Archive for the 'Uncategorized' Category

Wooster’s Fossils of the Week: The mysterious Paleozoic encrusters Ascodictyon and Allonema

September 12th, 2014

 

1 Slide01The above pair of fossils are small sclerobionts commonly found on hard substrates in shallow marine sediments through much of the Paleozoic, especially the Silurian and Devonian. Paul Taylor and I have been studying them for a few years now and our first paper on them was published this summer (Wilson and Taylor, 2014). Ascodictyon (Silurian-Carboniferous) is on the left and Allonema (Silurian-Permian) is on the right. Both are calcitic encrusters and look, at least in this view, very different from each other. We present evidence in our paper, though, that strongly suggests Ascodictyon and Allonema are actually manifestations of the same organism. What that organism is, exactly, still eludes us. We are persuaded at the very least that they are not bryozoans as originally described by Nicholson, Ulrich and Bassler. Since they are so common their identity is important for studies of fossil diversity and paleoecology.
2 Slide07The above view through a light microscope of Ascodictyon and Allonema shows the perspective paleontologists have had of these encrusters until recently. The clear calcite skeletons sitting on a calcitic brachiopod shell (this is from the Devonian of Michigan) makes for little contrast and poor resolution, and the microscope-camera combination has a very limited depth of field. The rest of the images in this post were made with a Scanning Electron Microscope (SEM) expertly operated by Paul. The difference in morphological detail is not just astonishing, it is a revolution in the study of tiny fossils like this.
3 Slide16 siluriense UKThis is a typical view of Ascodictyon. It consists of stellate clusters of inflated vesicles (like little calcite balloons) connected by thin calcitic tubes called stolons. (Ascodictyon siluriense from the Silurian of the England.)

4 Slide24 waldronense S GotlandThis is a typical Allonema. The primary form is a series of porous vesicles attached in chains like sausages. (Allonema waldronense from the Silurian of Gotland, Sweden.)

5 Slide29 Silica MIHere is where these obscure little encrusters get interesting. This is a specimen from the Silica Shale (Middle Devonian) exposed in Michigan. It was collected in a beautiful suite of fossils by that intrepid citizen scientist, Brian Bade. It consists of Allonema sausages connected to Ascodictyon stolons which are themselves connected to Ascodictyon stellate vesicle clusters. Clear evidence that Allonema and Ascodictyon are end members of a morphological continuum produced by the same organism.

7 Slide33 Silica MIA critical feature we see in this Ascodictyon/Allonema complex is the occurrence of “sockets” at the bases of vesicles like the above from the Silica Shale. These are almost certainly places where some erect portion of the organism extended above the substrate. Maybe these were feeding devices? Reproductive parts? We’ve found no trace of them.

8 Slide39 S GotlandOur hypothesis is that Allonema (left) and Ascodictyon (right, both from the Silurian of Gotland, Sweden) are the basal parts of some as yet unknown erect organism. They may have stored nutrients for the creature. We are convinced they were not bryozoans, foraminiferans, corals or sponges. Unfortunately we can only classify them as incertae sedis or Microproblematica. At some point we’ll have to figure out how to name this complex with two genera and over a dozen species.

It was fun work, and the project continues. For more detail, see Wilson and Taylor (2014).

References:

Nicholson H.A. and Etheridge R. 1877. On Ascodictyon, a new provisional and anomalous genus of Palæozoic fossils. J. Nat. Hist., Series 4, 19: 463-468.

Ulrich E.O. and Bassler R.S. 1904. A revision of the Paleozoic Bryozoa. Smith. Misc. Coll. (Quart.) 45: 256-294.

Wilson M.A. and Taylor P.D. 2001. “Pseudobryozoans” and the problem of encruster diversity in the Paleozoic. PaleoBios 21 (Supplement to No. 2): 134-135.

Wilson, M.A. and Taylor, P.D. 2014. The morphology and affinities of Allonema and Ascodictyon, two abundant Palaeozoic encrusters commonly misattributed to the ctenostome bryozoans. In: Rosso, A., Wyse Jackson, P.N. and Porter, J. (eds.), Bryozoan Studies 2013. Studi trentini di scienze naturali 94: 259-266.

Different Views of the Bog

September 9th, 2014

dr_andersonDr. Anderson describing the moisture gradient measured from the bog to the crest of the kame where the old growth remnant oak forest resides.

 

Our Climate Change class visited Browns Lake Bog with the Plant Communities and Ecosystems class from Ohio Weslyan University’s Biology class taught by Dr. Laurie Anderson. Dr. Chuck Goss, a stream ecologist from the OARDC also joined us. Both Laurie and Chuck offered new insights (and measurements) for us to consider.

One of the themes we discussed is how an influx of dust with land use change during European Settlement about 200 years ago may have “fertilized” the low nutrient bog and may have forced (is still forcing) plant communities in the bog to change. An additional challenge of to think about how the natural succession of the bog and disturbance contribute to observed changes.

header_2Sediment cores (on the tailgate) are being looked at with the thought of lithologic and plant community changes potentially being caused by clearing of the land and increased dust flux.
moisture_meterInstrument that measure soil moisture – from the wet groundwater fed bog areas to the drought-sensitive forests.

 

chuck_profileDr. Goss explains the various measurements taken in the water column beneath the floating bog and the class puzzles over how this may be reflected in the lake cores we are analyzing in the lab.

 

sundewSphagnum moss and a few Sundew plants. The moss is a primary component of the peat in our cores and the Sundew is another of the carnivorous plants that grow in the low nutrient environment of the bog.
pitchersPitcher plants – digesting insects, nice adaptation to a low nutrient environment.
teaching coringAssistant Directors of the Tree Ring Lab, Willy and Zach provide instruction on how to core a white oak to the eager group.
elmTwo folks in the group seemed to catch on (but this is an elm…).
lookBack on track with a mighty oak – Tom takes a turn.

Plot 1

We also wondered why the tree-ring width chronology from Browns Lake (above) maintains a 2-3 fold increase in growth after clearing of the land in the early 1800s. Is it because of changes in competition, carbon dioxide, nitrogen, dust, precipitation or some combination of all these. Seems to be a story in the lake and tree cores – will take some work to sort it out.

Extracting High Quality Mud from Cedar Creek Bog

September 7th, 2014

sitea1

Tom Lowell and graduate student Stephanie Allard from Cincinnati and Jacklyn Rodriguez from the University of Illinois made the trip to Morrow County to core mud from a bog adjacent to the Cedar Creek Mastodon site. We will be working with the cores in Climate Change over the next several weeks and collaborating with this team.

ext1

Extracting a meter of marl with many species of snails and even clams? We will need Dr. Wilson’s help on this.

marl

Another meter of marl.

exta

Stephanie describes the lower “glacial lake clays”, while Jacklyn takes notes.

excav1

Adjacent to our work is the excavation of the Cedar Creek Mastodon. The tripods are the sieves and the actual excavation is under the tent.

dig

A closer look at the stratigraphy in the excavation – we hope to be able to link the bog cores to this site. It may take a backhoe pit from the excavation to the bog to really understand how the stratigraphy here links with the former lake.

deep

Another meter to complete this 7-meter core. This layer represents the late glacial (~13,000 years ago) about the time when the Mastodon roamed the shores.

core_boss

The master takes another core. We look forward to the analyses of the cores that include an upper anthropogenic layer, a peat, a marl, an interval of gyttja and blue clays.

A special thanks to Clint Walker who owns the site for his interest and permission to core. Clint helped out moving our gear with his tractor and saved us hours of shuttling. Jesse Wiles provided photographs and carried gear.

2directions

 

 

Wooster’s Fossils of the Week: A hardground with rugose corals from the Upper Ordovician of southern Ohio

September 5th, 2014

Hdgd small 090114The above slab is a carbonate hardground from the Liberty Formation (Upper Ordovician) of southern Ohio. Carbonate hardgrounds are cemented seafloors, so we’re actually looking at the hard rocky bottom of an Ordovician sea. I’ve long found the idea of a hardground fascinating — it is like a bit of ancient time frozen before us. This hardground is especially interesting because of the fossils associated with it. The knobby nature of the surface is probably due to a burrow system that was preferentially cemented and then exhumed by currents that washed away the loose sediment. The intersecting tunnels, now ridges, provided numerous crannies for encrusting, boring and nestling organisms to inhabit. The high points hosted encrusting bryozoans that needed currents for their filter-feeding.

brach coral 090114There are several shelly fossils found in the low points of this hardground surface. The brachiopod in the upper left is the orthid Plaesiomys subquadrata (Hall, 1847), and the conical rugose coral in the lower right is Grewingkia canadensis (Billings, 1862)

two corals 090114Here is another detailed view of the hardground showing a second rugose coral on the left. I suspect that the corals and maybe even the brachiopod are actually in place (or “in situ” to use the fancy words). I’ve seen such occurrences before and passed them off as just examples of loose fossils rolling into holes. Here, though, we can see that both corals have the calyx (the cup in which the coral polyp was located) facing upwards. These G. canadensis corals did not attach to hard substrates like some of their cousins, but lay recumbent and curved upwards on the seafloor. What better place to do so than in the cozy hollows of a hardground?

This slab is certainly a nice vignette of a marine community nearly 450 million years old.

References:

Billings, E. 1862. New species of fossils from different parts of the Lower, Middle, and Upper Silurian rocks of Canada. Paleozoic Fossils, Volume 1, Canadian Geological Survey, p. 96-168.

Hall, J. 1847. Paleontology of New York, v. 1: Albany, State of New York, 338 p.

Palmer, T.J. 1982. Cambrian to Cretaceous changes in hardground communities. Lethaia 15: 309–323.

Wilson, M.A. and Palmer, T.J. 1992. Hardgrounds and hardground faunas. University of Wales, Aberystwyth, Institute of Earth Studies Publications 9: 1–131.

BUGGY, WET, and AWESOME

September 4th, 2014

Guest bloggers: Zach Downes & Wilson Nelson

For me, the trip started in Juneau, Alaska.  We arrived in Juneau late with a couple of things to take care of the next day before getting in a small plane and heading to Gustavus, Alaska where Glacier Bay National Park is based.  We needed food, XtraTuf boots, definitely XtraTuf boots, to meet with some folks at the University of Alaska Southeast, and to hike into the Juneau Icefield just north of town.

mendenhall

 

       The Juneau Icefield.  If you look closely you can see a person in the bottom left corner for scale

 

ice_cave

 An ice cave near the front of the Icefield.

We woke up early the next morning to catch our small plane and thirty minute flight over to Gustavus.  We were met by our pilot Kyle who was 27 and from Ohio.  He said he’d been living in Gustavus for 7 weeks after quitting his big boy job and moving there to fly planes like he’d always wanted to.  It’s always great meeting people that aren’t scared of doing something different and going after what they want.

plane

   Loading up our plane before taking off to Gustavus, Alaska

The plane ride itself was one of many memorable moments from the trip.  Neither of us had been on such a small plane before and the landscapes we flew over couldn’t have been much prettier.  We landed in Gustavus with another long laundry list of things to do before heading out into the field.  This list included organizing all of our gear, throwing our food in bear barrels, and going through the various orientations required for going out into the park.  The orientations were mostly painful to sit through as we were excited to get into the field.  All except for the bear orientation as Chris led us into the psyche of the bear through his animated, descriptive, and eye-opening teaching performance.  Once the orientations were through, we went back to the park housing for the night to get ready to head up into the east arm of the bay early in the morning.

The ride into the bay was awesome.  We met up with Captain Todd at the research boat, loaded it with our gear and kayaks, and started the two and a half hour boat ride out to Wolf Point.  A boat ride like that will go fast when you have snow-topped mountains, sea otters, and seals to look at.  With Led Zeppelin playing, Captain Todd took us all the way up the East Arm to get a look at John Muir Glacier.  What a cool guy he must have been.

zdandwilly

                      The research boat that took us out to our field site.

puffins

              Puffins we saw on the boat ride.

sea_lions

             Sea lions seen on the boat ride as well.

After getting dropped off at Wolf Point we found a place with a great view, lots of bear scat, and bear belly holes that seemed like a good spot to set up camp.  That didn’t take too long and before we knew it, Dr. Wiles was ready to go thrash up a side of Wolf Point Creek to see how easily we could make it back to a lake that would house some good wood for sampling.  It turned out not easily at all and after about an hour of crushing some pretty heinously thick brush in the rain, we decided to head back and try the other side of the creek the next day.

This crushing through thick brush became somewhat of a theme throughout the trip.  There were some sampling bright spots where we found good logs without having to do much more then kayak a short ways.  We came across about ten logs to sample at our Stump Bluffs site, and a few more down the East Arm and into Wachusett Inlet at the Wachusett River site.

We spent our nights in the field at the Wolf Point campsite and Wachusett River site. Mornings and nights were fun and there was a lot of good food and chatter with fairly tiring sample searching in between.  We drank gallons of Tang and ate way too many cookies and Reese’s Peanut Butter Cups, or maybe that was just me.  The days seemed to go by real slow, but our sixth day pickup came really fast. The time in the field was amazing. We were constantly looking at incredible landscapes, gorgeous water, and relentless bugs, with a few semi-curious bears to distract us every now and again.

willy

Glacier Bay National Park is wild in more ways then one.  It is full of life and animals and sounds that were different and completely new to me.  I have never been in a place that felt so remote and untouched.  I kept searching the ground for some piece of garbage or sign that someone had been there before.  Of course people have, but–and I hope it stays this way forever–it certainly didn’t seem like it.

flag

 

 

 

 

 

 

 

 

First Wooster paleontology field trip of the year: the glorious Ordovician of Ohio

August 31st, 2014

1CaesarCreek083114Today the Invertebrate Paleontology class at The College of Wooster drove south to one of our favorite outcrops: the Waynesville, Liberty and Whitewater Formations (= Bull Fork Formation) at the emergency spillway in Caesar Creek State Park. I enjoy taking students to this extensive exposure because it has diverse fossils, is easy for beginners, and it is hard to get lost here! The rain was unrelenting on our drive down, and it continued well past our arrival at the Visitor Center. The park manager very helpfully showed us a new park movie and gave us a talk about the Army Corps of Engineers (which runs the dam and lake). This occupied us as the rain slowed and finally ended soon after we approached the rocks. You’ll see surface water as a theme in these photos because the spillway turned into meandering streams and wetlands.

2Brachs083114Above is an example of why we visited Caesar Creek. The fossils are fantastically abundant and well preserved. The students had a simple charge: collect a diverse array of fossils, enough to fill two large bags each. They will prepare and identify their fossils throughout the semester as a field/lab exercise. Since I’ve shown these fossils many times in this blog, I’ll use the rest of the post to show off my students.

3TrevorBrianKevin083114Heading up the north end crew is (from the left) Trevor Shoemaker, Brian Merritt, and Kevin Komara. (You’ll see that I get better with the people photos as I moved south.)

4Chloe083114Chloe Wallace is here in the foreground braving the mud on her knees.

5KelliSpencer083114Kelli Baxstrom (upper left) has a nearly full bag, and the flash of purpleness in the lower right is Spencer Zeigler.

6Mary083114Mary Reinthal shows her enthusiasm for her first fossil expedition.

7Andrew083114Andrew Conaway was always easy to find on the outcrop.

8Annette083114Annette Hilton is here examining a slab full of small strophomenid brachiopods.

9Cassidy083114Cassidy Jester has a slab almost too large for her bag. Note the standing water behind her.

CurtisGalen083114Curtis Davies (back) and Galen Schwartzberg show the happiness that comes with fossil collecting (especially when the rain stops).

DanJeffKrysden083114Dan Peraza-Rudesill and Jeff Gunderson are joyfully receiving instruction from the class Teaching Assistant, Krysden Schantz.

GalenSharron083114Galen Schwartzberg (left) demonstrates that he can even find fossils here with his eyes closed as a cynical Sharron Osterman looks on. Both of these students are from Seattle, so rain is no discomfort for them. (Nor mud, in Galen’s case.)

MaeKaitlin083114Mae Kemsley and Kaitlin Starr proudly carry their first bags of fossils.

Meredith083114Meredith Mann reaches with mud-stained fingers for more fossil treasures.

William083114William Harrison is a senior who wanted to come along for the fun and to possibly add to his senior independent study materials. He was a great help with his advanced paleontological knowledge.

zPaleoGroup083114And here is the class at the end of the session with their collections. I was very pleased to see how dry everyone was. We had a window of respite for collecting because soon after lunch it began to rain again. We were only missing Julia Franceschi, who had a scheduling conflict. I’m looking forward to seeing all these fossils once they are cleaned and prepared in our paleontology lab. At the end of the semester each student will have a full report on the fossil fauna at Caesar Creek, including identifications and paleoecology.

Wooster Geologists begin the 2014-2015 school year

August 30th, 2014

GeoClub2014_585What a fine group of geologists we had at the first meeting of the College of Wooster Geology Club this week. We have an ambitious year ahead of us with outside speakers, student presentations, course field trips, and our biennial Mojave Desert Spring Expedition. Our number of geology majors has grown significantly as well, which is delightful for the faculty and staff. This great photo was taken by our departmental chair, Greg Wiles. Too bad he couldn’t have been in his own expertly composed image.

Links to our course offerings this semester can be found on our Geology Department Courses page.

Wooster’s Fossils of the Week: Orthid brachiopods from the Middle Devonian of New York

August 29th, 2014

Tropidoleptus carinatus 585On the first day of the Invertebrate Paleontology course at Wooster, I give all the students a fossil to identify as best they can. Everyone gets the same kind of specimen, and they can use any means to put as specific a name on it as possible. Most students struggle with the exercise, of course — I just want them to spend some time looking at fossils online and getting a feel for distinguishing characteristics and preservation. This week, though, one student nailed it. Meredith Mann (’16) identified the target fossil above as Tropidoleptus carinatus (Conrad, 1839) from the Middle Devonian of  New York. I suppose if I asked she could have told me it was from the Kashong Shale Member of the Moscow Formation, and that it was collected by my friend Brian Bade. Nicely done, Meredith!

Tropidoleptus carinatus (Conrad, 1839) is a member of the Orthida, an order of brachiopods that lived from the Early Cambrian up to the Permian extinction. Orthids are a difficult group to characterize because they were so variable in shell shape and form. T. carinatus, for example, is one of the few orthids to have a concavo-convex shell, meaning that one side is concave (on the right in the image above) and the other convex (left). Most orthids are biconvex, meaning that both sides are convex. (A lima bean would also be biconvex by this definition.)

I like these little brachiopods because their shells are often encrusted by wonderful little creatures like bryozoans, Allonema, Ascodictyon, and microconchids. Each shell had the potential of hosting its own little community of encrusters.

Toward an Isopach Map of the Cedar Creek Mastodon Bog

August 27th, 2014

tooth Wooster’s Climate Change class is starting the semester by  coring a bog adjacent to a recent Mastodon find in Morrow County, Ohio. The Mastodon work and related excavation is being led by Nigel Brush, University of Ashland.  Above is a photo (courtesy of Nigel Brush) of the original mastodon tooth find.

probe3After a fairly extensive theoretical conceptualization – theory was successfully brought to practice and in some cases the probe was sunk over 20 feet into the soft mud of the bog. The 20+ feet of mud is a record of environmental change over the last ~15,000 years.

probe2The lead probe team – one taking notes, one operating the GPS, one on the blunt end of the probe, and two others reflecting on the experience.

total_station                     The survey team shares a humorous moment while setting up the total station.

probe1

Sharing another humorous moment as an interdisciplinary (Archaeology/Spanish/ Geology) tile probe team – note the Mastodon Excavation Site in the background.

bog_map

The Google earth map above shows the tile probe points taken for the construction of the isopach map. The area of the tight spacing of data points in the northwest is the excavation site. Now for the contouring of the map and the determination of where the team will extract sediment cores.

tall

The auger team sampled down to almost 18 feet and discovered that the stratigraphy is blue glacial lake clays overlain by a marl (with snail shells), which is overlain by organic-rich mud. This sequence and its details will become clearer when the site is cored on 6 September.

washing_upWashing up and wondering about how the Mastodon may have met its fate along the shore of a muddy lake during the Pleistocene.

Wooster’s Fossils of the Week: Remanié fossils in the Lower Cretaceous of south-central England

August 22nd, 2014

Faringdon ammonite smThe last two editions were about a bryozoan and borings from the Faringdon Sponge Gravels (Lower Cretaceous, Upper Aptian) of south-central England. This week we have some Jurassic fossils from the same unit. That sounds a bit daft at first — Jurassic fossils in a Cretaceous unit? — until it becomes obvious that these are older fossils reworked into a younger deposit. In this case underlying Jurassic ammonites have been unearthed and tossed around with sediment in Cretaceous high-energy tidal channels. These older fossils in a younger context are called remanié, meaning they have been “rehandled” in a fancy French way.

The above image is an example of remanié in the Faringdon Sponge Gravels. It is a partial internal mold of a Jurassic ammonite. Drilled into it are several holes attributed to Early Cretaceous bivalves and called by the trace fossil name Gastrochaenolites. The ammonite fossil was eroded out of an outcrop of Jurassic rock and then bored while rolling around in what would become the Faringdon Sponge Gravels.
Ammonite frag 2 072014This is another Jurassic ammonite internal mold. The jagged lines are the sutures of the ammonite (remnants of the septal walls). This mold was phosphatized (partially replaced with phosphate) before it was reworked into the Cretaceous gravels. Many remanié fossils are phosphatized because of long exposure on the seafloor.
Ammonite frag 1 072014Finally, this is a fragment of another Jurassic ammonite internal mold in the Faringdon Sponge Gravels. It has an odd shape because it has disarticulated along the sutures. We are looking at the face of one of the septa, or at least where this septum would have been if it hadn’t dissolved. You can see some tiny borings that were made by Cretaceous polychaete worms.

In one of the cobbles in the Faringdon Sponge Gravels I found an identifiable ammonite. It was Prorasenia bowerbanki, which indicated that the cobble was derived from the Lower Kimmeridge Clay or Upper Oxfordian clays. The above ammonites are likely from the same Jurassic sequence. This means these fossils were roughly 45 million years old when they were reworked into the sponge gravels. Today it would be as if Eocene fossils were eroding out of a cliff and being incorporated within a modern sediment. When you think about it, this is a relatively common occurrence.

References:

Murray-Wallace, C V. and Belperio, A.P. 1994. Identification of remanié fossils using amino acid racemisation. Alcheringa 18: 219-227.

Pitt L.J. and Taylor P.D. 1990. Cretaceous Bryozoa from the Faringdon Sponge Gravel (Aptian) of Oxfordshire. Bulletin of the British Museum (Natural History), Geology Series, 46: 61–152.

Wells, M.R., Allison, P.A., Piggott, M.D., Hampson, G.J., Pain, C.C. and Gorman, G.J. 2010. Tidal modeling of an ancient tide-dominated seaway, part 2: the Aptian Lower Greensand Seaway of Northwest Europe. Journal of Sedimentary Research 80: 411-439.

Wilson, M.A. 1986. Coelobites and spatial refuges in a Lower Cretaceous cobble-dwelling hardground fauna. Palaeontology 29: 691-703.

Next »