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

January 27th, 2013

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.

Wooster’s Fossils of the Week: Beautiful molds on a concretion (Lower Carboniferous of Ohio)

September 30th, 2012

Kit Price (’13) was exploring a local creek on a Geomorphology course field trip north of Wooster led by Dr. Greg Wiles. Like the excellent paleontologist Kit is, her eyes continually searched the pebbles, cobbles, slabs and outcrops for that distinctive outline of something fossilian. This particular place has been in the blog before, so we know the stratigraphic and geological context of the rocks. Kit saw the curious golden brown, rounded rock above and immediately noted the presence of several fossils on its exterior. She collected it, cleaned it up, and the two of us examined the treasures.

Here is the key to what we found: A = trilobite pygidium external mold (more on this below); B = productid brachiopod dorsal valve internal mold; C = replaced bivalve shell fragment; D = productid brachiopod ventral valve external mold; E = nautiloid external mold. There are also external molds of twiggy bryozoans on the surface, but they are too small to distinguish in this view.

This rock is an ironstone concretion formed within the Meadville Member of the Cuyahoga Formation (Kinderhookian; Lower Carboniferous). It weathered out of the softer shale matrix and lay free on the creek bed. The original shells of the various fossils were dissolved away after burial, either being replaced with iron oxides (like the bivalve) or just remaining as open cavities (the molds). They represent a little survey of some of the animals that lived in this shallow, muddy seaway. Most of these fossils would have been lost to the dissolution, but the hard concretion preserved them.

The most interesting fossil here is the external mold of the trilobite pygidium (or tail piece). We don’t see these very often in Carboniferous and later rocks. The group is dwindling in advance of their final extinction at the end of the Permian period. I suspect this is the pygidium of Brachymetopus nodosus Wilson, 1979. I can only guess this, though, because only the cephalon (or head) of B. nodosus was described originally from the Meadville Member. This may be the long-missing pygidium of that species. It certainly has the little bumps that we would expect. (By the way, if you stare at the above image long enough, it appears in positive relief rather than the actual negative relief (or hole) that it is. It “pops out”, giving a view of what it may have looked like in life.)

Thanks, Kit, for such a nice view of a local Carboniferous community! It also brought back fond memories of my own local explorations as a Wooster student long, long ago.

References:

Corbett, R.G. and Manner, B.G. 1988. Geology and habitats of the Cuyahoga Valley National Recreation Area, Ohio. Ohio Journal of Science 88: 40-47.

Wilson, M.A. 1979. A new species of the trilobite Brachymetopus from the Cuyahoga Formation (Lower Mississippian) of northeastern Ohio. Journal of Paleontology 53: 221-223.

A pleasant and productive geological walk in the woods

August 1st, 2012

WOOSTER, OHIO–One of the best parts of my job is answering questions from the public about rocks and fossils. Now that I’m Secretary of the Paleontological Society, I get queries every day about something or other. (And since my brief stint on Ancient Aliens, some of my mail is predictably bizarre!) Sometimes the questions are local and students and I get to meet enthusiastic amateur geologists in the field. This morning Andy Nash (’14) and I drove a few miles north of Wooster to look at curious rocks a family had collected, and to walk through their stone-filled creek. It was delightful.

This part of Ohio has many exotic rocks scattered across its surface in Pleistocene glacial till. These rocks have their origin on the Canadian Shield and include just about every igneous and metamorphic lithology you can imagine. The family we visited had many examples of these glacial erratics. The most impressive rocks to Andy and me were pieces of the Gowganda Tillite, one of which is shown above. This rock represents lithified glacial till and is a very impressive 2.3 billion (billion-with-a-”b”) years old. This great age, plus the fact that it is a tillite within a till, makes these variegated rocks very special. The family is going to donate this one to the department, even though it will take a tractor to haul it out!

Another bonus for our brief visit was this creek exposure of the Meadville Shale Member of the Cuyahoga Formation (Kinderhookian, Carboniferous). An outcrop like this so close to campus will be useful for future paleontology field trips and maybe even an Independent Study project or two. The family that owns the land is very excited to share it. (By the way, my first paper was on a trilobite collected from the Meadville Shale in Lodi, Ohio.)

The shale outcrop is periodically broken up by floods on this little creek. Here you see scattered pieces of the gray shale, many of which have trace and body fossils in them. This shale weathers rapidly, exposing the fossils quickly. The downside of that is that the fossils are also destroyed quickly by weathering. They need the kind attention of paleontologists!

This is why we love to answer questions about geology: everyone learns in the process!

Wooster’s Fossil of the Week: fusulinids (Upper Carboniferous of Kansas)

July 8th, 2012

They look like little footballs, at least the American variety of football. Fusulinids (the name indicating the fusiform shape) are about the size and shape of wheat grains. They were marine protists (single-celled eucaryotes) that lived from the late Early Carboniferous to the end of the Permian Period. Fusulinids are foraminiferans of the Superfamily Fusulinoidea named by Valerïan Ivanovich Möller (Imperial School of Mines, St. Petersburg) in 1878. They are critical index fossils for the Late Paleozoic, and I knew them intimately during my dissertation work in southern Nevada.

The shell of a fusulinid is very complex. It is made of a granular calcite wrapped along the axis of the football in a series of chambers with internal walls. Each coil wrapped completely over the earlier coils, making the shells involute. They are most commonly studied in section to reveal the internal complexity.
Cross-section of a fusulinid (Triticites) from the Permian of Iowa.

Fusulinid evolution was dramatic for a single-celled group. The earliest varieties were very small (one or two millimeters in length), and the later ones up to five centimenters long. Their internal features also increased in complexity, making each successive new species very easy to identify. This is why they are such good indications of geological time intervals. It is this biostratigraphic value that proved most useful to me as a young graduate student working in what seemed to me to be virtually featureless Carboniferous limestones.

References:

Hageman, S.A., Kaesler, R.L. and Broadhead, T.W. 2004. Fusulinid taphonomy: encrustation, corrasion, compaction, and dissolution. Palaios 19: 610-617.

Möller, V.I., von. 1878. Die Spiral-gewundenen Foraminiferen des russischen Kohlenkalks. Mémoires de l’académie impériale des sciences de St-Pétersbourg, VII Série, Tome XXV, No. 9 et dernier.

Ross, C.A. 1967. Development of fusulinid (Foraminiferida) faunal realms. Journal of Paleontology 41: 1341-1354.

Stevens, C.H. and Stone, P. 2007. The Pennsylvanian–Early Permian Bird Spring carbonate shelf, southeastern California: Fusulinid biostratigraphy, paleogeographic evolution, and tectonic implications. Geological Society of America Special Paper 429, 82 p.

Wooster Geologist at Fort Ligonier, Pennsylvania: Choosing your ground geologically

June 5th, 2012

Fort Ligonier was built by the British in 1758 during the French and Indian War (or Seven Years’ War) along the Loyalhanna River in what is now Westmoreland County of southwestern Pennsylvania. It is a spectacular site today with a fully reconstructed fortification and an excellent museum. It gives us a chance to see how a military engineer used the local geology to build a successful fort in a difficult terrain.
The purpose of Fort Ligonier was to serve as the forward base for the capture of the French Fort Duquesne at the forks of the Ohio River. This was the most strategic site on the western frontier. The French and their Indian allies desperately wanted to preempt this attack by destroying the advancing British columns in the woods before they could assemble. The British and American colonists needed a robust road through the wilderness approaching Fort Duquesne, along with defensible strongholds. Fort Ligonier was the most critical of these positions, then, for both sides.
You would expect a fort to be built on the highest ground, yet Fort Ligonier is in a valley surrounded by commanding heights. The British knew, though, that the French and Indians did not have significant artillery in this theater. They could give up the heights so that they could use the Loyalhanna River as a defensible barrier against the inevitable infantry attacks. The site of Fort Ligonier also has small ravines on its other sides, forming a kind of moat. Most importantly, sandstone cliffs on the river side provide an unbreachable wall and an overview of the most likely approaches to the fort by the enemy. The British placed their largest cannon at the top of this cliff, surrounding them with an elaborate wooden stockade and sharpened obstacles.
The exposed rock of the Fort Ligonier cliffs is the Casselman Formation, a Late Carboniferous (about 300 million years old) mixture of shale, siltstone, sandstone and occasional coal beds. The particular unit here is a fine micaceous sandstone with cross-bedding. It was formed in an ancient river system. The cross-bedding and abundance of mica is a clue to this environment: the cross-bedding shows high-energy seasonal flooding; the mica flakes (the white grains seen below) show ebbs in water energy to near zero.
The French and Indians attacked Fort Ligonier on October 12, 1758, and very nearly took it. The British artillery sited on the sandstone cliffs was the deciding factor, though, and the besiegers retreated. Fort Ligonier swelled in population as British troops assembled for the attack on Fort Duquesne. In fact, in November 1758 it was the second largest city in Pennsylvania! (Among the British forces was the young George Washington.) The French saw the score and retreated from Fort Duquesne. The British captured this most strategic location and renamed the site “Pittsburgh”. Building and defending Fort Ligonier was key to this victory. By March 1766 the fort had served its purpose and was decommissioned.

References:

Fowler, W.M., Jr. 2005. Empires at War: The French and Indian War and the Struggle for North America, 1754–1763. Walker & Company, 360 pages.

Sipe, H.C. 1971. Fort Ligonier and Its Times. Ayer Company Publishers, 699 pages.

Stotz, C.M. 2005. Outposts of the War for Empire: The French and English in Western Pennsylvania: Their Armies, Their Forts, Their People, 1749-1764. University of Pittsburgh Press, 260 pages.

Now this is field trip weather

May 1st, 2012

WOOSTER, OHIO–It is now difficult to believe that we were measuring stratigraphic sections in a sleety thunderstorm on Saturday. Today the Tuesday lab of my Sedimentology & Stratigraphy course visited a local outcrop of the Logan Formation (Lower Carboniferous) to get more practice with stratigraphic techniques. What an enjoyable afternoon!

Students hard at work on the Logan Formation outcrop in Wooster. I’m hoping there’s no poison ivy in there.

Alex Hiatt and Cam Matesich looking very closely at the sandstone like good sedimentary geologists.

A set of male pine cones that have already distributed their pollen.

Andy Nash found this Eastern American Toad (Bufo americanus americanus) and our amphibian expert Ned Weakland captured it. Ned’s advisor Rick Lehtinen picked up a similar toad last semester on a short geology field trip. It made us feel all the more that we were in Spring at last.

Wooster’s Fossil of the Week: A scale tree root in its own soil (Upper Carboniferous of Ohio)

April 15th, 2012

Last week a local man, Larry Stauffer, brought in the above fossil for identification and then kindly donated it to the department. It is part of the root system of Lepidodendron, the “scale tree” of the Carboniferous Period. What is especially cool about it is that the rootlets, thin ribbon-like perpendicular extensions, are still attached. Usually they were lost quickly when the root was dislodged from its bed.

The well-preserved rootlets show that this bit of root is still in its original soil. Such a fossil soil is called a paleosol. These features are important in the rock record because they show ancient climate conditions, weathering profiles and sedimentation rates. Carboniferous paleosols like this are called seat earth.

The roots of Lepidodendron were given a separate generic name in 1822 by the French naturalist Alexandre Brongniart (1770-1847). He called them Stigmaria because of the regularly-spaced holes called stigmata. (You may know “stigmata” from an entirely different context!) The name was superseded by Lepidodendron once it was figured out how the roots, trunk, and leaves were connected.

Diagram of “Stigmaria ficoides”  from “Elements of Geology: The Student’s Series” by Charles Lyell (1871).

Brongniart is best known to me as one of the first biostratigraphers. He worked out the first divisions of the Tertiary Period (now known as the Paleogene and Neogene Periods) using fossils to mark time intervals. He also was the first to systematically study the trilobites at the other end of the geologic time scale. Brongniart did original geological mapping with the famous Georges Cuvier in the Paris region as well. He was a professor at the École de Mines and director of the Sèvres porcelain factories. I think he looks rather friendly in a Frenchy way.

References:

Brongniart, A. 1822. Sur la classification et la distribution des végétaux fossiles en général, et sur ceux des terrains de sédiment supérieur en particulier. Soc. Philom., Bull., pp. 25-28 and Mémoires Du Muséum d’Histoire Naturelle 8: 203–240, 297–348.

Frankenberg, J.M. and Eggert, D.A. 1969. Petrified Stigmaria from North America: Part I. Stigmaria ficoides, the underground portions of Lepidodendraceae. Palaeontographica 128B: 1–47.

Jennings, J.R. 1977. Stigmarian petrifications from the Pennsylvanian of Colorado. American Journal of Botany 64: 974-980.

Rothwell, G.W. 1984. The apex of Stigmaria (Lycopsida), rooting organ of Lepidodendrales. American Journal of Botany 71: 1031-1034.

Wooster’s Fossil of the Week: A spiriferinid brachiopod (Logan Formation, Lower Carboniferous, Ohio)

April 1st, 2012

This brachiopod is one of the most common in the Logan Formation of Wooster, Ohio, so our students know it well from outcrops in Spangler Park and the occasional excavations in town. Four specimens of Syringothyris Winchell 1863 are visible in the slab above. The critter in the upper left is an earlier Fossil of the Week: the bivalve Aviculopecten subcardiformis. This suite of fossils is about 345 million years old (Osagean Series of the Lower Carboniferous).
We can’t identify the species of these Logan Formation brachiopods because the original shells dissolved away long ago. We are left with the sediment that filled the insides of the shells, producing what paleontologists call internal molds. Syringothyris belongs to the Order Spiriferinida, a group of elongate brachiopods that are punctate, meaning there are tiny holes penetrating their shells. Unfortunately this is one feature I can’t show you with internal molds!
Alexander Winchell (1824-1891) named and first described the genus Syringothyris. He was a geology professor at the University of Michigan for decades, specializing in Lower Carboniferous stratigraphy and paleontology. He was also the state geologist of Michigan. Winchell was one of the early American Darwinists, working hard to reconcile religion and science in the United States (with decidedly mixed results!).

References:

Bork, K.B. and Malcuit, R.J. 1979. Paleoenvironments of the Cuyahoga and Logan Formations (Mississippian) of central Ohio. Geological Society of America Bulletin 90: 89–113.

Winchell, A. 1863. Descriptions of FOSSILS from the Yellow Sandstones lying beneath the “Burlington Limestone,” at Burlington, Iowa. Academy of Natural Sciences of Philadelphia, Proceedings, Ser. 2, vol. 7: 2-25.

Wooster’s Fossil of the Week: A syringoporid coral (Lower Carboniferous of Arkansas)

January 22nd, 2012

This specimen was collected from the Boone Limestone (Lower Carboniferous) near Hiwasse, Arkansas. It is a species of Syringopora Goldfuss 1826, sometimes known as the organ-pipe coral (but not the real organ pipe coral!).

Syringoporids are tabulate corals, a group that is always colonial. The corallites (tubes that contained the individual polyps) are vertical and were connected by small horizontal tubes, through which they shared common tissue. Some colonies had hundreds of corallites and built mounds up to a meter in diameter. Syringopora is the longest-ranging genus in the family, having started in the Ordovician Period and going extinct in the Permian.

Syringopora was first described by Georg August Goldfuss (1782-1848), a German paleontologist and zoologist. (Goldfuß is the proper spelling, if I can use that fancy Germanic letter.) He earned a PhD from Erlangen in 1804 and later in 1818 assumed a position teaching zoology at the University of Bonn. With Count Georg zu Münster, he wrote Petrefacta Germaniae, an ambitious attempt to catalog all the invertebrate fossils of Germany (but only got through some of the mollusks).
Georg August Goldfuß portrait by von Adolf Hohneck (1812-1879), 1841.

References:

Girty, G.H. 1915. Faunas of the Boone Limestone at St. Joe, Arkansas. U.S. Geological Survey Bulletin 598.

Goldfuß, G.A. 1826-1844. Petrefacta Germaniae. Tam ea, quae in museo universitatis Regia Borussicae Fridericiae Wilhelmiae Rhenanae servantur, quam alia quaecunque in museis Hoeninghusiano Muensteriano aliisque extant, iconibus et descriptionibus illustrata = Abbildungen und Beschreibungen der Petrefacten Deutschlands und der angränzenden Länder, unter Mitwirkung von Georg Graf zu Münster, Düsseldorf.

Nelson, S.J. 1977. Mississippian syringoporid corals, southern Canadian Rocky Mountains. Bulletin of Canadian Petroleum Geology 25: 518-581.

Wooster’s Fossil of the Week: A scale tree (Late Carboniferous of Ohio)

January 8th, 2012

We haven’t had a plant fossil in this blog for awhile. Lepidodendron Sternberg 1820, pictured above, is one of the most common fossils brought to me in Wooster by amateur collectors. It is abundant in the Upper Carboniferous (Pennsylvanian) sandstones, shales and coals in this area. People sometimes call them “fossil snakes” because they are cylindrical and appear to have scales. Appropriately, the extinct plants they represent are called “scale trees” (the literal meaning of the genus name). The fossil above is an external mold of the trunk of this tree-like organism.
A plant as large and complex as Lepidodendron has many distinctive components that are often found separate from each other in the fossil record. These parts were given their own scientific names and only relatively recently were reunited into the genus Lepidodendron. The specimen above, for example, is traditionally known as Stigmaria and represents the roots of Lepidodendron.

From Book 15 of the 4th edition of Meyers Konversationslexikon (1885-90; figure 10). Lepidodendron is the tall tree on the left.

Diagrams of the trunk leaf scars (from Lesquereux, 1879).

Lepidodendron was up to 30 meters high in Carboniferous forests. It was tree-like, branching at the top and with a trunk covered with leaf scars. They are often called “club mosses” but are really related to modern quillworts (Isoëtes). They reproduced by spores, probably only once before death.
Lepidodendron was named and described by Kaspar Maria von Sternberg (1761-1838), a Czech naturalist who virtually founded the field of paleobotany. He was a philosophy student at the University of Prague when he began to collect fossils, minerals and plants, most of which eventually formed the nucleus of the National Museum in Prague. Oddly enough, he was also a theologian and received ordination in the Catholic church. He gave up his churchly duties early, though, and worked as a full-time scientist at various institutions in Central Europe. His description of Lepidodendron came from his deep studies of the fossils associated with coal mines in Bohemia.

References:

Lesquereux, L. 1879. Atlas to the coal flora of Pennsylvania and of the Carboniferous Formation throughout the United States. Second Geological Survey of Pennsylvania, Report of Progress.

Sternberg, K.M., von. 1820-1838. Versuch einer geognostisch-botanischen Darstellung der Flora der Vorwelt.

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