New paper on a symbiotic relationship between tube-dwellers and bryozoans in the Silurian of Estonia

I have thoroughly enjoyed my many expeditions to the wondrous Baltic country of Estonia. My Estonian colleagues are fabulous, and I’ve been privileged to share the adventures with numerous students and Bill Ausich of Ohio State. Now during this global pandemic Estonia may as well be on the far side of the Moon. Maybe someday in the New Normal such travel will be possible again.

In the meantime, Olev Vinn has led our small international team to a new paper published today in the journal Lethaia. It is part of a long-term project describing the evolution of symbiosis among marine invertebrates. The abstract follows —

AbstractCornulites sp. and Fistulipora przhidolensis formed a symbiotic association in the Pridoli (latest Silurian) of Saaremaa Island, Estonia. This Cornulites sp.–F. przhidolensis association is the youngest example of cornulitid–bryozoan symbiosis. Symbiosis is indicated by intergrowth of both organisms. The cornulitids are completely embedded within the cystoporate bryozoan colony, leaving only their apertures free on the growth surface of the bryozoan. In terms of food competition, this association could have been slightly harmful to F. przhidolensis as Cornulites sp. may have been a kleptoparasite. There may have been a small escalation in the evolution of the endobiotic life mode of cornulitids as the number of such associations increased from the Ordovician to Silurian. It is likely that Palaeozoic bryozoan symbiosis reached its maximum in the Late Ordovician. Most of the symbiotic bryozoans in the Palaeozoic are trepostomes, and the diversity of symbiotic associations was also greatest among trepostomes.

The image above is Figure 2 from the paper. Caption: Cornulites sp. intergrown with Fistulipora przhidolensis from the lower Pridoli (Kaugatuma Formation) of Lõo cliff, Saaremaa, Estonia (GIT 666‐38). A, detailed view of bryozoan, B, Cornulites sp. [Corn] in cross section, C, D, apertures of Cornulites sp. [Corn] on the growth surface of Fistulipora.

If anyone wants a pdf, just send me an email.

Reference:

Vinn, O., Ernst, A., Wilson, M.A. and Toom, U. 2020. Symbiosis of cornulitids with the cystoporate bryozoan Fistulipora in the Pridoli of Saaremaa, Estonia. Lethaia (https:// doi.org/10.1111/let.12385).

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Let’s celebrate Earth Day!

Happy Earth Day, everyone! Although we can’t all be together this Earth Day, we’re still celebrating wherever we are. We hope you’ll join us in celebrating, too. Check out the video below, which tells you what some of our students and faculty are doing!

 

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New Paper on Antarctic Storm Wave Generation

I was part of a team led by Momme Hell at Scripps Institution for Oceanography that recently published an article in the Journal of Geophysical Research Oceans entitled: “Estimating Southern Ocean Storm Positions With Seismic Observations”. Momme is an expert in detecting seismic waves. We often hear about seismic waves in relation to earthquakes, but on an ice shelf (which is floating on the ocean), the surface also moves up and down with ocean waves.

The reason why Momme brought me on this project was because: 1) storm events are an important generation mechanism for these waves, and 2) I developed an algorithm for detecting and tracking storms from atmospheric data (i.e., atmospheric reanalyses). We wanted to know how well the storms detected from the atmospheric renalsyses aligned with the seismic observations that Momme makes.

The tracks of 2827 storms used in this study. These are on the Pacific-side of Antarctica — including the Ross, Amundsen, and Bellingshausen Seas. Many of the same storms passed by Thwaites and Dotson, Ice Shelves, where Dr. Alley was in Nov 2019 – Jan 2020.

The answer? Not nearly as well as we’d like. Only about 45% of the observations in the reanalyses and seismics align with each other. Some of that error is  from the imperfect relationship between seismic observations and wave-generation by storms, but another reason for error is our imperfect satellite observations of storm systems. The Southern Ocean has some of the sparsest atmospheric observations in the world, and the presence of ample sea ice complicates detection. For example, it’s difficult to distinguish between ice crystals in clouds and the snow/sea ice surface below. In other words, NOAA and NASA and other agencies still have some work to do to perfect the science of weather observation.

An example of how seismic stations on the edge of the Ross Ice Shelf were used to detect the location of maximum wind propagation (orange line and red arrow), and how that compared to the storm track in the reanalysis data (black track with gray point as best match). Winds are typically strongest near but not at the very center of a storm, so this is an example of an ideal match. The dark gray blotch at the bottom is Antartica, and the lighter gray around it is the sea ice. The blue is wave heights (darker blue = bigger waves.)


Here is the plain language summary:
“Surface winds under storms over the Southern Ocean make large ocean waves that travel over long distances (>1,000 km). Regions of wave generation coincide with regions where ocean uptake of heat and CO2 is large, so knowledge about wave generation regions helps us to understand the role of the Southern Ocean in the climate system. A 2‐year field campaign made new observations of ocean wave arrivals at the Ross Ice Shelf. These observations are used to trace the origins of the wave events in the Southern Ocean. Even though the waves observed in the sea ice are much smaller than in the open ocean, the observations are good enough to identify ocean waves. The wave arrivals can be used to infer a most likely time and location of the storm that generated the waves. Comparison with two reanalysis products (Modern‐Era Retrospective Analysis for Research and Applications, Version 2, and ERA5) suggests that more than half of the observed ocean wave events cannot be matched to individual Southern Ocean storms. This high percentage of displaced storms in the reanalysis products can be explained by the limited availability of satellite observations caused by the presence of sea ice.”

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The complex origin of ooids in the Middle Jurassic Carmel Formation of southwestern Utah: Anna Cooke’s Senior Independent Study thesis

Editor’s Note: Independent Study (IS) at The College of Wooster is a three-course series required of every student before graduation. Earth Sciences students typically begin in the second semester of their junior years with project identification, literature review, and a thesis essentially setting out the hypotheses and parameters of the work. Most students do fieldwork or lab work to collect data, and then spend their senior years finishing extensive Senior I.S. theses. This year we have the COVID-19 pandemic to deal with in the spring, so our students have not had a chance to publicly present their hard work and scientific ideas. Some, then, will be writing blog posts like this. The text and images here are from Anna Cooke (’20) who is a member of Team Utah 2019. The picture above shows Anna and fellow team member Evan Shadbolt (’20) on the top of Angel’s Landing in Zion National Park. (Photo by Nick Wiesenberg.) Now Anna takes over —

The Carmel Formation (shown above) formed in a shallow inland sea during the Middle Jurassic and is located in parts of Utah and Arizona. It can be broken into four distinct members, one of which, the Co-op Creek Limestone Member, contains ooid shoals. The ooids in these shoals are calcitic with radial crystals and sparry cement. Several noteworthy features are found in the Carmel ooids, such as delamination, pressure solution, and microborings created by the cyanobacteria: Hyella sp. and/or Solentia sp. Foraminifera are sometimes incorporated into ooids as their nuclei. Seventeen of 21 Carmel thin sections contain foraminiferans inside or outside of ooids. Of these 17, 16 thin sections (94%) show more foraminiferans inside ooids than outside, meaning that ooids can act as taphonomic engineers, preserving what might otherwise not be preserved in the rock record. These foraminiferans likely belong to genera Turrispirulina and/or Ammodiscus. Eolian quartz silt is common in the Carmel shoals. The hypothesis of this study is that a pulse of quartz silt provided nuclei for the formation of the shoals and extinction of the shoals occurred when another pulse smothered it. This is partially supported by point counts, used to determine the percentage of each individual component of these limestones, and nuclei counts, used to determine the percentage of each type of nucleus found in these ooids. The locality that supports this hypothesis most strongly is C/W 142 EMR, which shows three distinct pulses of quartz accompanied by an inverse effect on the percentage of quartz nuclei. Locality C/W 757 DV is also of note, displaying a large amount of quartz early in the shoal’s life, decreasing over time. The percentage of ooids in the shoal shows the inverse. However, other shoals show no such pattern; one method of formation cannot be attributed to all of the Carmel Formation’s shoals, and even those geographically close show marked differences.

Cross-bedded ooid shoal deposit in the Carmel Formation.

Ooids in unit C/W-758A.

I have nothing but positive things to say about my I.S. experience at Wooster. Over the last three semesters, I have had the privilege of researching the Carmel, a formation in southwestern Utah that several other students have done research in. My focus was on ooids: tiny spherical grains composed of calcium carbonate which form in specific marine environments. I have learned so much about these amazing little grains, though at times they made me want to tear my hair out (I personally marked, counted, and recorded the nuclei of over 17,000 ooids)! Though I.S. is a process that comes with a certain amount of stress and frustration, it was also a rich and rewarding experience for me. I learned so much about geology, as well as fieldwork methods and research, writing, and presentation skills. My favorite part of this experience was the field work, which I conducted the spring semester of my junior year with the help of the rest of Team Utah 2019. I am so grateful to everyone who has helped me along in this process, especially my wonderful advisor Dr. Wilson! Independent Study is something I will no doubt remember fondly for the rest of my life!

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Coryphodon and the Paleocene-Eocene Thermal Maximum: Emily Randall’s Senior Independent Study thesis

Editor’s Note: Independent Study (IS) at The College of Wooster is a three-course series required of every student before graduation. Earth Sciences students typically begin in the second semester of their junior years with project identification, literature review, and a thesis essentially setting out the hypotheses and parameters of the work. Most students do fieldwork or labwork to collect data, and then spend their senior years finishing extensive Senior I.S. theses. This year we have the COVID-19 pandemic to deal with in the spring, so our students have not had a chance to publicly present their hard work and scientific ideas. Some, then, will be writing blog posts like this. The text and images below are from Emily Randall (’20) who participated in a Keck Geology Consortium project last summer. The picture above shows Emily on the right in Wyoming (with Isaac and Mike) collecting Coryphodon teeth. And now Emily takes over —

Abstract

Preliminary data point toward a new hypothesis in which Coryphodon lived in wetter habitats before the Paleocene-Eocene Thermal Maximum (PETM), but was able to adapt to drier habitats in order to survive post-PETM. Early Paleogene nonmarine strata are extensively exposed in the Bighorn Basin of northwestern Wyoming. The Fort Union and Willwood Formations represent alluvial deposition within a Laramide Basin formed from the Paleocene through early Eocene. Therefore, the basin is an ideal place to study the local effects of the PETM, a rapid global warming event that occurred about 55.5 million years ago at the Paleocene–Eocene boundary. During this event, an initial decrease in rainfall was followed by wet and dry cycles with increased temperature and decreased precipitation. Some flora and fauna went extinct, but many others exhibited dwarfing during this interval. The response of the large mammal Coryphodon to the PETM is poorly understood, but is of special interest due to its inferred semiaquatic nature.

We collected 14 stratigraphic sections from 5 mammalian biozones within the Bighorn Basin, each centered around depositional units containing Coryphodon. The depositional environments of these units were evaluated by describing the grain size; matrix and mottling colors; mottling percent; abundance and type of nodules; shrink-swell features such as slickensides and clay cutans; and other interesting attributes such as organic matter, invertebrate fossils, sedimentary features, and mottling color or percentage stratigraphic changes. The depositional environments include ponds, swamps, fluvial deposits, soils with evidence of wet and dry cycles, and dry soils.

 

Reflection

Completing my independent study was an extremely rewarding process and I am so happy I was able to have this experience. I was lucky enough to be part of a larger Keck Geology Consortium project, which allowed the team to tackle many more research questions than just one student project ever could. We spent about a month in the Bighorn Basin in northwestern Wyoming collecting data over the summer before I began working on my independent study on campus. It was amazing to be able to gain so much field experience and get to work with such a great team! Back on campus, I was able to focus on data analysis and teaching myself Adobe Illustrator in order to create stratigraphic columns. And then, of course, there was a lot of writing, reading, thinking, and analysis to do to complete my independent study. In the end, I am very proud of how my stratigraphic columns and independent study turned out!

Stratigraphic columns from Clarkforkian (Cf) 2 and 3 mammalian biozones (Pre-PETM).

Some of the Keck Wyoming team collecting Coryphodon fossils. From top to bottom left and then top to bottom right, Michael, Richard, Grant, Simone, Danika, Isaac, and Emily.

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Jurassic bivalves in a shallow epicontinental seaway: Evan Shadbolt’s Senior Independent Study thesis

Editor’s Note: Independent Study (IS) at The College of Wooster is a three-course series required of every student before graduation. Earth Sciences students typically begin in the second semester of their junior years with project identification, literature review, and a thesis essentially setting out the hypotheses and parameters of the work. Most students do fieldwork or labwork to collect data, and then spend their senior years finishing extensive Senior I.S. theses. This year we have the COVID-19 pandemic to deal with in the spring, so our students have not had a chance to publicly present their hard work and scientific ideas. Some, then, will be writing blog posts like this. The text and images below are from Evan Shadbolt (’20) who worked with me on Team Utah 2019. The picture above shows Anna Cooke (’20), Evan Shadbolt (’20) and me at an outcrop of the Carmel Formation (Middle Jurassic) near Gunlock, Utah, in March 2019. And now Evan takes over —

The Jurassic bivalves Plagiostoma ziona (right) and Camptonectes stygius (left).

The Carmel Formation of the Middle Jurassic has many mysteries. One of these enigmas is its bivalves. The formation contains the famous oyster balls called ostreoliths. Despite bivalves making up 80 percent of the fossils found in the Carmel Formation, it is not understood how the bivalves lived in this community. The formation is located in southwestern and central Utah. It was deposited when an epicontinental seaway covered most of Utah. The paleoclimate of Utah was hot and dry, which meant that the environment was evaporite heavy. This also meant that the seawater at the southernmost extent of the seaway in Utah was hypersaline. The bivalves lived in normal marine conditions, but there was little biological diversity. During the Jurassic, there was a calcite sea, and aragonite shells were dissolved away.

In mid-March 2019, I went with a College of Wooster group to southwestern Utah. There we collected bivalves from the Carmel Formation and identified them. Then we researched them and constructed a systematic paleontological overview of the known bivalves. We have possibly identified ten different types of bivalves, and three distinct communities in the Co-op Creek Limestone Member of the Carmel Formation. The communities were the Plagiostoma community, Camptonectes community, and the Liostrea Community. Each of these communities was dominated by a unique bivalve. The Liostrea community was associated with hardgrounds, while the Camptonectes and Plagiostoma communities lived in the same type of environment. We also hypothesize that the area was frequently hit by storms, which caused damage to these communities. The communities were possibly ephemeral, but the bivalves themselves could be considered opportunists. The communities in the Carmel Formation were also small and patchy throughout the area. The bivalve genera that appeared in the Carmel Formation were common in other Jurassic bivalve communities around the world.

My IS experience was fun and unique. Getting to travel to Utah and collect fossils with Team Utah 2019 was a rewarding experience. We spent a week there exploring the Utah environment. Luckily, I was able to collect my fossils over the spring break of my Junior year, so I could start my research early. I felt I was well prepared to start my IS, thanks to the help of the Team Utah 2018 and my advisor, Dr. Wilson. The IS writing experience was not as stressful as I thought it would be. The deadlines were all reasonable and even if I felt I did not do enough work that week, Dr. Wilson was always fine with the amount of work. I feel that the Earth Sciences department at The College of Wooster properly prepare you for writing your IS.

A reconstruction of the bivalve community sampled at Water Tank.

A reconstruction of the bivalve community sampled at Eagle Mountain Ranch.

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Wooster’s Team Utah 2020 Fieldwork

This is the index page for Wooster’s Team Utah 2020 expedition (March 9-13, 2020). The team members above are, from the left, Will Santella (’21), Juda Culp (’21), Nick Wiesenberg (geological technician), and Dr. Shelley Judge (structural geologist and tectonicist). Plus me, of course, Wooster’s sedimentologist and paleontologist. The Pine Valley Mountains are in the background.

This stratigraphic column from the National Park Service details the stratigraphy of southwestern Utah. Our expedition was to continue long-term Wooster explorations of the Carmel Formation (Middle Jurassic) near the top (marked with the red dot). We are preceded by several teams in the 1990s and most recently by Team Utah 2018 and Team Utah 2019. I am a most fortunate professor and geologist to work with such fine people in such a beautiful, stimulating place.

Here are the links to our daily field posts —

March 10: Field geology in a time of plague
March 11: On a Jurassic tidal flat
March 12: Final day in the field (alas)

I hope you enjoy these descriptions and images.

ADDENDUM on March 19, 2020 — Boxes of samples safely arrived in Wooater!

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Wooster’s Team Utah 2020: Final Day in the Field (Alas)

Hurricane, Utah — Last night we made the sad decision to leave for home as soon as possible because of the COVID-19 pandemic. The College has mandated no more in-person teaching, and we don’t want our flight plans to be complicated by cancellations and other mass-transit issues. This is thus our last day in the field.

We started at our treasured oyster-ball locality in Manganese Wash just north of the Gunlock Reservoir (C/W-157; field code MW). This was a key site for Team Utah 2018, but we could not access it last year because the bridge over the Santa Clara River had washed out. The bridge is back so over it we went. This is now Juda’s second site for trace fossils in the upper part of the Co-op Creek Limestone Member of the Carmel Formation. As you can see in the image above with Dr. Judge, there is more brush and weathering at this location than at Eagle Mountain Ranch. This made the trace fossils less crisp in their preservation.

This diffuse set of traces is new to us. It seems to be a deposit-feeding swirl.

Herringbone cross-stratification in this location as well. The paleoenvironment is still shallow and normal marine.

While Juda, Dr. Judge and I worked in the upper Co-op Creek, Will and Nick climbed up a ridge and then down towards the Gunlock Reservoir to visit the lower Co-op Creek and its stromatolites. They again measured, described and collected the unit.

And that was it for our fieldwork! We shipped three heavy boxes of samples back to our Wooster lab. We met our field goals, despite the truncated schedule.

To celebrate, we had another round of Veyo pies and then visited Snow Canyon State Park north of St. George. The Jurassic Navajo Sandstone is weathered in three dimensions here, enabling us to scramble about on its “petrified dunes”. Such a beautiful mix of orange white and black rocks with the green plants and blue skies.

Needless to say, Juda and Will liked the place.

The Jurassic dunes here have deeply eroded foresets at sometimes surprisingly steep angles.

Team Utah 2020! Plus Nick, who took this image. Such a fine crew in skills and enthusiasm.

(Links to the First Day, Second Day, and Third Day.)

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Wooster’s Team Utah 2020: On a Jurassic Tidal Flat

Hurricane, Utah — Our second day was devoted to measuring, describing and sampling Will’s stromatolite-bearing rocks in the lower half of the Co-op Creek Limestone Member of the Carmel Formation. This locality is only a couple of hundred meters west of Juda’s study location yesterday. The rocks are very different: lime mudstones with beautiful markers for their tidal flat origins. We worked in a deep wadi and thus had cliff sections with some bedding plane exposures. Above the team is describing the top of a depositional cycle. (I don’t know why Nick is giving me the side-eye!)

These are bedding-plane exposures of the top of a laterally-linked hemispheroids stromatolite unit.

Just above the previous stromatolites are these desiccation cracks. The tiny pockmarks may be raindrop imprints. The mudcracked units are thick enough in some places to make unusual sedimentary columnar bedding.

These are casts of evaporative gypsum or anhydrite nodules.

An intraclastic limestone grading into a breccia was one of our marker horizons. These rocks are often referred to as “evaporative breccias” because they are associated with the dissolution of evaporite mineral layers and collapse of the mudstones above.

These are delicious columnar stromatolites that made mounds on the sediment surface. The stromatolites are like thick fingers reaching upwards.

This close view shows the packing of the stromatolites. It is almost hexagonal.

An even closer view shows that the stromatolites were burrowed while still relatively soft. Were the trace-makers feeding on the decaying cyanobacterial mats inside? The interstitial sediment in the burrows and between the columns appears to be dolomitized.

Can’t have tidal sediments without herringbone cross-stratification, can we? These structures indicate bidirectional currents, likely from storms or tides.

Lunch in the shade! We had much more sun than yesterday.

Another successful day of field geology. We celebrated at the Veyo pie shop, now a Wooster Utah tradition.

(Links to the First Day, Second Day, and Third Day.)

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Wooster’s Team Utah 2020: Field Geology in a Time of Plague

Hurricane, Utah — This is Team Utah 2020 at Gunlock Reservoir in the far southwestern corner of beautiful Utah. Starting on the left is Juda Culp (’21), Will Santella (’21), Dr. Shelley Judge (our ace structural geologist and tectonicist), and Nick Wiesenberg (our invaluable geological technician). The dipping exposure in the background is the Carmel Formation, a Middle Jurassic (about 170 million-year-old) unit with wonderfully diverse sedimentary rocks and fossils. It is why we are here.

The Carmel has been one of my favorite formations since the early 1990s. I’ve been bringing students and colleagues to study it for many years, the most recent being Team Utah 2019 and Team Utah 2018. This unit has enough variability and mystery for a dozen future teams.

We are again pursuing the Independent Study projects of Wooster students with this field trip. Juda is studying the Carmel trace fossils in a paleoenvironmental context, and Will is examining a series of stromatolites preserved in the lower part of the Carmel.

As you will see, the students were very successful with their fieldwork, but we had to go back to Ohio early because of the COVID-19 pandemic producing travel and health complications. We left Wooster on Monday, March 9, into a risky but predictable world. By Thursday, March 12, it was clear we needed to get back home. We had three days of fieldwork. Juda and Will adapted immediately to the geology and the gorgeous landscapes, so they were disappointed to leave. We accomplished all our measuring and sampling goals, though.

Now the good parts! The images in the following posts were taken by Shelley, Nick and me.

Today we worked on Juda’s project at the productive Eagle Mountain Ranch locality (C/W-142 EMR). Thank you again to the Smith family for giving us access to their land. The thick conglomerate at the top of the section is the Middle Cretaceous Iron Springs Formation. It rests unconformably on the Middle Jurassic Co-op Creek Limestone Member of the Carmel Formation. We spent all our time in the Co-op Creek Limestone Member, which is informally divided into an upper unit (buff-colored; Juda’s rocks) and lower unit (light gray; Will’s rocks). Our prime targets are the loose slabs eroded from meter-thick oolitic limestones. They often have fantastic trace fossils.

Above is a typical slab collected by Juda for its trace fossils. These are burrow-fillings on the bottom of the bed, formally preserved as convex hyporelief.

Every day starts with a field briefing and exchange of initial observations.

Juda hard at work on the steep slope. The skies are cloudy, with temperatures pleasantly in the 50s. Behind Juda’s head are the light-colored rocks Will is studying.

Will collecting trace fossils for Juda. The slabs are weathered just right to show the fossils in crisp relief.

Team Utah 2020 celebrating a successful first field day.

There was just enough time left in the day to visit the St. George Dinosaur Discovery Site.

This museum is always cool, but it was especially relevant today because it is all about trace fossils! We visit every year we’re in town. Dinosaur trackways are the primary subject — most of them in place.

The students were fascinated, especially since they could now consider themselves ichnologists (trace fossil experts).

After our museum visit we had a delicious barbecue dinner and then went back home to our Hurricane lodgings with our samples and observations.

(Links to the First Day, Second Day, and Third Day.)

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