Wooster’s Fossil of the Week: A chaetetid demosponge from the Upper Carboniferous of southern Nevada

June 5th, 2015

1 Chaetetid Bird Spring Upper Carboniferous Nevada 585I collected this lump of a specimen during my dissertation research in the Bird Spring Formation (Carboniferous-Permian) of southern Nevada. It was found in a richly-fossiliferous Upper Carboniferous (Moscovian) portion near Mountain Springs Pass, which is about 40 km southwest of Las Vegas. It is a chaetetid, which at the time I interpreted conventionally as a singular extinct sponge in the genus “Chaetetes“. Since then we’ve learned a lot more about chaetetids. (And about the stratigraphy of the Bird Spring Formation. I wish we had sequence stratigraphy way back then!)
2 Chaetetid Bird Spring closer Upper Carboniferous Nevada 585Excellent and thorough work, especially by Ron West, has shown that the chaetetids are “hyper-calcified” members of the Class Demospongiae of the Phylum Porifera. They are sponges indeed, but the tubular chaetetid skeleton is found in at least three orders of the demosponges, including living ones. The chaetetid skeleton, which consists of very thin tubes (as shown above) is polyphyletic, meaning several groups of organisms converged on the same form.
3 Chaetetid Bird Spring closest 585In this oblique section of a chaetetid you can see the calcitic tubules, somewhat blurred by recrystallization.
4 Chaetetid Bird Spring cross-section Upper Carboniferous Nevada 585Here is a cross-section through one of the Bird Spring chaetetids. The tubules are very thin and long, somewhat resembling hair. Chaeto– comes from the Greek chaite for “hair or hairy”.

Now we know from systematic studies that the fossil “chaetetids” cannot be classified from their tubular skeletons alone. Without evidence of the spicules (which are rarely found, or at least recognized) and original mineralogy of the skeleton (many are recrystallized or, like the one at the top of this entry, replaced with silica) we can only refer to skeletal specimens such as ours as “chaetetid hyper-calcified demosponges”.

This is enough, though, for me to reintroduce them into my Invertebrate Paleontology classes. I had removed them from the teaching collections several years ago because of the confusion as to their status. Now they are at least demosponges, hyper-calcified at that.


Almazán, E., Buitrón, B., Gómez-Espinosa, C. and Daniel Vachard. 2007. Moscovian chaetetid (boundstone) mounds in Sonora, Mexico. In: Vennin, E., Aretz, M., Boulvain, F. and Munnecke, A., eds., Facies from Palaeozoic reefs and bioaccumulations. Mémoires du Muséum national d’Histoire naturelle 195: 269–271.

Martin, L.G., Montañez, I.P. and Bishop, J.W. 2012. A paleotropical carbonate-dominated archive of Carboniferous icehouse dynamics, Bird Spring Fm., southern Great Basin, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 329: 64-82.

West, R.R. 1994. Species in coralline demosponges: Chaetetida. In: Oekentorp-Küster, P., ed., Proceedings of the VI International Symposium on Fossil Cnidaria and Porifera, Munster Cnidarian Symposium, v. 2. Courier Forschungsinstitut Senckenberg 172: 399–409.

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.

West, R.R. 2012c. Part E, Revised, Volume 4, Chapter 2D: Evolution of the hypercalcified chaetetid-type Porifera (Demospongiae). Treatise Online 35: 1–26.

Wilson, M.A. 1985. Conodont biostratigraphy and paleoenvironments at the Mississippian-Pennsylvanian boundary (Carboniferous: Namurian) in the Spring Mountains of southern Nevada. Newsletters on Stratigraphy 14: 69-80.

Wooster’s Fossil of the Week: A molded brachiopod from the Lower Carboniferous of Ohio

February 20th, 2015

Syringothyris bored Wooster CarboniferousWe haven’t had a local fossil featured on this blog for awhile. Above is an external mold of the spiriferinid brachiopod Syringothyris typa Winchell, 1863, from the Logan Formation (Lower Carboniferous, Osagean, about 345 million years old) of southeastern Wooster, Ohio. The outcrop is along the onramp from north Route 83 to east Route 30. Older Wooster geologists may remember this area was called “Little Arizona” because of the large roadcuts made for a highway bypass that was never completed. That original outcrop was destroyed several years ago, but the same rocks are exposed in this new section. This is the area where Heather Hunt (’09) did her Senior Independent Study work, and long before her Brad Leach (’83) worked with the same fossils.

The Logan Formation is primarily fine sandstone, with some subordinate conglomerates, silts and shales. It was likely deposited in the proximal portion of a prodelta at or below wavebase. The fossils in the Logan are mostly these large Syringothyris and the bivalve Aviculopecten, along with scattered crinoids, gastropods, bryozoans, nautiloids and ammonoids. This fauna needs more attention. Funny how the fossils in your own backyard are so often ignored.

This brachiopod was first buried in sediment and then the shell dissolved away, leaving an impression behind. Since it is an impression of the exterior of the shell, it is called an external mold. Curiously, all the external molds (and the internal molds as well) in the local Logan Formation have an iron-rich, burnt orange coating much finer than the fine sand matrix. This means that details are preserved that are of higher resolution than the matrix alone would allow. In the case of this fossil, that coating extended down into long, narrow borings in the shell, casting them (see below).
Syringothyris borings 585These borings are odd. Most of them are parallel to the ribs (plicae) of the brachiopod, and appear to have been excavated from the shell periphery towards its apex. This was in the opposite direction of brachiopod shell growth. I suspect they were made by boring annelid worms that started at the growing edge of the shell where the mantle ended. These traces need attention, like most other aspects of this local fossil fauna.


Ausich, W.I., Kammer, T.W. and Lane, N.G. 1979. Fossil communities of the Borden (Mississippian) delta in Indiana and northern Kentucky. Journal of Paleontology 53: 1182-1196.

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 (12 Part II): 1782-1838.

Leach, B.R. and Wilson, M.A. 1983. Statistical analysis of paleocommunities from the Logan Formation (Lower Mississippian) in Wayne County, Ohio. The Ohio Journal of Science 83: 26.

Wooster’s Fossils of the Week: Upper Carboniferous seed casts from northeastern Ohio

October 31st, 2014

Trigonocarpus trilocularis Hildreth 1838We haven’t had a paleobotanical fossil of the week for awhile, so here are a couple of nice seed casts from the Upper Carboniferous Massillon Sandstone exposed near Youngstown, Ohio. They fall within the “form genus” Trigonocarpus Brongniart 1828. A form taxon is one that may not have any systematic or evolutionary validity, but it is a convenient resting place for taxa that share a particular morphological pattern but can’t be easily classified elsewhere. Trigonocarpus consists of seed casts that are “radially symmetrical, decorticated, and have their surface marked by three prominent ridges” (Gastaldo and Matten, 1978, p. 884). These particular seeds appear to be Trigonocarpus trilocularis (Hildreth, 1837). The taxa here are problematic, of course, because these seeds belong to larger plants that have their own names.
Trigonocarpus trilocularis Hildreth 1838_585These seeds appear to be from medullosalean trees, which were small relatives of today’s cycads. They were common in wetlands throughout North America and Europe during the Carboniferous, especially the Late Carboniferous. The seeds we have were likely attached to small stalks. You can see what appears to be a circular attachment scar above.
Samuel Prescott Hildreth (1783–1863)
Dr. Samuel Prescott Hildreth (1783-1863) was a physician and historian with a keen eye for natural history, especially including fossils and rocks. He was born in Massachusetts of strong Patriot stock and moved to the dangerous territory of Ohio in 1806, settling in Marietta in 1808. Dr. Hildreth is often cited as one of the first scientists in the country west of the Alleghany Mountains. His prolific writing is fast-moving, diverse and interesting, so he must have been a great traveling companion. Dr. Hildreth served in the Ohio Legislature and was on the first Ohio Geological Survey.
HildrethNutThe above is a figure from Hildreth (1837, p. 29) showing the fossil seed he named Carpolithus trilocularis. He wrote that “[t]his nut is probably the fruit of some antediluvian palm”, which is not far from what we think now (apart from the Flood reference!).


Gastaldo, R.A. and Matten, L.C. 1978. Trigonocarpus leeanus, a new species from the Middle Pennsylvanian of southern Illinois. American Journal of Botany 65: 882-890.

Hildreth, S.P. 1837. Miscellaneous observations made during a tour in May, 1835, to the Falls of the Cuyahoga, near Lake Erie: extracted from the diary of a naturalist. American Journal of Science and Arts 31:1-84

Zodrow, E.L. 2004. Note on different kinds of attachments in trigonocarpalean (Medullosales) ovules from the Pennsylvanian Sydney Coalfield, Canada. Atlantic Geology 40: 197-206.

An Epic Geologic Competition in Cuyahoga Valley National Park

October 26th, 2014

VIRGINIA KENDALL, CUYAHOGA VALLEY NATIONAL PARK (CVNP) — What an absolutely awesome day for geology in the field!!  One of my geologic mentors once told me that “every day in the field is a day of vacation”, and today proved to be just that day.  Late October…temperatures above 60 degrees…with the fall colors everywhere!!  I could not have asked for a better day to take my Structural Geology class to “The Ledges”, part of Virginia Kendall, which is only about an hour north of campus.  Essentially, we have a National Park right in northeast Ohio, and fall is the best time to visit the area.

However, we were not just going there for a day hike.  We were on a mission.  I set up a scenario for my class:  CVNP exposes strata that in the subsurface is rich in oil and gas.  The goal for the students was to undertake a complete geologic study (including the stratigraphy, sedimentology, structure, and geomorphology) of the exposed rock in the area as an analog in order to better assess oil and gas fluid migration in the subsurface.  The class was split into two teams — seniors vs juniors.  Each team is not permitted to talk to one another about data collection, analysis, or synthesis.  Eventually, these Research and Development (R&D) Teams will share their findings with Wooster’s Production Experts (Drs. Pollock, Wiles, and Wilson) via a poster presentation later in the semester.

So, while there were literally hundreds of people out for a day hike near The Ledges, Wooster’s geologists were busy at work.  The Ledges is located just south of Happy Days Visitor Center and southeast of Peninsula, OH.

lock-29-location-map_585blogThe area between State Route 303 and Kendall Ledges Road (where there are all the green hiking trails) was our field area for the day.


The R&D Teams quickly noticed the amazing joint sets that are exposed all along The Ledges.  Essentially, we have ledges in this area due to the large fracture system (i.e., joints) affecting the rocks.  These joint sets are very easy to measure and to access due to a wonderful trail system next to the exposures in Virginia Kendall.  Notice above that these joints can be at various orientations and that those in the photo above appear to be nearly perpendicular to one another.

DSC01271_585blogLet me introduce the R&D Team of Woo seniors (’15), from left to right: Coleman Fitch, Zach Downes, Willy Nelson, and Leo Jones.  It appears that they are discussing their team’s strategy early in the day.  Michael Williams (’16), of the opposing team, is in the background.  Is Michael trying to eavesdrop on the opposing team?

DSC01269_585blogTwo members of our R&D team of Woo juniors (’16) are taking notes on this rock exposure.  Eric Parker (left) and Kaitlin Starr (right, white hat) appear to be focused on the gorgeous geology.

DSC01276_585blogThe other two members of the R&D team of Woo juniors (’16) were found hiding in a dark “slot canyon” among the joints.  Michael Williams is in the front, while Adam Silverstein is in the orange hoodie, peeking out from deep inside the “canyon”.  It appears that the juniors are separated from one another!!  It is OK; everyone had maps and GPS units, so perhaps their strategy for the day was to divide and conquer?

DSC01274_585blogWow!!  Check out this entrance to Ice Box Cave, which was formed by the intersection of several joint sets.  Unfortunately, we were not able to go any closer to the cave entrance than this, because…

DSC01273_585blog…the National Park Service is trying to save the bats, which are susceptible to White-Nose Syndrome.

DSC01278_585blogNow, I could not just end the blog without showing you such a wonderful photo.  Check out the amazing set of cross-beds that you can see exposed in the upper half of the photo.  These rocks, which are some of the youngest rocks exposed in CVNP, have been interpreted to be deposited by ancient stream deposits.  Superimposed on the cross-bedding is the characteristic honeycomb weathering that affects many of the sandstone exposures along The Ledges.  And, notice that some of the rocks appear to be more brown or rust colored; some scientists have identified limonite and pyrite (two iron-rich minerals) in the unit.

What an awesome day to be a geologist!!  Who else gets to spend a great fall day with friends, enjoy the weather, learn a little more about rocks, and measure joints along the way?  Geology rocks.



The geological setting of Fort Necessity, Pennsylvania

October 11th, 2014

Great Meadows 101114On July 3, 1754, colonial lieutenant Colonel George Washington fought and lost a small battle on this site in southwestern Pennsylvania. He and his 400 men had built this makeshift fort about a month before in anticipation of an attack by several hundred French soldiers and their Indian allies. The French were incensed at Washington and his troops after they killed or captured most of a French party at the Battle of Jumonville Glen two months before. (Accounts vary as to who was at fault for that deadly encounter as France and Britain were not at war.) The Battle of Fort Necessity was just one day long, and the British under Washington had the worst of it. Washington accepted French surrender terms and he and his men were allowed to march home. This pair of skirmishes between the French and British started the French and Indian War,  known outside of the USA as the Seven Years’ War. It quickly became a global fight between empires; in many ways it was the first modern world war. And it all started in this lonely part of the Pennsylvania country.

Washington chose to place his ill-fated fort, a reconstruction of which is shown above, in a high grassy spot known as the Great Meadows. It is situated near two passes in the Allegheny Mountains, and thus sits strategically beside major trails. Washington liked the area because there was plenty of feed for his pack animals and horses, lots of available water (too much, it turned out), and it was not in the midst of the endless woods of the region.
Screen Shot 2014-10-12 at 5.19.55 PMThis geological map of the area (from the National Park Service) shows that the fort was situated on the Upper Carboniferous Glenshaw Formation. This unit has much clay, trapping water in the thin soil above (“Philo Loam“). Further, the area is a floodplain, thus making the area a kind of wetland with grasses and sedges. Great for horse grazing, not so good for walls, buildings or trenches.
Entrenchments 101114Here we see the shallow entrenchments made by Washington and his men as they awaited attack. The clayey soil and pouring rain made a mess of these boggy trenches.

Fort inside 101114Inside the fort was a simple square building used mainly to keep supplies and wounded men dry, During the battle it was partially flooded with rainwater.

British view 101114This is the British view from the fort of the surrounding woods. Washington miscalculated his placing of the fort because the French and Indians could easily hit it with musket shots while hiding among the trees.

French Indian view 101114The French and Indian view of the hapless fort. It was easy to rain bullets on the British from the woods with little fear of the return fire.

Braddock road trace 101114Nearby is a trace of the military road Washington’s unit had blazed through the Pennsylvania woods on their way to the French Fort Duquesne in what is now Pittsburgh. The British General Edward Braddock enlarged this road the next year in his famous march to a spectacular defeat nearby (the “Battle of Monongahela“).

We can’t fault Washington too much for his choice of a fort location. He did not have the resources to clear a large patch of forest, so the meadow would have to do. He expected to be reinforced soon, so he saw the fort as a temporary measure of protection. The rain was beyond his control that July day, and the clay-rich meadow floor ensured wet misery and ruined supplies. The French surprisingly gave good terms for surrender because they were wet, too, in those woods, and they also expected more British and colonial troops would arrive soon. They feared being surrounded, and so thought their message to Washington and his countrymen had been sufficiently made. How different our world would be if the French were not so generous here in southwestern Pennsylvania!

Additional Reference:

Thornberry-Ehrlich, T. 2009. Fort Necessity National Battlefield Geologic Resources Inventory Report. Natural Resource Report NPS/NRPC/GRD/NRR—2009/082. National Park Service, Denver, Colorado.

Wooster’s Fossil of the Week: A crinoid-rich Lower Carboniferous siderite concretion (part III — those crinoids had company)

January 19th, 2014

Crinoid with platyceratid (cross-section) 585The last installment of our analysis of a Lower Carboniferous fossiliferous siderite concretion given to the department by Sam Root. In part I we looked at the crinoid stems and calices on the outside and discuss the formation of siderite concretions and the preservation of this particular assemblage. In part II we had our first look at polished sections of the concretion, taking special note of the crinoid stem morphology and its replacement by the mineral marcasite. For part III you were promised a molluscan surprise.

In the top view you can see that we have a section that fortuitously cut right through the center of a crinoid head. The stem is visible at the bottom, with the calyx and attached arms above. Crowning the calyx is a thin semi-circle of shell nestled open-side-down across the crinoid oral surface. This we can tell from the shell morphology is a parasitic platyceratid gastropod caught in place on its crinoid host. Nice.
Platyceratid Lower Carboniferous 585 annotatedThree years ago we received a fossil donation from the Calhoun family of local Lower Carboniferous fossils, including this beauty pictured above. It is a crinoid calyx (you can tell by the polygonal plates) with a cap-shaped platyceratid gastropod (Palaeocapulus acutirostre) preserved in place on top of it between the arms (now missing). I drew a line across the image to indicate the likely plane of section through a similar pair in our siderite concretion. In section the platyceratid would be recorded as a thin shelly top on the calyx.

Platyceratids have long been known as Paleozoic associates of crinoids. For many years we thought of them as simply coprophagous, meaning they were consuming crinoid feces as they exited the anus. (Awkward conversation, I know.) Careful work by Tom Baumiller (1990) showed that this arrangement (which would not have directly harmed the crinoid because it was, after all, done with the food) was likely not the case. He found trace fossil evidence that the platyceratids were likely accessing crinoid stomach contents directly through some sort of proboscis, and that these parasitized crinoids were stunted in their growth and thus directly harmed (but not killed — no good parasite wants to lose its meal ticket). Our new specimen was thus likely a miserable little crinoid, even if it didn’t have a brain to sort out its feelings.
Stem Calyx 121413As one last view of our crinoids in the concretion, look at the detail in the crinoid stem just below the calyx. The lumen is visible in the center of the stem, as well as the alternating ornaments on the columnals.

This has been a fun specimen to examine. Thanks, Sam!


Baumiller, T.K. 1990. Non-predatory drilling of Mississippian crinoids by platyceratid gastropods. Palaeontology 33: 743-748.

Donovan, S.K., and Webster, G.D. 2013. Platyceratid gastropod infestations of Neoplatycrinus Wanner (Crinoidea) from the Permian of West Timor: speculations on thecal modifications. Proceedings of the Geologists’ Association 124: 988–993.

Wooster’s Fossil of the Week: A crinoid-rich Lower Carboniferous siderite concretion (part II — the inside story)

January 12th, 2014


1 Cross-section macro 2 121413Last week’s specimen was a Lower Carboniferous fossiliferous siderite concretion from an unknown location, but likely from the Wooster area. It was donated to the department by Emeritus Geology Professor Sam Root. The concretion has beautiful crinoids preserved in it, including several stems of at least two types and three calices (crowns or heads).

I took a chance and cut the concretion with a rock saw if there were interesting features on the inside. There were indeed! In the image above you see at the bottom a cross section through a broken crinoid stem showing the articulated columnals. Above it are sections of crinoid arms (the white and grey spots) each trailing a pair of delicate pinnules (the feeding parts of the arms that carried tube feet). The arms are coming from an intact calyx that is not in the plane of the section.
2 Micro 1 121413In this closer view of the above stem we see the complex anatomy of the crinoid stem. We also see the amazing mineralogy of these specimens in a way we could not from the outside. The light brown matrix is, as we’ve said, the concretion made primarily of siderite (an iron carbonate) and clay. The crinoid columnals, which were originally made of calcite (calcium carbonate), have a silvery metallic material replacing them. This is the iron sulfide mineral marcasite. The white mineral on the inside of the stem on the left is quartz (silicon dioxide). It filled in open spaces inside the stem. To confuse things (nothing is ever easy in this business!) on the right end of the stem marcasite has filled in the cavities instead of quartz.
3 Macro close 121413This view of another stem in cross-section shows a fourth mineral in the system: calcium carbonate. It can be seen as the glassy material in the middle of the structure. It is not the original calcite that made up the columnals. It is instead a later mineral that, like the quartz and marcasite in the previous image, filled in open spaces within the stem. The marcasite, quartz and calcite are thus secondary minerals introduced to the fossil long after its burial. We call these chemical and physical changes to the original mineralogy diagenesis.
4 Fearnhead 2008 Fig 2Since this cross-section view of the crinoid stems is surprisingly complicated, here is a diagram from Fearnhead (2008, figure 2). The top is a crinoid columnal looking at its articulating surface. At the bottom is a cross-section. In our crinoids you can easily make out the lumen as a hollow space running through the center of the stems (filled with marcasite, calcite or quartz). The zygum is that portion of the columnal replaced by marcasite.

Lat week I mentioned that there was a molluscan surprise revealed upon cutting open this concretion. I’ll save that for part III of this series. Same channel next week!


Fearnhead, F.E. 2008. Towards a systematic standard approach to describing fossil crinoids, illustrated by the redescription of a Scottish Silurian Pisocrinus de Koninck. Scripta Geologica 136: 39-61.

Wooster’s Fossil of the Week: A crinoid-rich Lower Carboniferous siderite concretion (part I)

January 5th, 2014

Cobble Top 121413Last year Wooster emeritus geology professor Sam Root generously donated the above pictured siderite concretion to our paleontology collections. He had received it from a friend who didn’t know where it came from originally so we have no location. The fossils in it, though, show it is Lower Carboniferous in age and could well be from local outcrops of the Cuyahoga Formation. Sam knew this is a cool specimen so he wanted to see what we could make of it.

In the top view we can see crinoid stems running transversely across the surface. Remarkably, two crinoid calices (the arm-bearing crown of the crinoid at the top of the stem) are visible. The larger one is in the lower left. You can see the top of the stem to the farthest left, and then the calyx and attached arms to the right. The second calyx is in the upper right with the arms extending down and towards us. Finding one crinoid calyx with the delicate arms still attached is impressive; finding two in the same slab is a real treat.
Siderite Concretion Carboniferous 585Above is the other side of the concretion. Again a crinoid stem can be seen transverse across the surface. This stem is different from those on the other side, though. It does not have external sculpture, and it is separated into distinct pluricolumnals as if someone sawed through it at regular intervals.
Cobble closer 121413A closer view of the above shows yet another crinoid calyx, this one almost entirely buried in the rock with the arms extending to the surface. The arms have smaller sub-arms (pinnules) still attached. Amazing.

The concretion is made of the mineral siderite (an iron carbonate) that precipitated in fine-grained sediments around the fossils after they were buried. This usually takes place under subsurface anoxic and slightly acidic conditions. The crinoids with all their small and easily-disarticulated parts were buried quickly on the ancient seafloor, probably by a storm-induced pulse of silts and clays. The decay of their soft parts produced hydrogen sulfide gas ad carbon dioxide, triggering the geochemistry that caused the precipitation of siderite around them. The hard concretion that resulted was likely in a matrix of soft shale. The strength of the siderite kept the fossils from being crushed by the weight of sediment above. At some point many millions of years later, the shale eroded away and the concretion was freed to be picked up by some lucky person.

The crinoid stem that is divided into regular increments is interesting on its own. These segments with multiple columnals (the poker chip-like individual elements) are called pluricolumnals. They likely broke at pre-set weaknesses in the connective tissue of the living crinoid, something we see in their living descendants. This may have allowed them to break off their stems (autotomize) when in danger so that the calyx and remaining stem could float away for re-establishment elsewhere.

This concretion is so interesting that I (forgive me, Sam) could not resist cutting it open to see what is inside. The inner view is even more fascinating and will be revealed next week in part II of this story. As a teaser, it involves four minerals and a surprising mollusk!


Baumiller, T.K. and Ausich, W.I. 1992. The broken-stick model as a null hypothesis for crinoid stalk taphonomy and as a guide to the distribution of connective tissue in fossils. Paleobiology 18: 288-298.

Gautier, D.L. 1982. Siderite concretions; indicators of early diagenesis in the Gammon Shale (Cretaceous). Journal of Sedimentary Research 52: 859-871.

Wooster’s Fossil of the Week: Echinoid fragments from the Upper Carboniferous of southern Nevada

December 8th, 2013


Bird Spring Echinoid Carboniferous KC33 585This rock has been in my Invertebrate Paleontology course teaching collection since I arrived in Wooster. I collected it way back when I was doing my fieldwork for my dissertation on the biostratigraphy and paleoecology of the Bird Spring Formation (Carboniferous-Permian). This specimen comes from Kyle Canyon in the Spring Mountains west of Las Vegas, Nevada. It is from the Upper Carboniferous part of the Bird Spring. It is up this week in honor of Jeff Thompson, a new graduate student at the University of Southern California beginning his thesis work on Paleozoic echinoids.

These are spines and test plates from the echinoid Archaeocidaris M’Coy, 1844. There are many far more attractive specimens known of Archaeocidaris, so consider this a more average view of what you’re likely to find in the fossil record. The test plates are polygonal and the spines have characteristic outward-directed thorns on them. This particular specimen was disarticulated after death in a shallow, possibly lagoonal environment.
M'CoyArchaeocidaris was named by Sir Frederick M’Coy, an Irish paleontologist. (You may have seen his name as McCoy or MacCoy, but he signed with the more natively Irish M’Coy.) M’Coy was born in 1817 or 1823 (I’m shocked that there is such a discrepancy in the records) in Dublin (maybe). His father was a physician and a professor at Queen’s College, Galway. M’Coy was apparently an early starter, giving his first paper in 1838 on bird functional morphology and classification. (He was either 15 or 21.) His work history is a bit spotty. In 1841 he became Curator of the Geological Society of Dublin, but was soon replaced. In 1845 he joined the new Geological Survey of Ireland hoping to be a laboratory paleontologist. He ended up doing fieldwork but was rather bad at it, resigning from that job. Off to Cambridge he went to assist Adam Sedgwick in describing fossils. He was at last doing something in which he excelled, resulting in important publications. In 1849 M’Coy was appointed Chair of Geology and Mineralogy at Queen’s College, Belfast. His last career move was a big one: he left Ireland for Australia in 1854 to become one of the first four professors of the new University of Melbourne and director of the National Museum of Victoria (now Museum Victoria). M’Coy was very successful in these roles, although I must note that he was an advocate of importing English rabbits into Australia (you know the result) and he appeared to be a bit of an anti-Darwinist. He died in Melbourne in 1899. (Thank you to my friend Patrick Wyse Jackson for these details on M’Coy.)
Echinocrinus urii pl XXVII 1 M'Coy 1844The above is a figure in M’Coy’s 1844 work of the echinoid Echinocrinus urii (M’Coy, 1844, pl. XXVII, figure 1). There is a long story as to how this E. urii became the type species of Archaeocidaris. Andrew Smith sums it as:

Cidaris urii Fleming, 1828, p. 478, by subsequent designation of Bather 1907, p. 453. Generic name Archaeocidaris validated in Opinion 370 under plenary powers, by suppression under same powers of generic name Echinocrinus Agassiz, 1841. Opinions of the International Commission of Zoological Nomenclature 1955, 11, 301-320.

In any case, you can see how closely this illustration of an Irish fossil resembles our fossiliferous slab from the Spring Mountains. Ireland is far from Nevada now, but in the Carboniferous they were considerably closer.


M’Coy, F. 1844. A synopsis of the characters of the Carboniferous limestone fossils of Ireland. Dublin, Printed at the University Press by M.H. Gill.

Rushton, A. 1979. The real M’Coy. Lethaia 12: 226.

Wilson, M.A. 1985. Conodont biostratigraphy and paleoenvironments at the Mississippian-Pennsylvanian boundary (Carboniferous: Namurian) in the Spring Mountains of southern Nevada. Newsletters on Stratigraphy 14: 69-80.

Wyse Jackson, P.N. and Monaghan, N.T. 1994. Frederick M’Coy: an eminent Victorian palaeontologist and his synopses of Irish palaeontology of 1844 and 1846. Geology Today 10: 231-234.

Wooster’s Fossil of the Week: A crinoid calyx from the Lower Carboniferous of Iowa

November 24th, 2013

Macrocrinus verneuilianus (Shumard, 1855) 585In honor of Echinoderm Week for my Invertebrate Paleontology course, we have a beautiful crinoid calyx (or crown, or just “head”) on a slab from the Burlington Limestone (Lower Carboniferous, Osagean) found near Burlington, Iowa. I inherited this fossil when I arrived at Wooster, so I have no idea who collected it or when. The handwritten number is similar to those on many of our 19th century specimens. The sharp features of the specimen have been a bit dulled by a preparation technique that probably involved abrasives.

The crinoid is Macrocrinus verneuilianus (Shumard, 1855) of the Order Monobathrida. It is unusual in that it is preserved with its filter-feeding arms intact, along with a magnificent anal tube (see closer view below).
Macrocrinus anal chimney 585The anal tube, sometimes called an anal chimney, is just what you guessed it would be — an anus at the end of a long pipe of calcitic plates. Its primary purpose was all about hygiene. The tube allowed waste products to be whisked away far from the mouth of the crinoid, which was at the base of the arms. Some researchers suggest that the long tube served another function as well: it may have helped stabilize and direct the filter-feeding fan of outstretched arms in a stiff current, something like the tail of an airplane or a panel on a weather vane.

Macrocrinus verneuilianus (Shumard, 1855) diagramFigure of Macrocrinus verneuilianus (9) from “Paleontology of Missouri” (1884) by Charles Rollin Keyes. That long anal tube is not exaggerated!
Shumard585Benjamin Franklin Shumard (1820-1869) named Macrocrinus verneuilianus in 1855. As you might have deduced from his name, Shumard was a Pennsylvanian, having been born in Lancaster. He received his bachelor’s degree from Miami University in Oxford, Ohio, and then later earned an MD in Louisville, Kentucky, in 1843. As a young doctor in Kentucky, he began to collect fossils as a hobby. After just three years of medicine, he gave it up to pursue a career as a geologist. (Those Kentucky fossils must have been particularly fine!) By 1848 he was on geological surveys for Minnesota, Wisconsin and Iowa, and in 1850 he went on a geological survey expedition to Oregon. (Imagine that trip in 1850.) In 1853 he became the paleontologist in the Missouri Geological Survey. In 1858 he left Missouri to begin the first Geological Survey in Texas. The Civil War must have caused him considerable pain, since he was a Pennsylvanian in Texas. He moved to St. Louis and renewed his medical career in 1861. In 1869, he decided to move south to New Orleans for health reasons. The steamship he took burned to the waterline one evening north of Vicksburg. He was safely rescued, but contracted pneumonia in the process. He returned quickly to St. Louis and there died at 49 years of age. At the time of his death Shumard was president of the St. Louis Academy of Science and a member of the Geological Societies of London, France, and Vienna, and he was also a member of the academies of science in Philadelphia, Cincinnati, and New Orleans. No doubt we would have had much more scientific accomplishment from this young paleontologist had he lived longer.


Ausich, W.I. 1999. Lower Mississippian Burlington Limestone along the Mississippi River Valley in Iowa, Illinois, and Missouri, USA, p. 139-144. In: H. Hess, W.I. Ausich, C.E. Brett and M.J. Simms (eds.), Fossil Crinoids, Cambridge University Press.

Ausich, W.I. and Kammer, T.W. 2010. Generic concepts in the Batocrinidae Wachsmuth and Springer, 1881 (Class Crinoidea). Journal of Paleontology 84: 32-50.

Lane, N.G. 1963. Two new Mississippian camerate (Batocrinidae) crinoid genera. Journal of Paleontology 37: 691-702.

Shumard, B.F. 1855. Description of new species of organic remains. Missouri Geological Survey 2:185–208.

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