalt of Berlin, Germany, who specialized in the Devonian and Carboniferous systems. I couldn’t find out much more about Dr. Kegel, but did stumble across an uncredited, undated low-resolution photo of him above. A fuzzy face from our paleontological past!

References:

Abushik, A. 2000. Silurian-earliest Devonian ostracode biostratigraphy of the Timan-Northern Ural Region. Proceedings of the Estonian Academy of Sciences, Geology 49: 112-125.

Belak, R. 1977. Ontogeny of the Devonian Leperditiid ostracode Herrmannina alta. Journal of Paleontology 51: 943-952.

Kegel, W. 1933. Zur Kenntnis palaozoischer Ostrakoden 3, Leperditiidae aus dem Mitteldevon des Rheinischen Schiefergebirges. Preussischen Geologischen Landesanstalt, Jahrbuch fur das Jahr 1932, Bd. 53, p. 907-935.

Kesling, R.V. 1958. A new and unusual species of the ostracod genus Herrmannina from the Middle Silurian Hendricks Dolomite of Michigan. Contributions, Museum of Paleontology, The University of Michigan 14, No. 9: 143-148.

Putzer, H. 1971. Wilhelm Kegel. Geologisches Jahrbuch 89: xiii-xxii.

Vannier,J., Wang, S.Q., and Coen, M. 2001. Leperditicopid arthropods (Ordovician – Late Devonian): Functional morphology and ecological range. Journal of Paleontology 75: 75-95.

Wooster’s Fossil of the Week: a twisted little crinoid (Lower Silurian of Estonia)

September 9th, 2012

This week’s fossil is a tiny little crinoid with an odd shape. Calceocrinus balticensis (shown above with the scale bar as one millimeter) is a new species from the Lower Silurian (Llandovery) of Hiiumaa, western Estonia. It is part of a series of new crinoid taxa described in the most recent issue of Acta Palaeontologica Polonica by Ausich et al. (2012). All that geological work in Estonia by Ohio State and Wooster geologists is resulting in several paleontological publications, all with the collaboration of our friend Olev Vinn at the University of Tartu, Estonia.

The western Estonian island of Hiiumaa where our little crinoid was found. (Image courtesy of Google Maps.)

Calceocrinus balticensis Ausich, Wilson and Vinn, 2012 (to give its full and glorious name) is unusual because its crown (the filter-feeding “head” of the crinoid) is recumbent on the column (the “stem”). In the images above you can see the column as a series of disks on their sides at the bottom of the view. The crown is the set of larger plates attached to the top of the column, from which there are several arms extending to the right. This new species is the first of its genus from the paleocontinent Baltica. It had sister species in North America on what became Anticosti Island in eastern Canada (see Ausich and Copper, 2010).

Calceocrinids (Order Calceocrinida Ausich, 1998) lived very close to the seafloor. The column of an individual, which in other crinoids holds the crown far off the substrate, lay horizontally along the bottom. The crown was hinged at its base so that it could be elevated perpendicular to the stem with the arms spread wide to filter organic material from the water. During non-feeding times the crown would lie inconspicuous on the bottom. This crinoid literally had a very low profile compared to its showy cousins.

Now, though, the shy little Calceocrinus balticensis gets a moment of exposure and formal admission to the roll call of life’s species.

References:

Ausich, W.I. 1998. Phylogeny of Arenig to Caradoc crinoids (Phylum Echinodermata) and suprageneric classification of the Crinoidea. The University of Kansas Paleontological Contributions, n.s. 9, 36 pp.

Ausich, W.I. and Copper, P. 2010. The Crinoidea of Anticosti Island, Québec  (Late Ordovician to Early Silurian). Palaeontographica Canadiana 29, 157 pp.

Ausich, W.I., Wilson, M.A. and Vinn, O. 2012. Crinoids from the Silurian of western Estonia. Acta Palaeontologica Polonica 57: 613-631.

Wooster’s Fossils of the Week: A stromatoporoid-stromatolite combination (Upper Silurian of Saaremaa Island, Silurian)

July 22nd, 2012

There are two common fossil types that begin with “strom” and look roughly alike to the untrained eye. One is the stromatoporoid, which is a calcareous sponge, and the other is the stromatolite, which is a layered structure produced by photosynthetic bacteria. I hadn’t seen them together until our expedition to the Silurian of Estonia last summer. Wooster senior Nick Fedorchuk (’12) collected the specimen above at his outcrop of limestones and dolomites just above the Wenlock/Ludlow Boundary along Soeginina Cliff, Saaremaa. (In the rock sequence Richa Ekka is now studying.) We thought it was simply a stromatolite until he cut it to show that the base was a stromatoporoid.
“Stroma” is Greek for a bed or layer. Both stromatolites and stromatoporoids have horizontally laminated structures. The “lite” in stromatolite means rock, so a stromatolite is literally a “layered rock”. They are accretionary structures made by mostly cyanobacteria that collect and bind fine sediment into thin layers, usually in very shallow waters. Often the bacteria make their own calcareous cement for these laminae as a byproduct of photosynthesis. They’ve been doing this for a long time: the earliest known fossils are 3.5 billion-year-old stromatolites.

Stromatoporoids are very different. The “poroid” refers to their semi-porous skeletal layers, which are separated from each other by minuscule pillars. Their peak of abundance was in the Silurian and Devonian Periods, but they survived all the way up into the Cretaceous. They made significant reefs in the Paleozoic, often more common than the corals back then. We believe that they were a type of sponge (Phylum Porifera) with a thin layer of soft tissue on the exterior layer filter-feeding in the typical sponge manner.

Stromatolites are more common in sediments formed in very shallow, warm marine waters with elevated salinity; stromatoporoids liked more normal marine conditions. Finding the stromatolite on top of the stromatoporoid here means that either the environment changed between the two (shallowing, likely), or that the stromatoporoid was dislodged from more offshore waters during a storm and washed into a shallow lagoon, becoming a substrate for stromatolitic growth.

Curiously, there was a suggestion in 1990 by Kaźmierczak and Kempe that stromatoporoids ARE stromatolites. They pointed out that precipitation features in modern stromatolites can be very complex, producing features that resemble those of ancient stromatoporoids. This idea gained no traction, though, and most paleontologists are satisfied that these two types of “strom” have very different origins.

References:

Akihiro, K. 1989. Deposition and palaeoecology of an Upper Silurian stromatoporoid reef on southernmost Gotland, Sweden. Geological Journal 24: 295-315.

Kaźmierczak, J. and Kempe, S. 1990. Modern cyanobacterial analogs of Paleozoic stromatoporoids. Science 250, no. 4985, pp. 1244-1248.

Lebold, J.G. 2000. Quantitative analysis of epizoans on Silurian stromatoporoids within the Brassfield Formation. Journal of Paleontology 74: 394-403.

Segars, M.T. and Liddell, W.D. 1988. Microhabitat analyses of Silurian stromatoporoids as substrata for epibionts. Palaios 3: 391-403.

Soja, C.M., White, B., Antoshkina, A., Joyce, S., Mayhew, L., Flynn, B. and Gleason, A. 2000. Development and decline of a Silurian stromatolite reef complex, Glacier Bay National Park, Alaska. Palaios 15: 273-292.

Vinn, O. and Wilson, M.A. 2010. Endosymbiotic Cornulites in the Sheinwoodian (Early Silurian) stromatoporoids of Saaremaa, Estonia. Neues Jahrbuch für Geologie und Paläontologie, Abh., v. 257: p. 13–22.

Analysis of a Rhuddanian (Llandovery, Lower Silurian) sclerobiont community in the Hilliste Formation on Hiiumaa Island, Estonia: a hard substrate-dwelling recovery fauna — An abstract submitted to the Geological Society of America for the 2012 annual meeting

July 19th, 2012

Editor’s note: The Wooster Geologists in Estonia this summer wrote abstracts for posters at the Geological Society of America Annual Meeting in Charlotte, North Carolina, this November. The following is from student guest blogger Jonah Novek in the format required for GSA abstracts:

Analysis of a Rhuddanian (Llandovery, Lower Silurian) sclerobiont community in the Hilliste Formation on Hiiumaa Island, Estonia: a hard substrate-dwelling recovery fauna

NOVEK, Jonah M., WILSON, Mark A., EKKA, Richa N., Department of Geology, The College of Wooster, Wooster, OH 44691 USA; AUSICH, William I., School of Earth Sciences, The Ohio State University, Columbus, OH 43210 USA; VINN, Olev, Department of Geology, University of Tartu, Ravila 14A, 50411 Tartu, Estonia

The Hilliste Formation on the island of Hiiumaa, western Estonia, is a Rhuddanian (Llandovery, Lower Silurian) sequence of limestones and shales.  It represents some of the earliest Silurian rocks on the paleocontinent of Baltica. The depositional system was tropical and shallow marine with tempestites indicated by overturned and broken corals and stromatoporoids. This unit contains a recovery fauna from the Ordovician Mass Extinction. Major taxa in the Hilliste Formation include crinoids, trilobites, bryozoans, corals, stromatoporoids, gastropods, and brachiopods. Sclerobiont communities (organisms that lived on or within hard substrates) have not yet been described from Rhuddanian faunas. The Hilliste Formation contains many encrusters and a few borings on skeletal substrates (primarily corals and crinoid stems). These sclerobionts include at least three kinds of crinoid holdfasts, cornulitids, sheet-like bryozoans, runner-type bryozoans, erect bryozoan holdfasts, and auloporid corals. Most if not all of these sclerobionts inhabited dead substrates. We studied the Hilliste Formation in a small quarry near the village of Hilliste on Hiiumaa. Numerous encrusted and bored specimens were collected for analysis of sclerobiont occurrences in this rare example of a Rhuddanian hard substrate community. These encrusters and borings, along with the macrofauna, have a distinct Late Ordovician aspect.

Stratigraphy and paleoenvironment of the Soeginina Beds (Paadla Formation, Lower Ludlow, Upper Silurian) on Saaremaa Island, Estonia — An abstract submitted to the Geological Society of America for the 2012 annual meeting

July 19th, 2012

Editor’s note: The Wooster Geologists in Estonia this summer wrote abstracts for posters at the Geological Society of America Annual Meeting in Charlotte, North Carolina, this November. The following is from student guest blogger Richa Ekka in the format required for GSA abstracts:

Stratigraphy and paleoenvironment of the Soeginina Beds (Paadla Formation, Lower Ludlow, Upper Silurian) on Saaremaa Island, Estonia

EKKA, Richa N., WILSON, Mark A., NOVEK, Jonah M., Department of Geology, The College of Wooster, Wooster, OH 44691 USA; VINN, Olev, Department of Geology, University of Tartu, Ravila 14A, 50411 Tartu, Estonia

The Soeginina Beds in the Paadla Formation on the island of Saaremaa, western Estonia, are a Lower Ludlow (Upper Silurian) sequence of dolostones, marls, and stromatolites. They represent rocks just above the Wenlock/Ludlow boundary, which is distinguished by a major disconformity that can be correlated to a regional regression on the paleocontinent of Baltica. We interpret the depositional environment of the Soeginina Beds as having been a hypersaline lagoon. Our evidence includes halite crystal molds, oscillation ripples, eurypterid fragments, stromatolites, ostracods, gastropods, Chondrites trace fossils, intraclasts and oncoids. Nautiloid conchs are common, probably because storm currents washed them in. We measured two sections of the Soeginina Beds at Kübassaare, eastern Saaremaa, western Estonia. The beds in one section are virtually horizontal; in the second they are steeply dipping, probably because of Pleistocene glacial ice overpressure. The beds begin with fine-grained dolostone and end with large, well-preserved domical stromatolites. The equivalent section at Soeginina Pank in western Saaremaa (about 86 kilometers away) has larger oncoids, branching coral fragments, and smaller stromatolites. It is also more heavily dolomitized. We interpret these differences as showing the western Soeginina Beds were deposited in slightly deeper, less saline waters than those in the east at Kübassaare.

A museum visit: Institute of Geology at Tallinn University of Technology

July 17th, 2012

TALLINN, ESTONIA–This morning Bill Ausich and I examined fossils in the collections of the Institute of Geology at Tallinn University of Technology (the cool exterior of which is shown above). The Chief Curator, Ursula Toom, generously came in from her vacation to show us some important Ordovician and Silurian crinoid specimens, as well as assemblages from the Lower Silurian throughout Estonia. We had an excellent time looking at gorgeous fossils in a classic museum. (We were here in 2009 with Rob McConnell and Palmer Shonk as well.)

It must be an interesting place if they bolt a rock up off the ground in front!

Bill is here looking at crinoids Ursula set aside for us to examine. Note his use of an iPad for taking notes and images, just like Wooster geologists did last year at Ohio State. Bill carries his entire pdf library with him on his iPad, and makes many annotated images of museum specimens.

Typical hall of cabinets in the Institute of Geology. Each set of drawers is on a mechanical device for closing the aisles to increase storage space.

This is a row of cabinets with one drawer opened. Note the use of a drawer partially opened underneath for support. (A rough experience once before I learned this trick …)

A typical drawer of specimens. These are newly collected from the Reinu Quarry by our friend and colleague Olev Vinn.

A specimen label. Unfortunately some are nearly indecipherable. Sometimes it is because a Russian worker was transliterating information into Latin letters. There is often an interesting mix between the Russian, Estonian and English languages. Fortunately Ursula and others can quickly translate for us!

We enjoyed working in the Institute of Geology collections very much. They are not only superbly organized, much of their content is listed (and even imaged) online. We saw many critical specimens, and Bill was able to borrow some important crinoids. Thank you to Ursula for her kindness and excellent assistance!

 

The coiled-and-ribbed fossil mystery deepens on Hiiumaa

July 15th, 2012

KÄINA, ESTONIA–It has been a rainy day on the Estonian island of Hiiumaa. The Wooster geologists stayed inside most of the day to work on their Geological Society of America abstracts. Bill Ausich and his Ohio State University team, though, returned to the Hilliste Quarry and continued to collect fossils. To our great surprise, they picked up two more specimens of that strange planispirally-coiled shell that Richa found on July 13. One is shown above, and the “venter” view is shown below. All specimens were found in a yellowish unit that matches the matrix in the fossils (although we’ll check in the lab to make certain). These new finds reduce the chances that the fossils are a product of “site contamination” in which a visitor discards specimens from a previous trip, often to make room for new ones. That is still a possibility, but an increasingly remote one.

So what are these? They look very much like Mesozoic ammonites, all the way down to deflections of ribs along the periphery as you might be able to see above. (Specimen photography in a hotel room has its challenges.) The earliest ammonoids, the larger group that contains ammonites, appear in the Devonian (the period after the Silurian), so it is unlikely we are looking at that group. They are certainly mollusks, though, so most likely gastropods (snails) or nautiloids. Coincidentally enough, Wooster alumnus James St. John has a webpage with a photograph of a coiled, ribbed nautiloid known as Graftonoceras, which you will note has many similarities with our mystery critter. The specimen he photographed is in the museum at, of all places, Ohio State!

Wooster geologists return to Saaremaa and Muhu one last time

July 14th, 2012

KÄINA, ESTONIA–Today the Wooster/OSU team crossed the strait between Hiiumaa and Saaremaa to visit some earlier sites one last time on this trip. The Ohio State paleontologists stayed on the northern part of Saaremaa to look for crinoids and Panga, Ninase and Undva Cliffs; the Wooster geologists went farther south and west to visit Soeginina Pank (above) and Nick Fedorchuk’s 2011 field area. This was important to us so that we could compare observations here to Richa Ekka’s exposure of these beds on the eastern side of the island.

Richa stands by Nick’s Soeginina locality to compare it to her own rocks. This Soeginina section seems considerably more dolomitized in the west than the east.

Jonah and Richa at Nick’s outcrop. Richa is pointing to the Wenlock/Ludlow boundary horizon, and Jonah is showing the stromatolite layer near the top of the section. Richa’s section in the east begins somewhere above her finger.

We were impressed by how poorly preserved the stromatolites are in Nick’s section compared to the gorgeous specimens Richa studied earlier this week. You can barely make out the laminae in this western sample. Look here at its equivalent in the east.

Another difference we noted between the Richa and Nick sections was that Nick’s has thin coral branches (above) in storm layers whereas Richa’s does not. Nick’s oncoids are also larger and more complex.

The amount of damage the Soeginina Pank outcrop received in the last year is astonishing. I had worried about our hammer blows leaving noticeable marks on the rocks. The freshly fallen blocks on the cliff above appeared since our visit last June. Much of this is likely due to ice floes slamming into the rocks during the winter.

After our observations at Soeginina Pank, the Wooster geologists drove to Muhu to visit an historical site (more later on that), then went north through Orissaare to Triigi where we reunited with our OSU companions and boarded the ferry for the ride back to our hotel on Hiiumaa. Our two matching field vehicles are seen above at the front of the ferry. We weren’t going to miss the last ferry to the island!

Quarry work continues on Hiiumaa

July 13th, 2012

KÄINA, ESTONIA–It was a beautiful Baltic day in the Hilliste Quarry on Hiiumaa. Thunderstorms swept by us to the east, but we stayed dry and enjoyed the quickly-changing cloudscape. The Wooster/OSU team was again studying the Hilliste Formation for both its crinoid content and general paleoecology. We did very well.

The typical limestone in the quarry is a biosparite/grainstone as seen above. The most common grains are bits of crinoid stems. The OSU team has found a few crinoid calices and calyx parts, but not as many as you would think given the enormous amount of crinoid skeletal debris in the unit.

It looks like a theme of this year’s Wooster study in the Hilliste Formation may be the sclerobiont (hard substrate-dwelling) fauna, especially the encrusters on corals, stromatoporoids and crinoid stems. Above you see an auloporid coral (the larger tubes connected at their bases) encrusting a favositid coral. Our other encrusters include crinoid holdfasts (three varieties), cornulitids (a kind of worm tube), sheet-like bryozoans, runner-like bryozoans (corynotrypids), and erect bryozoan holdfasts. As far as I know, no one has described a Rhuddanian sclerobiont fauna before.

We have our share of mysteries. Richa picked up the above coiled shell this morning. Bill and I have not seen anything like it in the Silurian before. If these were Jurassic rocks we would have called it a partial ammonite. We know it is not, but we don’t know what it is. A gastropod like Poleumita discors? A nautiloid cephalopod similar to Bickmorites? We’ll have to figure it out later in the lab.

Here is Jonah on the north quarry wall. We dress him brightly every day so we don’t lose him in the Estonian woods.

Richa is in her own world in the western part of the quarry looking for more paleontological treasures.

And finally, our Estonian animal of the day: a spider dutifully guarding her eggs in the quarry floor rubble. I suspect this is the Robust Crab Spider: Xysticus robustus (Hahn, 1832).
 

 

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