Wooster’s Fossil of the Week: Encrusting tubes from the Devonian of Michigan

HederelloidSEM_DevMIThe scanning electron microscope (SEM) image above shows the tubes of the encrusting group known as hederelloids. They are among my favorite fossils. I was reminded of them recently while reading this advertisement for a novel in which, to my great surprise, hederelloids are a primary part of the plot! A mysterious black “fouling” destroys shipping. Scientists discover that it is made by a group long thought to be extinct — the hederelloids! There is even a page talking about the “science” behind the story. (Although I would think if they were serious they would spell “bryozoan” correctly.)
HederellaOH3The hederelloids are a group of colonial encrusting organisms found from the Silurian through the Permian, with possible members in the Ordovician and the Triassic (Taylor and Wilson, 2008). They were entirely marine and were most common by far on Devonian brachiopods and corals. They are “runner-like” encrusters, meaning they grew sequentially across the substrate budding out new members of the colony. Their zooids (the skeletons that contained the individuals) are usually curved and made of microprismatic calcite secreted from the inside only. (This latter feature meant they could repair damage such as boreholes with patches from the inside; see Wilson and Taylor, 2006). The specimen above is a Devonian spiriferid brachiopod from northwestern Ohio with a hederelloid colony encrusting the dorsal valve.
HedsSEMpdtDevNYHederelloids were very diverse in their time. The SEM image above (courtesy of Paul Taylor at the Natural History Museum, London) shows at least two types of hederelloid on a rugose coral from the Devonian of New York. The large tube at the bottom has several lateral buds. At the very top of the view you can see a much smaller hederelloid growing in the opposite direction.
DevonianIowaHederelloidUSNM78639The earliest workers on hederelloids thought that they were cyclostome bryozoans of some type (see Bassler, 1939). They look superficially like the common genera Corynotrypa, Cuffeyella and Stomatopora. Hederelloids, though, are significantly larger on the whole, they do not bud in the same pattern as bryozoans, and they do not have lamellar walls. Their shell microstructure and budding patterns suggests instead that they may be related to the phoronids, making them a kind of lophophorate (lophophore-bearing organism; the lophophore is a tentacular feeding device). They could probably, like bryozoans, retract the lophophore into their tubes when necessary. The above photograph shows the underside of a hederelloid colony from the Devonian of Iowa. Note the distinctive budding pattern. The scattered spirals are microconchids.

HedCloseUpDevNYThis is a nice collection of hederelloids from the Devonian of New York. Notice the diversity of sizes, shapes and budding patterns. How can you not be fascinated by such enigmatic little creatures?

References:

Bassler, R.S. 1939. The Hederelloidea. A suborder of Paleozoic cyclostomatous Bryozoa. Proceedings of the United States National Museum 87: 25-91.

Taylor, P.D. and Wilson, M.A. 2008. Morphology and affinities of hederelloid “bryozoans”, p. 301-309.  In: Hageman, S.J., Key, M.M., Jr., and Winston, J.E. (eds.), Bryozoan Studies 2007: Proceedings of the 14th International Bryozoology Conference, Boone, North Carolina, July 1-8, 2007.  Virginia Museum of Natural History Special Publication 15.

Taylor, P.D., Vinn, O. and Wilson, M.A. 2010. Evolution of biomineralization in ‘lophophorates’. Special Papers in Palaeontology 84: 317-333.

Wilson, M.A. and Taylor, P.D. 2006. Predatory drillholes and partial mortality in Devonian colonial metazoans. Geology 34:565-568.

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Wooster’s Fossil of the Week: Sea urchin bites from the Upper Cretaceous of southern Israel

GnathichnusCenomanian020413_585What you see above is a bit of oyster shell with some curious small gouges in it. The oyster is Ilymatogyra (Afrogyra) africana (Lamarck, 1801) from the En Yorqe’am Formation (Cenomanian) exposed in Hamakhtesh Hagadol, southern Israel. The deep scratches are the trace fossil Gnathichnus pentax Bromley, 1975. As you can just make out in the lower center of the image, the grooves are overlapping series of five-pointed stars. That’s what makes this trace so cool — the stars were made by the unique feeding apparatus of a regular echinoid (sea urchin).
Strongylocentrotus_purpuratus_020313_585This is the business end of the modern sea urchin Strongylocentrotus purpuratus (a preserved specimen in Wooster’s collection). You see here in the center the peristome, which is a circle of plates surrounding the mouth, with the sharp five-sided teeth protruding from the echinoid’s Aristotle’s Lantern. These animals slowly graze across hard substrates, using their teeth to scrape the surfaces for algae, fungi and adherent organisms like diatoms. The biting actions of the Aristotle’s Lantern produce the star-shaped incisions we know as the trace fossil Gnathichnus pentax.

I briefly sampled and studied an exposure of the fossiliferous En Yorqe’am Formation in 2003 during my first visit to Israel. The oyster shells in this unit provide one of the few examples of hard substrate communities in the tropics of the Late Cretaceous. The encrusters include ostreid and spondylid bivalves, the cyclostome bryozoan Stomatopora, and the agglutinating foraminiferan Acruliammina. Borings include those of barnacles (Rogerella elliptica) and sponges (Entobia aff. E. megastoma). There is also a sea urchin present (Heterodiadema lybicum) that was almost certainly the maker of the Gnathichnus pentax traces.

References:

Bromley, R.G. 1975. Comparative analysis of fossil and recent echinoid bioerosion. Palaeontology 18: 725-739.

Wilson, M.A. 2003. Paleoecology of a tropical Late Cretaceous (Cenomanian) skeletozoan community in the Negev Desert of southern Israel. Geological Society of America Abstracts with Programs 35(6): 420.

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Women scientists at Wooster, featuring Wooster Geologist Shelley Judge

Dr. Shelley Judge begins this excellent short video about women in science at Wooster:

Screen Shot 2013-02-07 at 10.20.43 AM(You have to click the link I made in the text above. Embedding a video in a blog post is beyond my skills!)

We’re proud of all the women scientists at Wooster, past, present and future!

 

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Wooster’s Fossil of the Week: A very thin coral from the Upper Ordovician of Indiana

Protaraea111712What we have above is a heliolitid coral known as Protaraea richmondensis Foerste, 1909. It has completely encrusted a gastropod shell with its thin corallum. Stephanie Jarvis, a Wooster student at the time and now a graduate student at Southern Illinois University, found this specimen during her paleontology class field trip to the Whitewater Formation exposed near Richmond, Indiana.

Protaraea is a confusing taxon to my Invertebrate Paleontology students. It is a very common encruster in their Ordovician field collections, being found on hard substrates as varied as rugose corals and orthid brachiopods. It is so thin, though, that it is hard to believe it was a colonial coral. Plus it has tiny septa (vertical partitions) in its corallites (the holes that held the polyps), very unlike most corals of the heliolitid variety. This is a group the students have to identify by matching pictures and taking our word for it.

We can’t identify the gastropod underneath. Note that it has a sinus evident in the last whorl (an open slot parallel to the coiling). The coral grew right up to the edge of this sinus, preserving it and its extension through the shell.

References:

Alexander, R.R. and Scharpf, C.D. 1990. Epizoans on Late Ordovician brachiopods from southeastern Indiana. Historical Biology 4: 179-202.

Foerste, A.F. 1909. Preliminary notes on Cincinnatian fossils. Denison University, Scientific Laboratories, Bulletin 14: 208-231.

Mõtus, M.-A. and Zaika, Y. 2012. The oldest heliolitids from the early Katian of the East Baltic region. GFF 134: 225-234.

Ospanova, N.K. 2010. Remarks on the classification system of the Heliolitida. Palaeoworld 19: 268–277.

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Stratigraphy and paleoenvironments of the Soeginina Beds (Paadla Formation, Lower Ludlow, Upper Silurian) on Saaremaa Island, Estonia (Senior Independent Study Thesis by Richa Ekka)

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Editor’s note: Senior Independent Study (I.S.) is a year-long program at The College of Wooster in which each student completes a research project and thesis with a faculty mentor.  We particularly enjoy I.S. in the Geology Department because there are so many cool things to do for both the faculty advisor and the student.  We post abstracts of each study as they become available.  The following was written by Richa Ekka, a senior geology major from Jamshedpur, India. She finished her thesis and graduated in December, so her work is the first of her class to be posted. You can see earlier blog posts from Richa’s study by clicking the Estonia tag to the right.

In July 2012, I travelled to Estonia with my advisor, Dr. Mark Wilson, a fellow Wooster geology major Jonah Novek, Dr. Bill Ausich and three geology students of The Ohio State University. It was quite an adventure with a few unexpected changes in our travel plans. Dr. Wilson and I had to spend a day in Tallinn, waiting for Jonah as his flight was delayed. Upon Jonah’s arrival we headed for the island of Saaremaa, where I carried out my research. We stayed in Kuressaare, on the southern shore of the island. I did my field research on the Soeginina Beds at Kübassaare in eastern Saaremaa.

The Kübessaare coastal area is an outcrop of the Soeginina Beds in the Paadla Formation (lowermost Ludlow) that represents a sequence of dolostones, marls, and stromatolites (see figure above). The Soeginina Beds represent rocks just above the Wenlock/Ludlow boundary, which is distinguished by a major disconformity that can be correlated to a regional regression on the paleocontinent of Baltica. The occurrence of these sedimentary structures and fauna in the Soeginina Beds provide us with evidence that there was a change in paleoenvironmental conditions from a shelfal marine environment to a restricted shallow marine setting followed by a hypersaline supratidal setting.

The base of the section has Chondrites trace fossils and marly shale that represent a shelfal marine environment. The next section on top has dolostones with Herrmannina ostracods, oncoids, and eurypterid fragments that indicate a shallow marine setting (lagoonal). The next section above has stromatolites (see figure below) that form in exposed intertidal mud flats. The topmost section has halite crystal molds that represent a hypersaline supratidal setting. Thus, we see a change from shelfal marine environment to a restricted shallow marine setting and finally to a hypersaline supratidal setting.

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Wooster’s Fossil of the Week: A twisty trace fossil (Lower Carboniferous of northern Kentucky)

My Invertebrate Paleontology students know this as Specimen #8 in the trace fossil exercises section: “the big swirly thing”. It is a representative of the ichnogenus Zoophycos Massalongo, 1855. This trace is well known to paleontologists and sedimentologists alike — it is found throughout the rock record from the Lower Cambrian to modern marine deposits. It has a variable form but is generally a set of closely-overlapping burrow systems that produce a horizontal to oblique set of spiraling lobes. It was produced by some worm-shaped organism plunging into the sediments in a repetitive way, gradually making larger and larger downward-directed swirls.

Zoophycos is a useful indicator of ancient depositional conditions. It give its name, in fact, to an ichnofacies — a set of fossils and sediments characterize of a particular environment. In the Paleozoic it is found in shallow water and slope environments; from the Mesozoic on it is known almost entirely from deep-sea sediments. Our specimen is from the Borden Formation and was found amidst turbidite deposits, so it is probably from an ancient slope system.

There has been much debate about the behavior and objectives of the organisms who made Zoophycos. The traditional view is that it was formed by an animal mining the sediment for food particles, a life mode called deposit-feeding. Some workers, though, have suggested it could have been a food cache, a sewage system, and even an agricultural garden of sorts to raise fungi for food. I think in the end the simplest explanatory model is deposit-feeding, although with such a long time range, a variety of behaviors likely produced this trace.

Zoophycos was named in 1855 by the Italian paleobotanist Abramo Bartolommeo Massalongo (1824-1860). Massalongo was a member of the faculty of medicine at the University of Padua, chairing their botany department. (Medicine had broad scope in those days!) Why was he studying this trace fossil? Like most of the early scientists who noticed trace fossils, he thought it was some kind of fossil plant.
Zoophycos villae (Massalongo, 1855, plate 2)

References:

Bromley, R.G. 1991. Zoophycos: strip mine, refuse dump, cache or sewage farm? Lethaia 24: 460-462.

Ekdale, A.A. and Lewis, D.W. 1991. The New Zealand Zoophycos revisited: morphology, ethology and paleoecology. Ichnos 1: 183-194.

Löwemark, L. 2011. Ethological analysis of the trace fossil Zoophycos: Hints from the Arctic Ocean. Lethaia 45: 290–298.

Massalongo, A. 1855. Zoophycos, novum genus Plantarum fossilum, Typis Antonellianis, Veronae, p. 45-52.

Olivero, D. 2003. Early Jurassic to Late Cretaceous evolution of Zoophycos in the French Subalpine Basin (southeastern France). Palaeogeography, Palaeoclimatology, Palaeoecology 192: 59-78.

Osgood, R.G. and Szmuc, E.J. 1972. The trace fossil Zoophycos as an indicator of water depth. Bulletin of American Paleontology 62 (271): 5-22.

Sappenfield, A., Droser, M., Kennedy, M. and Mckenzie, R. 2012. The oldest Zoophycos and implications for Early Cambrian deposit feeding. Geological Magazine 149: 1118-1123.

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Contemporary melting of northwestern glaciers: A new paper by Wooster Geologists … and the ultimate finish of an Independent Study adventure

OLYMPUS DIGITAL CAMERAWooster geology graduate Nathan Malcomb, now a scientist with the Pacific Northwest Research Station of the U.S. Forest Service, has just published an important paper with his advisor Greg Wiles in the journal Quaternary Research (affectionately known as “QR”). This work comes directly from Nathan’s Independent Study research with Greg, a project that was supported by the Henry J. Copeland Fund for Independent Study at Wooster. (A view of their field area in Valdez, southern Alaska, is shown above.) This is one part of Greg’s very productive Alaskan research program with his students.

Nathan and Greg used tree-ring series from temperature- and moisture-sensitive trees to reconstruct annual mass balances for six glaciers in the Pacific Northwest and Alaska. They show strong evidence to support their hypothesis that the retreat of these glaciers we see today is a unique event in the last several centuries. This melting is “dominated by global climate forcing”. Recent climate change is again demonstrated by careful data collection and well designed tests.

Glacier_Bay_Coring585

Sarah Appleton (’12) on one of the Alaskan coring expeditions.

Lauren_Juneau585

Lauren Vargo (’13) demonstrating excellent coring technique.

Reference:

Malcomb, N.L. and Wiles, G.C. 2013. Tree-ring-based reconstructions of North American glacier mass balance through the Little Ice Age — Contemporary warming transition. Quaternary Research (in press), http://dx.doi.org/10.1016/j.yqres.2012.11.005

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Wooster’s Pseudofossil of the Week: Manganese dendrites from Germany

We haven’t had a pseudofossil in this space for awhile. A pseudofossil is an object that is often mistaken for a fossil but is actually inorganic. The above may look like  fossil fern, but it is instead a set of beautiful manganese dendrites in the Solnhofen Limestone (Jurassic) of Germany (scale in millimeters). I put this photo on Wikipedia a long time ago as manganese dendrites. That didn’t stop one website from still using it as an example of a fossil.

Manganese dendrites are thin, branching crystals that grew over a surface in a rock or mineral. Often they are found in cracks or along bedding planes (as in the above example). These dendrites are usually some variety of manganese oxide. The minerals represented can include hollandite, coronadite, and cryptomelane. Apparently they are never pyrolusite, despite what you may see in textbooks. It is also impossible to tell the mineralogy from the shape of the dendrites alone.

How can you tell this is not a fossil plant? For one, the branches are too perfect: none overlap or are folded over or broken as you would expect in a buried three-dimensional plant. Next you’ll notice that all the branches extend from a line at the bottom of the image rather than from a single branching point. Finally, there is no distinction between branch, stem or leaf; instead it is a fractal-like distribution of tiny sharp-edged crystals.

As a bonus, check out this benefit you get from having manganese dendrites:

“Metaphysically, stones with dendrites resonate with blood vessels and nerves. They help heal the nervous system and conditions such as neuralgia. Dendrites can help with skeletal disorders, reverse capillary degeneration and stimulate the circulatory system. It is the stone of plenitude; it also helps create a peaceful environment and encourage the enjoyment of each moment. Dendrites deepen your connection to the earth and can bring stability in times of strife or confusion.”

The Stone of Plenitude! (I hope you do see my sarcasm here …)

This post, by the way, marks the completion of the second year of Wooster’s Fossils of the Week. So far we’ve had 104 posts. Check out our very first edition about a sweet auloporid coral!

References:

Potter, R.M. and Rossman, G.R. 1979. The mineralogy of manganese dendrites and coatings. American Mineralogist 64: 1219-1226.

Post, J.E. and McKeown, D.A. 2001. Characterization of manganese oxide mineralogy in rock varnish and dendrites using X-ray absorption spectroscopy. American Mineralogist 86: 701-713.

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Wooster’s Fossil of the Week: A glass sponge from the Upper Ordovician of southern Ohio

Pattersonia ulrichi Rauff, 1894_585Like all those who teach, I learn plenty from my students, sometimes with a simple question. Richa Ekka (’13) asked me last semester during a paleontology lab if the above specimen was really a trace fossil as I had labeled it. I collected this curious fossil many years ago and had assumed then and ever since that it was an odd burrow system preserved on the base of a bed of limestone. That I had no idea what kind of trace fossil it was didn’t seem to bother me. When Richa questioned the specimen, I picked it up and looked closely and saw that, indeed, it had a reticulate structure (shown below) that demonstrated it was certainly no fossil burrow. Richa was right.
Pattersonia ulrichi closerI began to search the paleontological literature for Ordovician sponges and quickly found the genus Pattersonia Miller, 1889, in the Family Pattersoniidae Miller, 1889, of the Class Hexactinellida (below). The lobes on this specimen match those of our fossil very closely, as does the more detailed reticulate structure.
Pattersonia aurita (Beecher)Pattersonia aurita (Beecher), Brannon, A.M. Peter farm, northern Fayette  County, Kentucky (from McFarlan, 1931).

After reviewing more articles, it is clear that the Wooster sponge is Pattersonia ulrichi Rauff, 1894. It has doubled our collection of Ordovician sponges. Thanks, Richa!

References:

Finks, R.M. 1967. S.A. Miller’s Paleozoic sponge families of 1889. Journal of Paleontology 41: 803-807.

McFarlan, A.C. 1931. The Ordovician fauna of Kentucky, p. 49-165, in: Jillson, W.R., ed., Paleontology of Kentucky, Kentucky Geological Survey, Frankfort, Kentucky.

Rauff, H. 1894. Palaeospongiologie. E. Schweizer-bartśche Verlagsbuchhandlung (E. Koch.).

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Wooster’s Fossil of the Week: A conulariid from the Upper Ordovician of Indiana

Conulariid123012This week’s fossil is not technically impressive: it is a rather modestly preserved conulariid from the Waynesville Formation of southern Indiana (location C/W-111). It is notable because it is one of the very few conulariids I’ve found in the Ordovician, and it gives me a chance to write about a fascinating talk three of my friends presented last month at the annual meeting of the Palaeontological Association in Dublin.

The above image is a side view of the specimen. Its identity as a conulariid is indicated by the four flat sides with gently curved ridges and the distinctive grooved corner between the two visible sides. With only this part of the conulariid visible, we can at least tentatively identify the specimen as Conularia formosa Miller & Dyer, 1878. Conulariids are most likely the polyp stages of scyphozoans (typical “jellyfish”).
CloseConulariid123012Here is a closer view of one of the sides. You can just make out a midline running parallel to the axis of the fossil slightly offsetting the ridges.
Cross1123012This is a broken cross-section through the conulariid showing the four corners and sides. Note that the fossil is symmetrical, give or take a little squishing during preservation. (The test was made of a flexible periderm, not a hard shell.)

This brings us to the presentation last month at the Palaeontological Association meeting titled: “Asymmetry in conulariid cnidarians and some other invertebrates”. It was given by Consuelo Sendino from the Natural History Museum in London, with co-authors Paul Taylor (also NHM London) and Kamil Zágoršek (Národní muzeum, Prague). The specimens below are part of a set of conulariids they studied from the Upper Ordovician (Sandbian) of the Czech Republic.
1Screen shot 2012-12-19 at 5.36.04 AMThis is Metaconularia anomala (Barrande, 1867). Note that it has a very different symmetry from the typical conulariid: it is four-sided at the base and three-sided at the top. Only a minority of specimens show this asymmetry, but why any do is a mystery.
2Screen shot 2012-12-19 at 5.36.27 AMHere are several more Metaconularia anomala specimens with various states of symmetry. All are internal molds.
3Screen shot 2012-12-19 at 5.37.02 AMThis is a summary of the symmetries present in these Ordovician conulariids. For such a simple morphology, these are surprisingly complex states. There is a pattern to this diversity: these conulariids show a kind of sinistral coiling — a directional asymmetry.

There are many questions that arise from such asymmetrical fossils. Why was the original symmetry “broken” in these individuals? Did asymmetry have adaptive value? (These aberrant individuals apparently survived to a normal size, at least.) Is this asymmetry genetically controlled or produced by the environment in some way? If there is a genetic component, has it ever had evolutionary value?

I now notice fossils that are outside normal symmetry ranges (like this Devonian brachiopod) and wonder how common and important the phenomenon is. Another paleontological wonder and mystery!

References:

Miller, S.A. and Dyer, C.B. 1878. Contributions to Palaeontology (No. 1). Journal of the Cincinnati Society of Natural History 1, no. l, p. 24-39.

Sendino, C., Zágoršek, K. and Taylor, P.D. 2012. Asymmetry in an Ordovician conulariid cnidarian. Lethaia 45: 423-431.

Van Iten, H. 1991. Evolutionary affinities of conulariids, p. 145-155; in Simonetta, A.M. and Conway Morris, S. (eds.). The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press, Cambridge.

Van Iten, H. 1992. Morphology and phylogenetic significance of the corners and midlines of the conulariid test. Palaeontology 35: 335-358.

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