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

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.

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Remember those wooden crystal models?

WOOSTER, OH – I’m always awed by the beautiful and perfect symmetry of crystals. I can think of no better way to teach external symmetry than with wooden crystal models. The wooden crystal models are a common experience in geology, across generations and continents, although it seems they may be on the endangered list. I’ve chosen to continue using the models in Mineralogy because they allow students to see and “feel” the symmetry operations and our structural geologist thinks the blocks help students with their spatial reasoning skills.

Behold, the beautiful and mysterious crystal model.

Most people develop a love-hate relationship with the models, but I have to admit I’ve always been infatuated. They’re like logic puzzles with a million different secrets all wrapped up in what seems like a simple wooden block. Spend some time with the block and it will reveal a wealth of information.

This block has 5 mirrors, 1 four-fold rotation axis, and 4 two-fold rotation axes.

This combination of symmetry elements belongs to the point group (or crystal class) 4/m 2/m 2/m. In Hermann-Mauguin notation, 4/m refers to a four-fold rotation axis perpendicular to a mirror. The second and third 2/m terms refer to two-fold rotation axes that are perpendicular to mirrors, one set of axes that exits the crystal in the middle of the faces and another set of axes that exits the crystal on the edges.

The axes (a1, a2, and c) of the tetragonal crystal system align with symmetry elements. Some of the faces have been labeled with their Miller Indices.

The 4/m 2/m 2/m point group belongs to the tetragonal crystal system, which has three mutually perpendicular crystallographic axes. The two horizontal axes (a1 and a2) are equal in length and coincide with the two-fold rotation axes. The vertical axis (c) is longer than the horizontal axes and coincides with the four-fold rotation axis.

Once the crystallographic axes have been determined, we can describe the orientation of the crystal faces using Miller Indices. In short, Miller Indices consist of three numbers (four in the case of hexagonal crystals) that are derived from the intercepts of crystal faces. The crystal face that intersects the a1 axis but parallels the a2 and c axes is assigned a Miller Index of 100. The crystal face that never intersects a1 but cuts both a2 and c is assigned a Miller Index of 011.

We could keep going with this…describing forms, measuring angles, plotting on stereonets, but we won’t. Making it through Miller Indices this week will be enough for the Mineralogy students. Here’s the big secret: this is one of crystals we’re working on in class. I guess we’ll find out which students read the blog on a regular basis!

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Wooster’s Fossils of the Week: Sea urchin bits (Middle Jurassic of southern Israel)

Our fossils this week come from our growing collection of material found in the Matmor Formation (Callovian-Oxfordian) of Makhtesh Gadol, southern Israel. In November I will be giving a talk at the annual meeting of the Geological Society of America in Charlotte, North Carolina, on the taphonomy of Matmor regular echinoids (“sea urchins”). The abstract is online. Taphonomy is the study of the fossilization process. In this case it is essentially what happened to the echinoid remains after death and before final burial. This part of the fossilization history can tell us much about the environment of deposition of the Matmor Formation. The image above is one of the rare complete tests (skeletons) in our study. It is probably a rhabdocidarid echinoid, but the preservation is not quite good enough to tell.

Echinoids are especially interesting for this kind of work. (That link will send you to a wonderful site explaining all you’ll want to know about echinoids and their evolutionary history.) They originated way back in the Ordovician Period, about 450 million years ago, and have retained the same general skeletal structure since then. Their response to physical and chemical conditions on the ocean floor has thus been consistent over time, and we can experiment with modern representatives to estimate their decay and disarticulation processes.

Typical test plate fragments from a rhabdocidarid echinoid in the Matmor Formation. The specimen on the right is encrusted by a very thin plicatulid bivalve, which is in turn encrusted by small branching stomatoporid bryozoans.

A flattened and thorny rhabdocidarid spine. The left end has a socket that attached to a tubercle (bump) on the test of the echinoid.

This cool spine was apparently bitten by a Jurassic fish! Wish I had at least one of that fish’s teeth.

The strange swollen sphere with little holes at the base of this echinoid is a cyst that likely formed from a copepod parasitic infection. Neat (and so far undescribed in the literature).

We can conclude that the Matmor Formation was deposited in very shallow, warm marine waters, probably lagoonal (a favorite living place for rhabdocidarid echinoids), that were only occasionally disturbed by storms and “burial events”. The echinoids decayed and disarticulated on the seafloor (a process that takes about a week) and the pieces tossed around for awhile gathering sclerobionts (encrusters, in this case) and experiencing significant abrasion. This matches other evidence from our previous paleontological studies of the Matmor’s depositional environment.

References:

Donovan, S.K., and Gordon, C.M., 1993, Echinoid taphonomy and the fossil record: Supporting evidence from the Plio-Pleistocene of the Caribbean. Palaios, v. 8, p. 304-306.

Greenstein, B.J., 1991, An integrated study of echinoid taphonomy: Predictions for the fossil record of four echinoid families: Palaios, v. 6, p. 519-540.

Greenstein, B.J., 1992, Taphonomic bias and the evolutionary history of the Family Cidaridae (Echinodermata: Echinoidea): Paleobiology, v. 18, p. 50-79.

Greenstein, B.J., 1993, Is the fossil record of the regular echinoid really so poor? A comparison of Recent and subfossil assemblages: Palaios, v. 8, p. 587-601.

Kidwell, S.M. and Baumiller, T., 1990, Experimental disintegration of regular echinoids: Roles of temperature, oxygen and decay thresholds: Paleobiology, v. 16, p. 247-271.

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Wooster Geologists begin the 2012-2013 school year

WOOSTER, OHIO–Always so much fun to begin a new year with the Wooster Geologists. The happy people above belong to the Geology Club in our annual group photo. This semester we are missing our treasured colleague Shelley Judge who is on a semester research leave. We also have a number of students in off-campus programs.

Here our our senior geologists. Front row from left: Joe Wilch, Richa Ekka, Anna Mudd, Whitney Sims, Kit Price; middle row: Kevin Silver, Jenn Horton, Lauren Vargo, Jonah Novek; back row: Will Cary, Melissa Torma, Matt Peppers.

Today we also posted a colorful pdf of our 2011-2012 Wooster Geology Department Annual Report, the front cover of which is shown above. You can find it at this link with our other recent reports. Thank you very much to cherished Patrice Reeder, our Administrative Coordinator, for her creativity, production skills, and detailed work. It is beautiful.

As you’ve seen in previous posts, we have newly renovated classrooms, and our courses officially began on Monday. The weather is exquisite right now in this part of the country, so we are very much looking forward to our first field trips.

Here’s to happy students and good starts!

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Classes begin again for Wooster Geologists

The happy students above are in our 8:00 a.m. History of Life course (Geology 100). They are the first class to use our newly-renovated Scovel 105 room. To remind you what it used to look like —

This new room is far more comfortable for both students and faculty. We don’t miss the 1985 color scheme either! You can see the progress made on Scovel 105 in this series of images.

Scovel 105 was first officially used for the Junior Independent Study presentation of Kit Price (’13) and the Senior I.S. presentation of Richa Ekka (’13). They each worked during the summer on their projects and gave their summaries to a group of faculty and students on Friday afternoon.

Kit Price (’13) and her very last slide. She worked on Cincinnati area fossils this summer. Note the new lecture table top.

Richa Ekka (’13), also with her last slide. She did field work in Estonia this summer.

 

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Wooster’s Fossils of the Week: an enigmatic set of tubes (Middle Jurassic of Poland)

The fossils this week celebrate the appearance of an article in the latest issue of Palaios authored by an international team led by my good friend and colleague Michał Zatoń (University of Silesia, Poland). The fossils are strange polka-dotted tubes encrusting Middle Jurassic oncoids and concretions from the Polish Jura — a place I enjoyed visiting last summer with Michał. The fossils were quite mysterious to us, but with the help of our new colleague Yasunori Kano (The University of Tokyo), we think we now have a good idea what they represent. Above you see one of the tubes on a concretion.
The polka dots are actually small, regular divots in the sides of the tubes, as shown above in this view through a scanning electron microscope. It turns out that these concavities are the same size as ooids (rounded carbonate grains) in the depositional environment. In fact, occasional ooids are still in their holes, as shown by the white arrow in the image.
In this cross-section through one of the tubes, each of the exterior holes is lined with a thin layer of carbonate, which is apparently the outer layer of an ooid that was cemented into each space. The tube itself is completely occupied by fine carbonate sediment.

Our hypothesis is that the tubes were formed by some sort of polychaete worm similar to serpulids and sabellids (with which they are associated). The worm may have built a hollow living tube by gluing ooids together and possibly taking advantage of the quick-cementing characteristics of this Jurassic calcite sea. It may have then fed on the surrounding microbial mats that covered the concretion and oncoid surfaces. This hypothesis explains the sessile nature of the tubes, their shape and construction, and their association with thin mineralized layers formed by cyanobacteria.

No polychaetes today are known to build living tubes out of ooids, so these Jurassic forms are thus far unique in the fossil and living record. It was a fun paleontological puzzle to tackle with my friends!

We are proud that our little study was chosen as the cover story for the August 2012 issue of Palaios:

“Unusual tubular fossils associated with microbial crusts from the Middle Jurassic of Poland. Upper left, an exposure of Middle Jurassic (Bathonian) clays at Ogrodzieniec in the Polish Jura; lower left, ESEM pictures of morphology and structure of the Middle Jurassic tubular fossils interpreted as remnants of agglutinated polychaete tubes; lower right, two pictures of tubular fossils encrusting oncoid and concretion; upper right, two pictures of recent agglutinated polychaete tubes from Japan.”

References:

Zatoń, M., Kano, Y., Wilson, M.A. and Filipiak, P. 2012. Unusual tubular fossils associated with microbial crusts from the Middle Jurassic of Poland: agglutinated polychaete worm tubes? Palaios 27: 550-559.

Zatoń, M., Kremer, B., Marynowski, L., Wilson, M.A. and Krawczynski, W. 2012. Middle Jurassic (Bathonian) encrusted oncoids from the Polish Jura, southern Poland. Facies 58: 57–77.

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Wooster’s Fossil of the Week: a cameloid footprint (Miocene of California)

This fossil is from near my hometown of Barstow, California. It was collected many years ago loose in talus from the Barstow Formation (Barstovian, Miocene). I note this carefully because today collecting such specimens from the Fossil Beds of the Rainbow Basin Natural Area is illegal, as it should be. This is one of the most fossiliferous Miocene deposits in the world, and it has been heavily vandalized over the years.
The Barstow Formation (in a wonderful syncline) at Rainbow Basin, Mojave Desert, California.

This two-toed footprint is Lamaichnum alfi Sarjeant and Reynolds, 1999. It is preserved as a convex hyporelief, which is essentially a filling of the actual footprint. It was made by a camel-like animal (there are many choices) that walked through stiff volcanic mud along a stream during the Miocene. The impression of this foot was quickly filled with later sediment, probably from an overbank flood.

When I was a kid we found dozens of these footprints in long trackways throughout the Barstow Formation at the Fossil Beds. Those fossils are all gone now, most lost to collectors with rock saws and sledge hammers. Fortunately many have been lovingly preserved in the Raymond M. Alf Museum in Claremont, California. You will note that the ichnospecies of our fossil was named for the charismatic Raymond Alf, a legend in the study of vertebrate trace fossils and a spectacular teacher.

Reference:

Sarjeant, W.A.S. and Reynolds, R.E. 1999. Camelid and horse footprints
from the Miocene of California and Nevada. San Bernardino Museum
Association Quarterly 46: 3-20.

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Upside-down and inside-out: Cryptic skeletobiont communities from the Late Ordovician of Ohio, Indiana, and Kentucky — An abstract submitted to the Geological Society of America for the 2012 annual meeting

Editor’s note: The Wooster Geologists in Indiana this summer wrote an abstract for the Geological Society of America Annual Meeting in Charlotte, North Carolina, this November. The following is from student guest blogger Kit Price in the format required for GSA abstracts:

Upside-down and inside-out: Cryptic skeletobiont communities from the Late Ordovician of Ohio, Indiana, and Kentucky

PRICE, Katherine W. and WILSON, Mark A., Department of Geology, The College of Wooster, 944 College Mall, Wooster, OH 44691

In the majority of the studies in which skeletobiont communities are described, they are found on the exteriors of shell substrates. Skeletobiont communities that inhabited cryptic environments inside some of these same organisms are poorly known. In those instances where cryptic skeletobiont communities have been described, they are on a much larger scale (i.e., cavities in bryozoan reefs and under hardground ledges) and do not include smaller cryptic communities. The Cincinnatian Series of Ohio, Indiana, and Kentucky has many examples of these cryptic communities. Skeletobionts encrusted the interiors of gastropod, monoplacophoran, and nautiloid shells post-mortem, and are mostly made up of sheet and runner-type bryozoans and cornulitids, along with some craniid brachiopods and microconchids. Interestingly, in contrast to other studies on skeletobionts, the majority of the encrusters in our study do not appear to have been concerned with the location of the host aperture. Only the runner-type bryozoans (Cuffeyella and Corynotrypa) appear to have some directional preference, generally increasing their crypticity and branching away from the aperture. However, increasing crypticity is not always the case; sometimes the bryozoans branch parallel to the aperture or even grew towards it. Aside from shedding light on the life habits of these encrusters, these cryptic skeletobionts also inadvertently preserved their hosts through bioimmuration. Bioimmuration is a type of fossil preservation in which a skeletal organism overgrows another, preserving its negative relief. These cryptic communities not only tell us more about the organisms living in these isolated cavities, but they also have preserved detailed external and internal molds of their host aragonitic fauna. This provides information about shell morphology that would have otherwise been lost to dissolution. Because of the abundance of skeletal bioimmuration in the Cincinnatian, a comparison of cryptic to exposed skeletobionts living in the same environments can be made.

____________________________________________________________

The header photograph is of an internal mold of a monoplacophoran mollusk. At the left you can see the branching runners of the bryozoan Cuffeyella, shown in closer view below.

Above is a close-up of the monoplacophoran internal mold. This bryozoan (Cuffeyella) was growing on the inside of the monoplacophoran shell. That shell filled with sediment and then dissolved, leaving the cemented sediment and the underside of the encrusting bryozoan. (Thus the “upside-down and inside-out” preservation.)

This is a view of the underside of skeletobionts that grew inside a nautiloid conch. The conch dissolved, leaving the undersides of various encrusters. A = the inarticulate brachiopod Petrocrania; B = sheet-like bryozoan; C = a rare microconchid with an extended apertural tube; D = another sheet-like bryozoan; E = one of many Trypanites or Palaeosabella borings.

Kit Price (’13) on one of her outcrops in Indiana (C/W-149) on July 28, 2012.

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Wooster’s Fossil of the Week: a bifoliate bryozoan (Upper Ordovician of Indiana, USA)

The specimen above is a species within the trepostome bryozoan genus Peronopora Nicholson, 1881. I don’t know which species because that would require me to slice it open and examine its microscopic skeletal details. (A reason why trepostome bryozoans are not especially popular among fossil collectors!) I found it on a recent field trip to the Whitewater Formation (Upper Ordovician, about 450 million years old) in eastern Indiana for Kit Price’s Independent Study project. Below is a photograph of the outcrop taken by Katherine Marenco (’03) — the most dramatic perspective I’ve seen for that simple roadcut!
Peronopora is bifoliate, meaning that it grew erect and budded on two sides from a central plane. Its skeleton was made of thick calcite, so it was resistant on the Ordovician seafloor during life and after death. As you can see in the close-up image below, the surface of this bryozoan is complex. It had other thin bryozoans growing on it (mainly Cuffeyella), and it was bored by worm-like organisms before and after death.

The genus Peronopora is one of the best studied trepostome bryozoans because of its thick, well preserved skeleton and abundance from the Middle through the Upper Ordovician. (Our specimen is in the Richmondian Stage and so is one of the last of its kind.) Paleontologists listed below in the references have examined in detail the colony growth (astogeny), paleoenvironments, biogeography and stratigraphic occurrences of Peronopora, making it a model for the order. My colleague Tim Palmer and I collected the genus to find beautiful examples of the bioclaustration Catellocaula vallata.

Peronopora was described in 1881 by Henry Alleyne Nicholson (1844-1899), an English paleontologist we’ve seen previously in this blog. The genus has a complicated early taxonomic history, having at one point been considered a kind of sponge.

References:

Anstey, R.L. and Pachut, J.F. 2004. Cladistic and phenetic recognition of species in the Ordovician bryozoan genus Peronopora. Journal of Paleontology 78: 651-674.

Boardman, R.S. and Utgaard, J. 1966. A revision of the Ordovician bryozoan genera Monticulipora, Peronopora, Heterotrypa, and Dekayia. Journal of Paleontology 40: 1082-1108.

Hickey, D.R. 1988. Bryozoan astogeny and evolutionary novelties: Their role in the origin and systematics of the Ordovician monticuliporid trepostome genus Peronopora. Journal of Paleontology 62: 180-203.

Nicholson, H.A. 1881. On the structure and affinities of the genus Monticulipora and its subgenera. William Blackwood and Sons, Edinburgh, 235 p.

Pachut, J.F. and Anstey, R.L. 2009. Inferring evolutionary modes in a fossil lineage (Bryozoa: Peronopora) from the Middle and Late Ordovician. Paleobiology 35: 209-230.

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Grand Canyon Expedition 2012

This summer (26 July through 2 August) I had the pleasure to serve as a guest geologist on a rafting trip to the Grand Canyon. The trip logistics were engineered by Doug Drushal under the auspices of Environmental Experiences, Inc. These trips were begun by former Wooster Geology Professor, Dr. Frederick W. Cropp III in 1980. Doug and Fred’s son Tom Cropp have continued to provide the organization and logistics for these exciting and geologically enlightening rafting trips. Special thanks to JP, our boatman, and Phil (swamper) of Hatch River Expeditions for sharing their knowledge and extensive experience of the history and geology of the Canyon.

The group poses in front of the Great Angular Unconformity. Note the tilted Precambrian Supergroup underlying the Cambrian section consisting of Tapeats Sandstone and Bright Angel Shale (see the stratigraphic section here to remind yourself of the stratigraphy). On the boat is the boatman JP and swamper Phil.

Some of the geological highlights are explained in the captions below. Not only were we treated to classic geology, but we also were able to experience and view some of the power of water in the canyon – flash floods and debris flows.

The reverse exfoliation in the Permian Esplanade Sandstone is one the the best examples of its kind. Usually when we discuss exfoliation we think of domes. The homogeneous nature of the stone along with the local stresses and erosion by the stream combine to give this unnamed side valley of the Grand Canyon such a unique (and highly photographed) look.

Springs emanating from the fractures and karst in the Redwall-Muav Limestone Aquifer provide an oasis in the Canyon and a needed water source for travelers.

Some of the group reclines on chairs in the Throne Room at Dutton Spring in the Redwall Limestone. Clarence Dutton (born in Wallingford, CT) published one of the earliest geologic studies of the canyon in 1882.

An inside-out waterfall (JP’s term). Note the encased waterfall of travertine.  Three physical effects can lead to travertine deposition at waterfall sites: aeration, jet-flow, and low-pressure effects. The three physical effects are induced by two basic changes in the water: an accelerated flow velocity, and enlargement of the air-water interface area. These two changes increase the rate of CO2 outgassing so that a high degree of supersaturation of calcite (travertine) is reached, which then induces travertine precipitation. Note also the four intrepid  explorers who facilitated the older folks into getting more involved with the water holes and falls.

 

 

Robbie reacts strongly to the Great Unconformity (aka Powell Unconformity). This gap in the geologic record is between the lower Vishnu Schist, Precambrian in age and the upper Cambrian Tapeats Sandstone. About 1 billion years is missing at the boundary where Robbie points. Think also about the burial and exhumation stages that must occur to form this, it is quite profound.

Anasazi petroglyphs – this site is dated to AD 1000-1300 and perhaps was abandoned when the Medievel Anasazi droughts descended on the region.

Anasazi ruins – perhaps this outlook spot was occupied by the higher-ups in the society with others practiced dryland farming the floodplain of the Colorado River below.

The group on the overlook point – farther up-valley another settlement is located within sight of this point.

Deer Creek falls – one of the great falls in the Canyon. This stream was rerouted when a landslide dammed the Colorado and displaced the stream. The slide occurred shortly after the damming of the Colorado River by lava flows downstream. This new lake then saturated the Bright Angel Shale, which formed the slip surface of the massive landslide.

The team scopes out lava falls a class ten rapids. Most rapids exist where side canyons bring in large boulders in debris flows that accumulate at the confluence of the tributaries and the Colorado.

A side canyon that experienced a debris flow a few weeks before our trip. In the distance is the Colorado River – it is easy to see how these rapids are evolving as flash flooding and debris flows swept boulders and debris to the river. The tributary was dry the day of our visit.

During our stay in the Canyon there was a massive storm event in the Havasu basin on 1 August. Above is the hydrograph showing the flash flood. We were unable to visit the Havisu Creek the next day because of the high flow. Below one can see the sediment and debris rich water in the Colorado River. Note also on the hydrograph that we had more than one rain event during our days in the Canyon. JP and Phil almost had to evacuate our camp as the Colorado was rising feet per hour.

The flash flood on 1 August flushed out an amazing amount of debris that included more logs and tree debris than seemed to be growing in the canyon. This beach and eddy in the distance is full of wood and debris.

Flying out of the Grand Canyon to Bar Ten Ranch by helicopter. We then took a fixed wing flight out to the Flagstaff Airport.

 

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