Laboratory microphotography in the Department of Earth Sciences at The College of Wooster (Part 2)

Mark Wilson June 7, 2021 9:25 am

This is the third in a series on laboratory photography in the Department of Earth Sciences at Wooster. In a comment on a Fossil of the Week post last month, Wooster Geologist Alumnus Dr. Bill Reinthal asked if I could describe how we make our blog and other photographic images. I started last week with a post on our macrophotography equipment and techniques. You may want to read that post first for our general photographic processes. Next we had a post on our microphotography using a dissecting microscope with reflected light. This last post is on our microphotography through a petrographic microscope using transmitted light. As I cautioned before, I am not a professional photographer, and my departmental colleagues do plenty of their own excellent photography.

Above is an image of a thin-section cut from an oolitic limestone, the Middle Jurassic Carmel Formation of southwestern Utah. (You may see a theme here! I’ve used the same rocks and fossils in this three-part series to compare the various photographic techniques.) This photograph was taken with the equipment described below. I added the scale later with Adobe Photoshop.

This is our petrographic microphotography station in Dr. Meagen Pollock‘s petrology lab. On the left is a Mac computer running the imaging software from Lumenera (Infinity). Again our wonderful Geological Technician Nick Wiesenberg has written a detailed, easy-to-follow guide to using the system. On the right is the petrographic microscope with a thin-section on the stage.

Another view of the arrangement.

The camera is an Infinity 5 (5.1 Megapixel). It makes fantastic images.

Here again is that Carmel Formation oolitic limestone, this time seen as an acetate peel. Note the differences between the thin-section (top image of this post) and the peel of the same rock. They both show unique details. This is why I like to make both peels and thin-sections of carbonate rocks I’m studying.

Layali Banna (’22) took this microphotograph so we could get some hard-rock, cross-polar action in these blogposts. Feldspars! The scale bar is an example of what the system provides.

Here’s another cross-polar microphotograph from Layali. I don’t know the rock, but it looks like a micaceous sandstone. Thanks, Layali!

These three entries on our laboratory photography systems (macrophotography, microphotography part 1, microphotography part 2) are designed to show our current and future students what we can do in our department. Who knows how long this blog will survive in cyberspace, but maybe someday future Wooster Geologists will arrive here and marvel at our Old Ways!

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Laboratory microphotography in the Department of Earth Sciences at The College of Wooster (Part 1)

Mark Wilson June 6, 2021 12:02 am

In a comment on a Fossil of the Week post last month, Wooster Geologist Alumnus Dr. Bill Reinthal asked if I could describe how we do our lab photography in the Earth Sciences department. I started what will be a three-part series last week with a post on our macrophotography equipment and techniques. You may want to read that post first for our general photographic processes. Today I’m showing our photographic system that uses a dissecting microscope with reflected light. Later we’ll have a post on our microphotography through a petrographic microscope using transmitted light. As I wrote last time, I am not a professional photographer, and my other departmental colleagues do plenty of their own photography. I’m the one who tends to write the most blog posts! (This is entry #1109 for me …)

The above image is of a limestone bedding plane from the Carmel Formation (Middle Jurassic) of southwestern Utah. You can see most of the grains are carbonate ooids, with a scattering of crinoid (Isocrinus nicoleti) debris, including a beautiful star-shaped columnal. (The high-resolution version can be found here.) This image was made with the equipment described below. The scale bar was added later using Adobe Photoshop.

This is our dissecting microscope photographic system. On the left is a fiber-optic gooseneck lamp with two light tubes. The tube on the left is closer to the specimen to produce a dominant light source from the upper left (a paleontological convention to ensure uniform shading). The fiber-optic tube on the right is farther away from the specimen so that it provides a softer fill-in light to brighten the shadowed areas. These are easily moved for various lighting effects depending on the specimen. The microscope in the middle is a Nikon SMZ 1500 with a Lumenera Infinity 3 camera attached in the upper right. The camera taps into the microscope’s light path, so you don’t need to use the eyepieces. The Mac computer on the right is running the Lumenera Infinity photographic software. Our ace geological technician, Nick Weisenberg, has written detailed instructions for using the software with ease.

The Nikon SMZ 1500 microscope has a built-in aperture, which should be closed down as far as possible to get the best depth-of-field.

The camera works very well. We also have versions 4 and 5 attached to petrographic microscopes.

That’s it for this dissecting microscope photographic system! The images it makes are excellent. We spend most of our time composing the scenes and constructing the scale bars. Two more example photographs are below.

This is olivine sand from a Hawaiian beach. (The original is here.)

This photographic system is used often by Dr. Greg Wiles and his tree-ring lab students. It works especially well with sanded tree-ring cores, which are essentially two-dimensional. Layali Banna (’22) made this evocative image last week.

These three entries on our laboratory photography systems (macrophotography, microphotography part 1, microphotography part 2) are designed to show our current and future students what we can do in our department.

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Laboratory macrophotography in the Department of Earth Sciences at The College of Wooster

Mark Wilson June 3, 2021 12:29 pm

In a comment on a Fossil of the Week post last month, Wooster Geologist Alumnus Dr. Bill Reinthal suggested I describe the processes I use to create images of rocks and fossils for this blog, publications and other outlets. This is a good idea because I can produce an outline of our macrophotography techniques for students and others to use as a reference. My only caveat is that I’m not a professional photographer by any means — I’m a scientist who does a lot of photography, trying to retain whatever useful ideas I’ve stumbled across. Like Bill, I’m still building on skills we learned in the Junior Independent Study Geologic Methods course during the last century! I also want to point out that all our departmental faculty and staff do photography and do it well. The following techniques are from my personal perspectives and experiences.

The image above is typical of my lab photography. It is a limestone bedding plane showing trace fossils in convex hyporelief (thus the sole of the bed; the bed is positioned upside-down). This rock is from the Eagle Mountain Ranch exposure of the Middle Jurassic Carmel Formation in southwest Utah, collected during our epic, star-crossed March 2020 expedition. Note the deep black background that provides the ultimate contrast with the edges of the slab. The rock appears to be floating in space with no distractions around it. The dominant light is coming from the upper left, following paleontological tradition for consistency. The yellow scale was added to the image later “in post” as the pros say.

This is the copy stand arranged to take the top image, minus the camera. I believe the four large lights go back at least to the 1970s, and the platform that holds the camera dates to before World War II! The components — A indicates the four main light bulbs (daylight color temperatures); only the back left one is on to produce the required upper-left dominant light source. B is a fiber-optic gooseneck spotlight pair; it is used with smaller specimens so is off. C is a vertical pole that holds the camera mount; the mount can be clamped anywhere along it. D is the camera mount, which has a wingnut-and-spring system to move it vertically in fine increments. (Tighten that wingnut well or the springs can snap the camera up into your face!) E is the copy stand board covered with black velvet to produce the beautiful light-absorbing background. The essential scale cards are always nearby. F is a white piece of cardboard with small light to fill in deep shadows opposite the main lit parts of the specimen. Usually reflection alone is enough fill light, but sometimes I need an extra boost.

Another angle on the copy stand system. You can better see the cantilevered camera mount and the reflective cardboard.

The fancy camera is mounted! This is our latest departmental camera, purchased just last month. It is a Nikon digital single-lens reflex (DSLR) camera, model D5600. The zoom lens attached here is 18-55 mm focal length. I also use a 40 mm lens for really close work. This camera is a dream with its tilting touch screen, superb automatic focus, and multiple shooting controls.

Typically I use the aperture-priority shooting mode, shown by the yellow arrow. This gives me control of the depth-of-field since the shutter speeds can be slow with the sturdy mount. I use “live view”, which allows me to see the composed image on the camera screen. I simply lightly touch the screen where I want the primary focus and the camera takes the picture. Amazing. Occasionally I use exposure adjustments, but most of the time the lighting is good enough as is.

Here is a closer view of the most prominent trace fossil taken with the 18-55 mm lens. By the way, I have no idea what trace fossil this is. Could it be sea anemone burrows? Snail burrows? If you recognize it, let me know!

This image shows as close as I can get with the 40 mm lens, which is closer than any of our previous cameras could do. The rock is an oolite from the same outcrop of the Carmel Formation. Note the crinoid bits scattered amongst the ooids. This is the upper end of the size range for which we do microphotography.

When I’ve finished a photography session I download the images from the memory card into my MacBook Pro computer and do the post-processing with Adobe Photoshop. Most of this work is cropping, with some exposure adjustments and occasional dodging and burning in (terms that only make sense if you remember the days of film and darkroom printing!). The last item I add is the scale bar.

All the image versions on this blog, of course, have been reduced in size for quicker loading on the web. Any images I make that could be useful to others are uploaded in their original dimensions into the Wikipedia system (here is my Wikimedia index page) and designated public domain.

If you have any questions, please ask in the comments, by email or on Facebook! Later I’ll have a similar post on our microphotography systems.

These three entries on our laboratory photography systems (macrophotography, microphotography part 1, microphotography part 2) are designed to show our current and future students what we can do in our department.

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A diatom study begins at Wooster

Mark Wilson June 1, 2021 6:40 pm

This happy Wooster Geologist is Justine Paul Berina (’22). He and I have started a project with diatoms found in mud cores taken from Brown’s Lake and Brown’s Lake Bog by Dr. Greg Wiles, Nick Weisenberg, various crews from the University of Cincinnati, and countless students of Dr. Wiles. Justine and I are honored to join this productive team that has studied this lake and bog system for many years.

Diatoms are microalgae with two-part siliceous skeletons (frustules) found in just about every aquatic system. They manufacture from 20 to 50% of our atmospheric oxygen and cycle billions of tons of silica through the environment. If you want more details on diatoms, check out what I consider the best website ever devoted to a taxonomic group: Diatoms.org.

Diatoms are especially helpful for assessing the health of water systems because they are very sensitive to aquatic geochemistry and ecological changes. This is how Justine and I are using the Brown’s Lake diatom distributions, essentially as paleoecological tools.

Above is Brown’s Lake Bog, familiar to generations of Wooster students and readers of this blog.

Justine devoted his Junior Independent Study project last semester to examining diatoms from a Brown’s Lake Bog core. He used an existing collection of smear slides to first find where diatoms were most common, and then he made his own slides. Justine and I are very fortunate to have the advice of a diatom expert, Dr. Julie Wolin at Cleveland State University. Dr. Wolin corrected our diatom identifications and has given us many ideas for future work.

Our project involves studying the diatoms in core sections before and after agricultural work began in the Brown’s Lake area. We want to see how the lake and bog conditions changed with the anthropogenic modifications of the drainage systems and soils.

This is an image Justine made of our most common Brown’s Lake Bog diatom, Pinnularia.The diatom Stauroneis has a subtle “bowtie” in its center.

There are also numerous siliceous sponge spicules scattered through the cores. We hope they have some paleoecological value as well.

Justine has only a few more days left in the lab before he travels to the University of Delaware for a summer internship. I will continue our work on diatoms until Justine returns in August to begin his Senior Independent Study project on the critters.

Again Justine and I are proud to join the Brown’s Lake crew and look forward to making our contributions to the science!

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Wooster’s Fossils of the Week: Giant Pliocene scallop from Virginia with bonus sclerobionts

Mark Wilson May 30, 2021 3:31 pm

Yes, the feature “Wooster’s Fossil of the Week” was retired long ago (all entries still available on this blog), but occasionally I will still cover interesting fossils we come across in the lab or field. The title is now a tradition, even if the items don’t appear every week. No good fossils should be left behind.

The beautiful specimen above was kindly donated to the department last week by Wooster Geologist Alan Troup (’96). He found it and several other specimens in the Yorktown Formation (the Pliocene part) along the York River in Virginia. It will be used in our Paleoecology course next year. These fossil scallops are incredibly abundant, and this is an especially nice one with its numerous sclerobionts (hard-substrate-dwelling organisms). The main shell is Chesapecten jeffersonius, one of the largest scallops ever and the state fossil of the Commonwealth of Virginia. (I don’t know if “Commonwealth Fossil” is a thing.) It is encrusted on the outside only by large barnacles. Near the hinge are numerous perforations from clionaid sponges, making the trace fossil Entobia. It makes for a sweet little community.

Here’s a closer view of Entobia. Each hole leads to a tunnel system in the thick scallop shell.

Other scallops in the collection are encrusted by these thin scleractinian corals with radiating septa inside the  corallites.

The arrow points to a predator drill hole (the trace fossil Oichnus) through the scallop shell. It was made by a naticid gastropod.

Alan’s donation also includes oysters like the above. I’m sure you by now see the included trace fossils!

One of the many interesting questions about these sclerobiont-laden scallops is whether they could do their “swimming” while so heavily encrusted on their exteriors. As you can see in this video, modern scallops can swim today with a good load of passengers.

Reference:

Ward, L.W. and Blackwelder, B.W. 1975. Chesapecten, a new genus of Pectinidae (Mollusca: Bivalvia) from the Miocene and Pliocene of eastern North America. U.S. Geological Survey Professional Paper 861, 24 p.

 

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Milestones for two Wooster Geologists

Mark Wilson May 26, 2021 5:43 pm

There was some good news for the College of Wooster Earth Sciences faculty during the otherwise dreary Pandemic Year. The two cheerful Wooster geologists pictured above in the field (today!) reached important points in their professional lives.

Dr. Meagen Pollock was promoted to Full Professor this spring. This is a big deal in the academic world. The criteria are: “The College expects that faculty portfolios for promotion to Professor will demonstrate significant and sustained achievements in the areas of teaching, scholarship, research, and general value to the College after those that led to tenure and/or the rank of Associate Professor.” She’s going to have to update that faculty webpage!

This year Dr. Greg Wiles was elected a Fellow of the Geological Society of America. The requirements: “Society Fellowship is an honor bestowed on the best of our profession by election at the spring GSA Council meeting. GSA members are nominated by existing GSA Fellows in recognition of a sustained record of distinguished contributions to the geosciences and the Geological Society of America through such avenues as publications, applied research, teaching, administration of geological programs, contributing to the public awareness of geology, leadership of professional organizations, and taking on editorial, bibliographic, and library responsibilities.” Greg’s nomination was in two categories: “Publication of the results of geological research” and “Training of geologists”. No more than two categories could be selected — otherwise he would have more!

Congratulations to Meagen and Greg. They are heroes!

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Wooster Memorial Park – Now Part of the Old Growth Forest Network

gwiles April 26, 2021 12:45 pm

On 20 April 2021 Wooster Memorial Park became part of the Old Growth Forest Network.  The founder and director, Joan Maloof, visited Wooster Memorial Park forest to officially induct the park into the Network. The Wooster Tree Ring Lab cored some of the white oaks in the park to determine their age and to see how they are responding to the increasingly wetter climate of Northeast Ohio. Nathan Kreuter (Biology) and Nick Wiesenberg (Earth Sciences Dept. Technician) found the oldest trees and helped work up the tree-ring data.

Joan Maloof with the largest hemlock in the park.

Nathan Kreuter cores one of the oldest oaks as part of his tutorial at the Wooster Tree Ring Lab.

The ring-widths of the Wooster Memorial Park chronology. There was a likely time of early logging in the park about 1815 and again in the 1920s
Tree ring widths are most sensitive to April-August total precipitation. The correlation between the ring-widths and precipitation changes over time with the strongest relationship r = 0.6 for the interval 1945-1975. After 1975 the correlation falls off possibly due to the increase in precipitation and loss of sensitivity at the site with the abundant moisture.

Friends of the trees and Friends of Wooster Memorial Park with Joan Maloof.

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Microbial Structures of the Middle Jurassic (Bajocian) Carmel Formation, Southwest Utah: William Santella’s Senior Independent Study thesis

Mark Wilson April 16, 2021 6:14 pm

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 again had the COVID-19 pandemic to deal with, so our students have had few chances 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 Will Santella (’21), who is a member of Team Utah 2020. The picture above shows an outcrop of the Lower Co-op Creek Limestone Member of the Carmel Formation at the Gunlock Reservoir, Gunlock, Utah. Now Will takes over —

The Lower Co-op Creek Limestone Member of the Carmel Formation (pictured above) is a sedimentary unit that formed at the southernmost tip of the epicontinental Sundance Seaway during the Bajocian stage of the Jurassic period. This thesis regards a small portion of the Lower Co-op Creek Limestone Member, located near the town of Gunlock, Utah. Among the plethora of invertebrate fossils lying in this unit are microbialites; ancient fossilized photosynthetic cyanobacterial mats which grew in the shallow-marine tidal zones characteristic of the Lower Co-op Creek Limestone Member.

These “microbialites” are classified in two groups; the laminated “stromatolite”, and the clotted “thrombolite”. The purpose of my thesis was to describe these extraordinary lifeforms by analyzing patterns in stromatolite laminae, and identifying unique thrombolite morphology.

Laterally-linked hemispheroid stromatolites at the Gunlock Reservoir locality.

Stromatolites are laminated benthic microbial deposits first identified by Ernst Kalkowsky in 1908. Formed by the lithification of sediment by photosynthetic cyanobacteria, stromatolites exhibit a variety of morphologies; those in the Carmel Formation are composed of finely layered continuous laminae. In an ideal environment, a stromatolite lamina is a perfect record of the sedimentary, biological, and atmospheric conditions at the time of lamination. I applied principals of cyclical harmonic analysis to laminae data in an attempt to map chronological changes in the morphology, composition, and habit of stromatolite laminae in the Lower Co-op Creek Limestone Member. This analysis was conducted by using a harmonic wavelength generator in RStudio to create models of cyclical changes in the recorded attributes of stromatolite laminae; the results of which were remarkable.


Laterally-linked hemispheroid stromatolite laminae under a petrographic microscope.

Chart describing trends in stromatolite lamination via a harmonic model (blue) and a linear regression model (red).

While I determined that there was no statistically significant change in stromatolite laminae over time, the morphology, composition, and habit of a stromatolite lamina was the direct result of the tidal stage under which it formed. “High tide laminae” were thicker, exhibited large diagenetic dolomite crystals, and contained a greater abundance of large quartz grains than their related “low tide laminae”, which were thin, and primarily composed of micritic sediment. This previously undescribed relationship between tidal stage and stromatolite lamination is key to understanding the growth patterns of these phenomenal organisms.

Thrombolite hand sample displaying unique clotted morphology.

Thrombolites are defined as cryptalgal structures related to stromatolites but lacking lamination and characterized by a macroscopic clotted fabric (Aitken, 1967). The term “macroscopic clotted fabric” refers to the matrix of internal mesoscopic structures that are composed of individual, distinct microbial colonies. These mesoscopic structures can be anywhere from less than a millimeter to several centimeters wide, and are separated by a dividing matrix of sediment, biological debris, or sparry carbonate (Kennard and James, 1986).

The thrombolites of the Lower Co-op Creek Limestone Member are unique- specifically, the small, lightly clotted morphology of these organisms is not described in literature regarding Bajocian paleontology. Additionally, thrombolite structures from the Carmel Formation do not match any of the widely used thrombolite morphology classifications described by Theisen and Sumner (2016). These thrombolites exhibit a light clotted fabric divided by dark, fine grained sediments, and do not display layered microbial matrix features within clots, as is characteristic of many thrombolite classifications.

I ultimately determined that while the thrombolites of the Lower Co-op Creek Limestone Member were morphologically unique, their formational environment was consistent with the shallow marine, slightly turbulent thrombolite reef facies similar to that of their predecessors.

There are many aspects of the Independent Study process which I enjoyed- field work amidst the stunning Utah desert, 50-hour weeks in the quiet isolation of our Scovel Hall paleontology lab, and rigorous scientific study. Beyond all of that, I spent my days working with the fossilized remains of organisms I have been fascinated with for years- holding a deep and almost spiritual respect for the lifeforms that many regard as evidence of the first life on Earth. I owe a great deal of thanks to the Earth Science Department- especially Patrice Reeder for her part in organizing Team Utah 2020, and Dr. Judge for sparking my interest in stromatolites, mentoring me through my degree, and providing superior camaraderie. I thank my superlative advisor, Dr. Wilson, for aiding me over my years at the college both as a professor and as a friend, and for making my passion project a reality.

References:

Aitken, J.D., 1967, Classification and environmental significance of cryptalgal limestones and dolomites, with illustrations from the Cambrian and Ordovician of southwestern Alberta: Journal of Sedimentary Petrology, v. 37, p. 1163-1178.

Kalkowsky, E., 1908, Oolith und stromatolith im norddeutschen Buntsandstein: Zeitschrift der Deutschen Geologischen Gesellschaft, v. 60, p. 68-125.

Kennard, J.M., and James, N.P., 1986, Thrombolites and stromatolites: two distinct types of microbial structures: Palaios, v. 1, p. 492-503.

Theisen, C.H., and Sumner, D.Y., 2016, Thrombolite fabrics and origins: Influences of diverse microbial and metazoan processes on Cambrian thrombolite variability in the Great Basin, California and Nevada: Sedimentology, v. 63, p. 2217-2252.

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Wooster Geologists featured in The Chronicle of Higher Education

Mark Wilson April 9, 2021 10:18 am

The Senior Independent Study process for Morgan Pedroso Curry (’21) and his creative, enthusiastic advisor Dr. Shelley Judge is the subject of an excellent article in The Chronicle of Higher Education this week. (The article may be behind a pay wall for some readers. If you want a pdf copy, we can arrange it.) The images in the article, including the one above, were taken by Wooster’s ace photographer Matt Dilyard. The October 2020 COVID-restricted fieldwork for Morgan’s IS project was recorded in this blog entry by Dr. Greg Wiles.

Well done, Team Morgan!

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A new “living fossil” bryozoan with a Wooster connection

Mark Wilson March 13, 2021 11:43 am

Way back in the summer of 2008, my good friend Paul Taylor (the Natural History Museum, London), John Sime (Senior Independent Study student at the time) and I explored the Pierre Shale (Upper Cretaceous) of the Black Hills region in South Dakota, Wyoming and Montana. We collected numerous conchs and internal molds (steinkerns) of the abundant ammonite Baculites. Some of the internal molds had beautiful networks of connected tear-drops molded in the sediment that had filled the empty shells on the Cretaceous seafloor (image above). These represent skinny bryozoan colonies that lived attached to the inside walls of the shells. These bryozoans were soft-bodied with no hard parts and so were preserved as molds within molds, a kind of taphonomic complexity we always enjoy.

In 2012, Paul and I published a description of these bryozoans, describing them as a new genus and species of ctenostome bryozoan: Pierrella larsoni (see Wilson and Taylor, 2012, and this Wooster Fossil of the Week entry). Above are photographs of ammonite steinkerns showing the undersides P. larsoni (figure 28.1 of Wilson and Taylor, 2012). The specimen above on the left is from Red Bird, Wyoming, and the one on the right is from the Heart Tail Ranch in South Dakota. The scale bars are 10 and 5 mm respectively.

One of the most interesting feature of Pierrella is a remarkable “pleated collar” at the zooid aperture. In the image above, we’re looking at a mold of the collar, which was, like everything else in this bryozoan, soft tissue. From Figure 28.4 of Wilson and Taylor (2012); scale bar = 50 µm.

Now the cool “living fossil” part. Several years later, Russian scientists examined metalliferous seafloor nodules in the deep-sea Clarion-Clipperton Fracture Zone of the eastern Pacific Ocean. This area is receiving considerable attention for deep-sea mining, so teams of ecologists and biologists are surveying the biodiversity in this zone to assess the damage that could be done to this dark ecosystem around 5000 meters deep. Turns out there is a considerable bryozoan fauna down there.

And guess who is a part of this deep-sea community? Pierrella! In 2018, Grischenko et al. published a paper describing Pierrella plicata, a modern species of a genus described  from the Late Cretaceous. Just last week, Schwaha et al. (2021) described the anatomy of this taxon. Above images are from their figure 2: (b) colonies attached to the surface of an arenaceous foraminiferan, showing dispersed zooids and thin proximal cystid appendage; (c) a single zooid; (d) the apertural folds — our Pierrella pleated collar! (Abbreviations: ap – aperture, pca/cd – proximal cystid appendage/cd, z – zooid.)

So our little Cretaceous Pierrella was recognized in the Modern by its fancy apertural collar, which was preserved in an unusual way we still don’t fully understand. The wonders of paleontology.

The modern Pierrella is an example of a “living fossil“, meaning that it very closely resembles an ancient fossil form. Paleontologists are not thrilled with this category, so I keep it in quotation marks. A popular misconception is that a “living fossil” has “not evolved” during some extended interval (about 75 million years in our case here). However, evolution proceeds along all sorts of pathways that are not always possible to see with a fossil-to-living comparison. Internal organs may have changed dramatically and we wouldn’t know. There is also the possibility of evolutionary convergence. Certainly the environmental differences are extraordinary for Pierrella: the Cretaceous version was found in shell interiors in relatively shallow waters whereas the modern form is about 5000 meters deep. Still, the similarities between fossil and modern Pierrella are intriguing.

You know who really likes “living fossils”? Creationists! They have the mistaken belief that these organisms show that no evolution took place between fossil and modern taxa. The fossil to them is just an example of the modern a few thousand years older. Check out the “living fossil” pages for Answers in Genesis and the Institute for Creation Research. I would love to see them add Pierrella to their benighted lists so I could call them out on it.

 

References:

Grischenko, A.V., Gordon, D.P., and Melnik, V.P. 2018. Bryozoa (Cyclostomata and Ctenostomata) from polymetallic nodules in the Russian exploration area, Clarion-Clipperton Fracture Zone, eastern Pacific Ocean-taxon novelty and implications of mining. Zootaxa, 4484(1), 1-91.

Schwaha, T., Grischenko, A.V., and Melnik, V.P. 2021. Morphology of ctenostome bryozoans: 4. Pierrella plicata. Journal of Morphology. doi: 10.1002/jmor.21344

Wilson, M.A. and Taylor, P.D. 2012. Palaeoecology, preservation and taxonomy of encrusting ctenostome bryozoans inhabiting ammonite body chambers in the Late Cretaceous Pierre Shale of Wyoming and South Dakota, USA. In: Ernst, A., Schäfer, P. and Scholz, J. (eds.) Bryozoan Studies 2010; Lecture Notes in Earth Sciences 143: 399-412.

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