Wooster’s Fossils of the Week: “Ghosts” in the Upper Ordovician of Kentucky

October 13th, 2017

This year Caroline Buttler (Department of Natural Sciences, Amgueddfa Cymru – National Museum Wales) and I had a great project describing a cave-dwelling fauna in the Upper Ordovician of northern Kentucky. We hope that work will appear soon in the Journal of Paleontology. During our lab studies of thin-sections and acetate peels of massive trepostome bryozoans, we found several examples of clear calcite bodies in the middle of sediment-filled borings. These structures were described from the Ordovician of Estonia as “ghosts” of soft-bodied organisms by Wyse Jackson and Key (2007). They appear to be mineralized casts of organisms that were buried when sediment filled the borings that they occupied.

Meanwhile, Luke Kosowatz (’17) has a senior Independent Study project assessing bioerosion in the Upper Ordovician of the Cincinnati area. He and I have also found numerous examples of these ghosts in borings, so many that they have become a phenomenon in themselves for study. Above is an acetate peel made tangentially to the bryozoan surface showing the numerous tubular zooecia punctured by a few larger borings. Most of these borings are filled with sediment, but the two indicated by the arrows have these calcitic ghosts. This specimen is from the Corryville Formation near Washington, Mason County, Kentucky (38.609352°N latitude, 83.810973°W longitude; College of Wooster location C/W-10).

Above is one of our many heavily-bored trepostome bryozoans. This one comes from the Bellevue Formation (Katian) exposed on Bullitsville Road near the infamous Creation Museum (C/W-152). The irregular holes are the cylindrical boring Trypanites. The ghosts are not visible without sectioning.

Here is a close view of one of the ghostly calcitic casts in an acetate peel. The boundaries are sharp between the ghosts and the surrounding sediment.

The arrows above show ghosts in longitudinal cross-sections. Note their extended oval shapes. These are clearly organic shapes under these circumstances. (This is a thin-section.)

So what do the ghosts represent? They could be remains of the boring organisms themselves. If they are, they can be used to address a problem we have with bioerosion: What is the temporal relationship between the borings? How many were active in a given substrate at a given time? The percentage of borings with ghosts may give us a minimum amount of contemporary bioerosion. If, again, these are remnants of the borers themselves.

Maybe the ghosts are of later organisms that occupied the borings after the borers died? This happens often, with the secondary inhabitants called nestlers.

I know of no way to sort possible borers from nestlers with this kind of evidence.

The above image shows it’s possible that some of the ghosts are of organisms that had shells. The arrow is pointing to a dark line that may represent the remains of some type of shell. I’ve seen little tiny lingulid brachiopods in some borings before.

A fun mystery!

For technical interest, here is our photomicroscope we use to produce images like those in this post.

References:

Cuffey, R.J. 1998. The Maysville bryozoan reef mounds in the Grant Lake Limestone (Upper Ordovician) of north-central Kentucky, in Davis, A., and Cuffey, R. J., eds., Sampling the layer cake that isn’t: the stratigraphy and paleontology of the type-Cincinnatian. Ohio Department of Natural Resources Guidebook 13: 38-44.

Wyse Jackson, P.N. and Key, M.M. Jr. 2007. Borings in trepostome bryozoans from the Ordovician of Estonia: two ichnogenera produced by a single maker, a case of host morphology control. Lethaia 40: 237-252.

 

A “Dry Summer” in Wooster?

October 12th, 2017

I moved to Wooster at the very end of July.  Since that time, I’ve heard a frequent refrain that “it’s been a dry summer”.  Being a climate scientist, and knowing that everyone (including me) likes to complain about the weather, I thought I’d fact-check my neighbors.  In meteorology, “summer” usually means June, July, and August (JJA).  Based on data from the Wooster Experimental Station, 11.12 inches of rain fell during JJA 2017.  Is that dry?

It turns out, that’s nearly average.  The Wooster weather station goes back to the 1800s, and for the period 1900-2016*, the average JJA precipitation was 11.52 inches.  The minimum is 4.34 inches (1910), and the maximum is a 23.72 inches (1935).  However, my neighbors may be on to something, because digging deeper, most of that rain fell in June and July.  Early summer was really wet actually — the 9.83 inches Wooster received in June and July was greater than 75% of all years since 1900.  In August, though, we only received 1.29 inches — well below average.

September was even drier at 1.13 inches.  The main storm track that brings rain to Wooster has been farther north than normal since July, and most storms have missed us.  We also often receive rain from the remnants of hurricanes in September.  Although September had plenty of Atlantic hurricanes, Harvey is the only one that affected Wooster, dropping 0.76 inches of rain.  That’s a pittance for a tropical system, but it was also over half the rain we saw all month.

If you combine August and September, we had 2.42 inches of rain.  That’s good for 4th lowest since since 1900 (Figure 1).  Also, it’s the lowest August-September precipitation since 1922 — almost 100 years ago.  So yeah, this is rare.

Figure 1. In 2017, Wooster received 2.42 inches of precipitation in August and September. That’s 4th lowest since 1900. Data from National Centers for Environmental Prediction.

In fact, it’s so rare that Wooster is currently in a moderate drought (Figure 2). Cincinnati, Louisville, and other cities farther south are fine — they received ample rain from the tropics this year.  Much of the midwest is dry, though.  With that said, these midwest droughts are nowhere near as bad as the recent one in California (which still lingers in southern California, by the way). They are not as bad as what Montana and the Dakotas are currently facing, either.  Besides the moderate severity, they’re also currently short-term droughts — meaning it’s only been around for a few months.  Such droughts may have adverse impacts on agriculture, but there’s typically no long-term impact.  Just hope for plenty of snow this winter!

Figure 2. Droughts in the USA as of 3 October 2017. Wooster, OH is in a short-term moderate drought. Data from drought.gov.

 

*There are some data gaps before 1900 in the NCEI data, so I skipped those years.

Wooster’s Fossil of the Week: A terebratulid brachiopod from the Upper Cretaceous of southwestern France

October 6th, 2017

Yes, we’ve had a run of French Cretaceous fossils here. This is because we’re in the midst of a major project stemming from summer fieldwork in the Type Campanian of southwestern France. The fossils are delicious, and they are before us every day in the lab.

The above terebratulid brachiopod was found by Macy Conrad (’18) at our Caillaud South locality in the Biron Formation. It is so beautifully symmetrical that it just had to be a Fossil of the Week. I’ve apparently felt this way before about terebratulid brachiopods since I’ve previously written about Triassic, Jurassic and Miocene examples before in this blog. A Cretaceous example at least completes the Mesozoic set.

The above view of our articulated specimen shows the fragmentary smooth dorsal valve of the terebratulid, with the posterior portion of the ventral valve extending upwards at the top. The ventral valve has the characteristic round pedicle opening.

This is the flip side showing only the exterior of the ventral valve. A bit of chalky matrix adheres in the lower left, and the darker circles at the top are a form of silicification called beekite rings.

Here is the side view of our terebratulid, with the dorsal valve on top and larger ventral valve below. You can see why brachiopods were given the common name “lamp shells” because of the resemble to a Roman oil lamp.

References:

Coquand, H. 1858. Description physique, géologique, paléontologique et minéralogique du département de la Charente. Besançon, Dodivers, 420 p.

Platel, J.-P. 1996. Stratigraphie, sédimentologie et évolution géodynamique de la plate-forme carbonatée du Crétacé supérieur du nord du basin d’Aquitaine. Géologie de la France 4: 33-58.

Wooster’s Fossils of the Week: An oyster reef from the Middle Jurassic of southwestern Utah

September 29th, 2017

It was a pleasure to pull this massive specimen out of the cabinets, where it had been sitting for more than 20 years. It is a small reef of the oyster Liostrea strigilecula (White, 1877) from the Carmel Formation (Middle Jurassic) near Gunlock, southwestern Utah. It is out of storage because I’m returning to this section in Utah with students this summer to begin fieldwork again. The rocks and fossils are fascinating, and it is time someone looked seriously at them again.

A closer look at these little oysters shows how they could construct such a tight, nearly seamless structure. Each oyster grew in a cup-like fashion (first pointed out by Tim Palmer) so that they nestled together rather than overgrowing each other. These same oysters in this same locality also formed the famous oyster balls (ostreoliths). These reefal equivalents grew on carbonate hardgrounds, which are abundant in the Carmel Formation.

Liostrea strigilecula was named by Charles Abiathar White (1826-1910) as Ostrea strigilecula in 1877. White was an American paleontologist and geologist who did considerable work on midwestern and western North America. He was born in Massachusetts and worked in Iowa as the state geologist from 1866 to 1870. He returned east to teach at Bowdoin College for a couple of years, and then he joined the United States Geological Survey from 1874 into 1892. In 1895 he became an associate in paleontology at the United States National Museum. White was one of the first fellows of the American Association for the Advancement of Science, one of the first members of the Geological Society of America, and he was elected a member of the National Academy of Sciences in 1889. Abiathar Peak in Yellowstone National Park was named after him. A more thorough biography can be found at the link.

I’m looking forward to seeing these beautiful oysters in the field again!

References:

Bennett, K. 2017. White, Charles Abiathar. The Biographical Dictionary of Iowa. University of Iowa Press, 2009. Web. 19 September 2017

Nielson, D.R. 1990. Stratigraphy and sedimentology of the Middle Jurassic Carmel Formation in the Gunlock area, Washington County, Utah. Brigham Young University Geology Studies 36: 153-192.

Taylor, P.D. and Wilson, M.A. 1999. Middle Jurassic bryozoans from the Carmel Formation of southwestern Utah. Journal of Paleontology 73: 816–830.

Wilson, M.A. 1998. Succession in a Jurassic marine cavity community and the evolution of cryptic marine faunas. Geology 26: 379–381.

Wilson, M.A. 1997. Trace fossils, hardgrounds and ostreoliths in the Carmel Formation (Middle Jurassic) of southwestern Utah, in Link, P. and Kowallis, B., eds., Mesozoic to recent geology of Utah, Brigham Young University, v. 42, p. 6–9.

Wilson, M.A., Ozanne, C.R. and Palmer, T.J. 1998. Origin and paleoecology of free-rolling oyster accumulations (ostreoliths) in the Middle Jurassic of southwestern Utah, USA. Palaios 13: 70–78.

Wooster’s Fossils of the Week: Chaetetids from the Upper Carboniferous of Liaoning Province, North China

September 22nd, 2017

1 Benxi chaetetid 2a 585Three years ago I had a short and painful trip to China to meet my new colleague and friend Yongli Zhang (Department of Geology, Northeastern University, Shenyang). The China part was great; the pain was from an unfortunately-timed kidney stone I brought with me. Nevertheless, I got to meet my new colleagues and we continued on a project involving hard substrates in the Upper Carboniferous of north China. Above is one of our most important fossils, a chaetetid demosponge from the Benxi Formation (Moscovian) exposed in the Benxi area of eastern Liaoning Province. We are looking at a polished cross-section through a limestone showing the tubular, encrusting chaetetids. This month the paper on these fossils has at last appeared.
2 Chaetetid Benxi Formation (Moscovian) Benxi Liaoning China 585This closer view shows two chaetetids. The bottom specimen grew first, was covered by calcareous sediment, and then the system was cemented on the seafloor. After a bit of erosion (marked by the gray surface cutting across the image two-thirds of the way up), another chaetetid grew across what was then a hardground that partially truncated the first chaetetid. This little scenario was repeated numerous times in this limestone, producing a kind of bindstone with the chaetetids as a common framework builder.
3 Chaetetid Benxi cross-section 585Here is the closest view of the chaetetids, showing the tubules running vertically, each with a series of small diaphragms as horizontal floors.

Last week’s fossil was a chaetetid, introducing the group. They are hyper-calcified demosponges, and the classification of the fossil forms is still not clear. Their value for paleoecological studies, though, is clear. This particular chaetetid from the Benxi Formation preferred a shallow, warm, carbonate environment, and it was part of a diverse community of corals, fusulinids, foraminiferans, brachiopods, crinoids, bryozoans, gastropods, and algae. Such hard substrate communities are not well known in the Carboniferous, and this is one of the best.

References:

Gong, E.P, Zhang, Y.L., Guan, C.Q. and Chen, X.H. 2012. The Carboniferous reefs in China. Journal of Palaeogeography 1: 27-42.

West, R.R. 2011a. Part E, Revised, Volume 4, Chapter 2A: Introduction to the fossil hypercalcified chaetetid-type Porifera (Demospongiae). Treatise Online 20: 1–79.

West, R.R. 2011b. Part E, Revised, Volume 4, Chapter 2C: Classification of the fossil and living hypercalcified chaetetid-type Porifera (Demospongiae). Treatise Online 22: 1–24.

Zhang, Y.L., Gong, E.P., Wilson, M.A., Guan, C.Q., Sun, B.L. and Chang, H.L. 2009. Paleoecology of a Pennsylvanian encrusting colonial rugose coral in South Guizhou, China. Palaeogeography, Palaeoclimatology, Palaeoecology 280: 507-516.

Zhang, Y.L., Gong, E.P., Wilson, M.A., Guan, C.Q.. and Sun, B.L. 2010. A large coral reef in the Pennsylvanian of Ziyun County, Guizhou (South China): The substrate and initial colonization environment of reef-building corals. Journal of Asian Earth Sciences 37: 335-349.

Zhang, Y., Gong, E., Wilson, M.A., Guan, C., Chen, X., Huang, W., Wang, D. and Miao, Z. 2017. Palaeoecology of Late Carboniferous encrusting chaetetids in North China. Palaeobiodiversity and Palaeoenvironments https://doi.org/10.1007/s12549-017-0300-5

Wooster’s Fossil of the Week: Predatory trace from the Upper Cretaceous of southwestern France

September 15th, 2017

One hole in a shell is unremarkable. Several in a repeating pattern is a story. Above is a right valve (exterior) of the oyster Pycnodonte vesicularis from the Campanian (Upper Cretaceous) of southwestern France. It was collected during our fantastic summer excursion into the Type Campanian at the Archiac location, which had beautiful exposures of the Aubeterre Formation. Note the jagged hole near the center, the subject of this post.Here is the other side of the right valve (the interior). We have multiple such examples in our collection, all in right valves and all near or on what would have been the oyster’s adductor (closing) muscle attachment. (Those of you with sharp eyes may also find some sweet Rogerella borings made by  barnacles, along with several encrusting bryozoan colonies.)A closer view of the hole showing spalled shell layers. (Also more bryozoans!)
Another close view of the above hole on the other side of the valve. It appears that these holes have been produced by some hard object punching through, spalling away the edges. This is what some predators do to shelled organisms to break them apart. Pether (1995) named the “ballistic trace” resulting from stomatopod shrimp predation as Belichnus. Cadée and de Wolf (2013) extended the range of trace makers to include seagulls. In both cases the predators essentially “spear” the shell, with the ensuing hole looking rather squarish and jagged. This is one of the “fracture-shaped bioerosion traces” in the architectural analysis of Buatois et al. (2017).

In our Cretaceous examples, the culprit was most likely some type of stomatopod (a large, diverse and long-lived group) smacking its way into the oysters through the thin right valve. Striking the muscle attachment would be the quickest way of forcing the shell open to reveal all the oysters goodness. The previously oldest example of Belichnus in the fossil record is Oligocene (David, 1997), so this occurrence extends the range back to the Late Cretaceous. That’s not a big deal because the ichnotaxon (trace fossil formal name) is relatively young and those who would look for it are very few. Its stratigraphic range is still maturing.

Update: Katherine Marenco sent this great video of mantis shrimp in action, including a “smasher”.

References:

Buatois, L., Wisshak, M., Wilson, M.A. and Mángano, G. 2017. Categories of architectural designs in trace fossils: A measure of ichnodisparity. Earth-Science Reviews 164: 102-181.

Cadée, G. C. and de Wolf, P. 2013. Belichnus traces produced on shells of the bivalve Lutraria lutraria by gulls. Ichnos 20: 15-18.

David, A. 1997. Predation by muricid gastropods on Late-Oligocene (Egerian) molluscs collected from Wind Brickyard, Eger, Hungary. Malak Táj 16: 5–12

Pether, J. 1995. Belichnus new ichnogenus, a ballistic trace on mollusc shells from the Holocene of the Benguela region, South Africa. Journal of Paleontology 69: 171-181.

 

Wildfires in Montana

September 11th, 2017

Windy, warm, and dry is a good recipe for wildfires, and that has been the norm for Montana this year.  For example, from June 1 through September 4, Missoula received 2.07 inches of precipitation, less than half its average rainfall for that period.  Most of those two inches fell by June 13, early in the fire season. The average daily temperature since June 1 has been 68.9°F, or 3.3°F higher than normal.

Cumulative precipitation in 2017 since June 1 for Missoula, MT (red) compared to average (blue).

The total acreage burned according to Inciweb is a little over 1 million acres.  Wildfires are common in western states, but this has been a particularly bad year.  The area burned is about three times the size of Wayne County, OH.

Size comparison between Wayne County, Ohio, Rhode Island land area, and the 2017 burned area in Montana as of 11 Sep 2017.

The Rice Ridge fire is one of the largest fires in Montana right now, with 135,355 acres burned as of Monday morning. According to Inciweb, It is 8% contained and has 891 personnel devoted to it. This fire has also been long-lasting; it began back on July 24th from a lightning strike. Missoula is the nearest city, but the communities of Seeley Lake and Lincoln are much closer to the fire.  Officials in Lincoln, MT have been making evacuation and fire-fighting plans.

The Rice Ridge Fire as of 11 Sep 2017. Darker red indicates more intense heat. Yellow areas are under evacuation warnings, and the dashed yellow line is the “no drones” perimeter. (Adapted from https://inciweb.nwcg.gov/incident/5414/.)

Glacier National Park, already with over 16,000 acres burned from the Sprague Fire and the Adair Ridge Fire, added one more active fire to the list on Saturday when a human-caused fire over the border in Canada spread into the northwest corner of the park.  The Elder Creek fire has burned 211 acres in the USA so far, but it is considered low priority given its remote location. The Park recently lost the historic Sperry Park Chalet, built in 1914, to the flames.  With warm, dry, windy conditions expected to continue in the short-term, the fire damage for Montana and other western states is likely to increase.

Weather data from the National Centers for Environmental Information (https://www.ncdc.noaa.gov)

The annual Wooster Paleontology field trip to the Upper Ordovician (Fall 2017 version)

September 10th, 2017

It’s not that I haven’t loved all my Invertebrate Paleontology classes, but the students this year are special because there are only ten of them. Lately I’ve had up to thirty students per class which is great for many reasons, but running field trips is not one of them. With ten students we can go places buses can’t, and I can pay closer attention to what each student is experiencing. Today’s field trip to an exposure of the Upper Ordovician upper Whitewater Formation near Richmond, Indiana, was delightful. (C/W-148; N 39.78722°, W 84.90166° — which has a nice Google Maps street view.)

The stratigraphy here is very simple and well delineated by generations of geologists. All the students need to do is collect fossils. They don’t know much about them yet because the course has just started, so their collections will be the basis of ongoing preservation and identification projects. Here we see Meredith Bruch and Victoria Race (below) finding goodies, while Fox Meyer climbs up the talus pursuing fabulous fossils.

Our geological technician Nick Wiesenberg went along as a driver and an ace fossil collector with an excellent eye, which I learned about when he helped Team Minnesota last year.

Ann Wilkinson enjoys the wonders of roadside geology in the Midwest.

Here’s a nice representative slab Fox collected of the fossils at this location. Brachiopods, bryozoans, and bivalves dominate the fauna.

Every student had a tray awaiting him or her on return to Wooster.

And the students did their work. Now each needs two trays. They will begin this week washing, labeling and sorting their specimens. Then they start identifying, using among other sources the excellent Digital Atlas of Ordovician Life and Cincinnatian Strata websites.

As a bonus, below is part of the 2007 Invertebrate Paleontology class on the same outcrop. Some alumni may recognize themselves, even though they are in classical paleontological poses.

Wooster’s Fossil of the Week: A rudist clam from the Upper Cretaceous of southwestern France

September 8th, 2017

When we picked up this beautiful fossil in southwestern France this summer, Paul Taylor immediately predicted it would become a Wooster Fossil of the Week. Macy Conrad (’18), Paul and I were on our wonderful expedition in the Type Campanian (Upper Cretaceous) of France. Paul took us to a most unpromising plowed field, claiming there were fossils here from the Maurens Formation. Sure enough we found a pile of large fossils that farmers had picked from their fields. They included probably the most distinctive invertebrate organism of the Late Cretaceous: the rudist clam. Hard to believe these conical objects were clams, but such is evolution. (They have the disconcerting shape and size of other objects found in some French fields: artillery shells!)

The cone itself is the right valve of these sedentary bivalves. The capping valve is the left, as seen here from the top. (Right and left make little sense unless you think of their more traditional bivalved ancestors.) Note that this valve has a reticulate, almost lacy pattern to the shell. Rudists were filter-feeders like most bivalves, but they may have also supplemented their nutrition with photosynthetic symbionts in their mantle tissue. The holes in the top valve may have allowed sunlight to hit the upper mantle.

This stratigraphic chart, courtesy of Platel et al. (1999) via Paul Taylor, shows the Maurens Formation at the top of the Campanian in southwestern France. Our primary Campanian work in SW France is with the three units below (the Biron, Barbezieux and Aubeterre formations).

A typical heterodont clam is in the upper left of this diagram; the rest are elaborate rudist clams. In the lower right is a drawing of the type of rudist photographed above. Diagram from Schumann & Steuber (1997).

Rudists flourished in Cretaceous seas right up until the mass extinction at the end of the period. They are often characterized as reef builders, but most were probably living on soft sediment substrates, like our friend here.

References:

Gili, E., Masse, J.P. and Skelton, P.W. 1995. Rudists as gregarious sediment-dwellers, not reef-builders, on Cretaceous carbonate platforms. Palaeogeography, Palaeoclimatology, Palaeoecology 118: 245-267.

Platel, J.-P. 1996. Stratigraphie, seédimentologie et évolution géodynamique de la plate-forme carbonatée du Crétacé supérieur du nord du basin d’Aquitaine. Géologie de la France 4: 33-58.

Platel, J.-P., Faugeras, P., Mauroux, B., Spencer, C., Charnet, F., Célerier, G., Harielle, B. and Jacquement, P. 1999. Notice explicative, Carte géologie France (1/50 000), feuille Thenon, Orléans, BRGM, 128 p.

Schumann, D. and Steuber, T. 1997. Rudisten. Erfolgreiche Siedler und Riffbauer der Kreidezeit. Städte unter Wasser-2 Milliarden Jahre.-Kleine Senckenberg-Reihe 24: 117-122.

Steuber, T., Mitchell, S.F., Buhl, D., Gunter, G. and Kasper, H. U. 2002. Catastrophic extinction of Caribbean rudist bivalves at the Cretaceous-Tertiary boundary. Geology 30: 999-1002.

Unknown fossils for the Invertebrate Paleontology class at Wooster

September 1st, 2017

I start my Invertebrate Paleontology classes with an unknown fossil given to each student. I pick something I have enough examples of so that everyone gets the same species. As their first assignment, the students are asked to identify their fossils as specifically as possible using whatever method works, short of asking me or my teaching assistant. Once they’ve identified their specimens, they are then asked to provide an age and likely location of collection. The beautiful fossils above were the unknowns for this semester’s class. Do you know what they are?

________________________________

These are specimens of the trepostome bryozoan Prasopora falesi (James, 1884) from the Decorah Formation (Katian, Upper Ordovician) of Decorah, Iowa. They were collected by Rachel Wetzel (’17) as part of our Team Minnesota expedition in 2016. Four of my current students figured this out to the species level! Most knew we were in bryozoan territory.

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