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).
 

 

Another new Independent Study project appears: The Hilliste Formation paleoenvironments and paleoecology

July 11th, 2012

KÄINA, ESTONIA–Today Jonah Novek officially began the fieldwork for his Independent Study research: a sedimentological and faunal analysis of the Hilliste Formation (Lower Silurian, Rhuddanian) on Hiiumaa Island, Estonia. Jonah will be continuing the work begun by Rachel Matt (’12) last year in the Hilliste Quarry a few kilometers east of Käina (N 58.87390°, E 022.97198°). He has already today been ably assisted by the generous Ohio State University crew and Richa who gave him numerous fossils they collected from the limestones and shales. Jonah and Richa completed the stratigraphic column today (essentially measurements and descriptions of the rock units, from bottom to top) and began to collect fossils from each unit. We will return at least one more day this week for continued collection.

The Hilliste Formation is very important in evolutionary and ecological studies because it records an Early Silurian “recovery fauna” that lived after the massive end-Ordovician extinctions. There are very few other shelly faunas of this age in the northern hemisphere. This may be the only one that has survived from the ancient paleocontinent of Baltica. The preservation of the fossils is excellent. Above is a heliolitid coral from the unit we have designated “Hi-2″.

Bill Ausich of Ohio State (pictured above in a heroic pose that we call “the Walcott“) found what I think is the most interesting fossil of the day in the Hilliste Quarry. His goal has been to discover as many crinoid calices as possible in the Silurian of the western Estonian islands. Finding such treasures in the Hilliste Quarry started a bit slowly, but he collected this fascinating specimen:

It is a favositid coral surface with two crinoid holdfasts attached. These holdfasts are essentially single roots with little rootlets that gripped the corallites of the coral. There is no more persuasive indicator that crinoids lived with corals here! I had not seen holdfasts like these before, which shows again the value of working with colleagues in the field.

There are also inorganic mysteries in the Hilliste Quarry. Above is an image of a bedding plane near the base of our section (unit Hi-1) that displays ripple marks in a micritic (fine-grained) limestone matrix. The compass shows the north direction, as does the measuring stick. We don’t know how ripples are formed in such a fine sediment (the particles would have been near clay size), nor what environmental forces they indicate. We do know that some show interference patterns (possibly from wave currents) and that they show similar directional orientations.

The only place in the quarry that exposes our lowest unit, by the way, has this wasp’s nest hanging over it. The wasps understandably are quite irritated by hammer blows on the rocks around them, so we must be watchful at this spot!

Good luck to Jonah as he begins his capstone college intellectual adventure. We’ll have more about this project later this week!

 

Wooster/OSU geologists move to another beautiful island with excess vowels: Hiiumaa

July 10th, 2012

KÄINA, ESTONIA–The combined Wooster and Ohio State geology team left Saaremaa Island this morning and traveled to Hiiumaa Island to the north in our search for more Silurian outcrops and their associated fossils. We drove from Kuressaare to Triigi on the northern coast to catch a 9:30 a.m. ferry to Sõru on the southern coast of Hiiumaa. It was my second visit to this island. Like every other place in Europe, it has a long history. Settlement on Hiiumaa goes back to the Fourth Century BCE. For generations the island was known by its German name: Dagö. In recent times it has been Swedish, Russian, German, Estonian, Russian again, German again, and finally part of modern Estonia.

The main attraction for the Wooster Geologists on this trip is Hilliste Quarry (seen above) in the southeastern portion of Hiiumaa. The Lower Silurian (Rhuddanian) Hilliste Formation is exposed here — one of the few in this time interval worldwide. Jonah Novek will be starting his Independent Study project here, building on the labors of Rachel Matt last year. We are all continued to search for crinoids here as part of our joint work.

Jonah is seen here in his first few minutes of examining the Hilliste Formation in our little quarry. The rocks remind me of the Cincinnatian Series because they are a sequence of bioclastic and biomicritic limestones separated by thin beds of shale. This means fossils can be exquisitely preserved on the top and bottom surfaces of the limestones where they meet the soft shales.

An example are these trace fossils preserved on the underside (“sole”) of a biosparite limestone bed. These traces are in “convex hyporelief”, meaning that they stick out on the bottom of the bed. They were formed by deposit-feeding worms of some sort. We’ll have much more on the rocks and fossils of the Hilliste Formation in later posts.

After briefly visiting Hilliste Quarry (mainly a test to see if I really remembered how to get to it), we then traveled to the southeast coast of the island (the Sarve Peninsula) in the hope that we could find some exposures of Silurian limestones. There were tantalizing hints in the limestone shingle along the eastern shore and limestone slabs at the bottom of some roads, but there were many swamps and marshes.

Sometimes we had to use the giant glacial erratics to see above the trees, as Jeff Thompson is heroically demonstrating here.

We never did find additional exposures of bedrock. In the search, though, we saw many gorgeous vistas, like this one of a coastal marsh. (Note the excellent weather, by the way.) We will have several days to continue our quest for limestone on Hiiumaa.

Whenever you wander any distance in Estonia, you find reminders of its bloody and tragic 20th Century history. Rather than repeat the war stories, I’d like to end today with a happier image of a World War II pillbox enlivened by the joyful faces of Jonah and Richa!

 

 

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