Wooster’s Fossils of the Week: Tiny athyridide brachiopods from the Lower Carboniferous of the West Midlands of England

September 9th, 2016

1 Hustedia radialis 585These little brachiopods were also in the recent gift package from Clive Champion, our English brachiopod expert and friend. They tested my photographic skills, being too large for our photomicroscope and at the limit of resolution for my camera with its extension tubes. They are the athyridide Hustedia radialis (Phillips, 1836) from the Chadian-Arundian Limestone (Viséan, Lower Carboniferous) exposed near Wetton, Staffordshire, England. Brachiopods of this size are often referred to as “micromorph“, with some debate as to whether they are dwarfed adults or juveniles. With this fauna the consensus is the former.

Athyridide brachiopods are “spire-bearing”, meaning they have complexly-spiraled lophophore supports (brachidia) inside their shells. The lophophore is a tentacular device that creates a water current and traps organic bits from it for nutrition. These tiny critters thus had surprisingly elaborate feeding systems. The first paleontologist to grind through these minuscule shells to sort out the twists and turns of their microscopic brachidia is a hero of science.
2 John Phillips (1800-1874)Hustedia radialis was named in 1836 by one of the most important English geologists of the 19th Century, John Phillips (1800-1874). He originally called it Terebratula radialis, a common genus name applied at the time to biconvex brachiopods with pedicle openings (the hole for the attaching stalk visible at the pointy end of the shell).
3 Geology of YorkshireHe named it in the second volume of his Geology of Yorkshire series.
4 Brachs PhillipsSee if you can find the two figures of Terebratula radialis in Plate XII of the book. (Hint: small, triangular and ribbed!)

John Phillips was born in Wiltshire in 1800. His mother was a sister of the famous William “Strata” Smith, another founding father of modern geology. Phillips father and mother died when he was only seven years old, so William Smith took over raising him, despite his genteel poverty. Phillips traveled with Smith throughout England in the course of making Smith’s famous 1815 map. Phillips had a spotty formal education, but was clearly a quick study. By 1824 he was organizing museum fossil collections in Yorkshire, and in 1826 he became keeper of the Yorkshire natural history museum. Phillips then advanced very quickly, helping organize the new British Association for the Advancement of Science, becoming a professor of geology at King’s College London, and then at the age of 34 he was elected a Fellow of the Royal Society. All the while he kept up a prodigious rate of publication. The honors and positions continued for Phillips, with him eventually becoming a Reader of Geology at Oxford University. A remarkable career with such an unpromising start.
5 Phillips 1841 160Phillips published the first geological time scale in 1841, inventing the term “Mesozoic” in the process. The above clip is from Phillips (1841, p. 160).
6 Phillips 1860 time scaleHere is his 1860 version of the geological time scale (Phillips, 1860, p. 51).

After an April 1874 dinner at All Souls College in Oxford, John Phillips fell down a flight of stone steps, dying the next day. No doubt but for this fall he would have continued producing geological work into the next decade.

References:

Brunton, C.H.C. 1984. Silicified brachiopods from the Viséan of County Fermanagh, Ireland (III). Rhynchonellids, spiriferids and terebratulids. Bulletin of the British Museum (Natural History), Geology 38: 27–130.

Brunton, C.H.C. and Champion, C. 1974. A Lower Carboniferous brachiopod fauna from the Manifold Valley, Staffordshire. Palaeontology 17: 811–840.

Mottequin, B., Sevastopulo, G. and Simon, E. 2015. Micromorph brachiopods from the late Asbian (Mississippian, Viséan) from northwest Ireland (Gleniff, County Sligo). Bulletin of Geosciences 90: 307-330.

Phillips, J. 1836. Illustrations of the geology of Yorkshire, Part 2. The mountain limestone district. 253 pp. John Murray, London.

Phillips, J. 1841. Figures and Descriptions of the Palaeozoic Fossils of Cornwall, Devon and West Somerset. 231 pp. Longman, Brown, Green and Longmans, London.

Phillips, J. 1860. Life on the earth: its origin and succession. 224 pp. Macmillan and Company, London.

7 Gould bookplateFun feature of that last reference: Google Books scanned a personal copy of Stephen Jay Gould, a famous American paleontologist and evolutionary theorist.

8 Darwin quoteOn one of the front pages is this penciled note: ‘Unreadable, dull’ – Charles Darwin to [unknown] 15/1/61. [UPDATE: See comment from Katherine Marenco below.]

A Wooster Geologist Visits Spangler Park

May 9th, 2016

Chloe1Editor’s note: The following entry was written by Chloe Wallace (’17), a student in this year’s Sedimentology & Stratigraphy course. One of our writing assignments was to write a blog post about our recent field trip to Spangler Park (also known as Wooster Memorial Park). I told the class that I would publish on this site the best entry, and Chloe won. It was a very close contest, though, with many other excellent entries. All the following words and images are Chloe’s.

Wooster, Ohio— On April 23, 2016, the Sedimentology and Stratigraphy class took a field trip to the local Wooster Memorial Park, also called Spangler Park. The goal was to study three separate outcrops, and then do a little exploring of our own.

The first stop was a short walk from the entrance to the park, specifically at 40.81475° North and 82.02383° West (above).

This outcrop contains rocks from the Logan Formation of the Lower Carboniferous. The rocks were non-laminated and of silt size, so it is made of siltstone. There are signs of a little bit of oxidation. There are also ripples present on some of the rocks, which is evidence of a shallow water environment. There were gray shale clasts within the siltstone, which were most likely deposited by storm events. The fact that some of the beds are thicker than others is more evidence of storm events because more sediment would have been deposited during storms and thinner beds would have built up during times of less activity. The bedding angles vary throughout the outcrop, also known as cross-stratification, which is more evidence that ripples and dunes were present as part of a flow regime at the time of deposition.

Chloe2Burrow fossils, which are a form of trace fossil, were left behind by deposit feeding organisms on some of the rocks. This is more evidence of a shallow, marine environment. Based on all the sedimentary structures and characteristics found at this outcrop, these rocks were deposited on the shallow shelf, below the fair weather wave base and above the storm wave base.

The Logan Formation is made up of five members, but specifically the Byer member is likely exposed here. Layers of fine sandstone and siltstones with shale sometimes inter-bedded characterize the Byer member (Hunt, 2009). Although it isn’t present in the two photos above, another member is usually deposited right below the Byer Member. It is called the Berne Member and it is composed of molasse rock, which is a quartz-rich conglomerate formed when the eroded material from continental collisions gathers in a foreland basin. In this case it is eroded material from the continental collisions that built up the Appalachians. The eroded material was then deposited to the west in the foreland basin that covers Pennsylvania and Ohio.

The second outcrop we reached was at the bottom of a gorge, along Rathburn Run, specifically at 40.81784° N and 82.02946° W. The exposure was composed of laminated grey shale from the Cuyahoga Formation. It marked a formation boundary because Logan Formation sandstone lies directly above it. This means the grey shale is older than the Logan Formation. Similar to the Logan Formation, there are trace fossils of marine burrowing organisms within the shale.

Chloe3In the above picture you can see an East-West trending joint running through the center of the Cuyahoga Formation grey shale caused by tectonic faulting, which is a phenomenon unrelated to the sedimentary structures.

Chloe4Siderite deposits were also found in some sandstone at the Rathburn run outcrop, which form after deposition, a diagenetic property. Siderite forms in anoxic environments where iron is reduced and sulfur is present. The grey shale of the Cuyahoga Formation isn’t porous enough for siderite replacement to take place, but the sandstone is.

The third outcrop was father upstream along on a cut bank, located at 40.81903° N and 82.02953° W.

Chloe5This photo is taken from across Rathburn Run, from the point bar. This outcrop is much younger in age, from the last time Ohio was affected by glaciation. During the Last Glacial Maximum, specifically the Pleistocene, glacial debris flows deposited the bottom section of the outcrop. The sediment is characterized by a fining upwards sequence and has two scales of support. Some areas of the deposit are composed of large grains within a matrix-support due to debris flow. Other areas of the deposit are composed of sandy conglomerate rock that is grain supported. Overall the sediment is poorly sorted and contains glacial erratics within the sediment, including boulders made of gneiss, granite, and some sedimentary rocks.

A channel cut through the original glacial debris flow deposit and was eventually filled in by wind-blown silt, also known as loess. Loess is characteristically different from the glacial deposit at the bottom of the outcrop. Loess breaks in sheets, which causes it to have steep angles. Overall, the history of this outcrop is that approximately 15,000 years ago debris flow events deposited the glacial sediment at the bottom of the outcrop, then a channel cut into the deposit and that channel eventually filled with eolian (wind-blown) silt.

Chloe6After venturing a little on our own, a few other students and myself came across a fourth outcrop that was from the Logan Formation at an elevation above both the Cuyahoga Formation shales and the glacial deposits. There is more evidence of jointing and cross-stratification that can be seen in the picture.

We saw two separate formations from the Lower Carboniferous during the field trip. We also were able to see another type of sedimentary deposit that was glacial and eolian in origin. Spangler Park displays and exposes a variety of sedimentary structures and sedimentary characteristics. The park can be characterized as displaying a coarsening upwards sequence with the Cuyahoga shale at the bottom, followed by the coarser siltstone and sandstone of the Logan Formation. This kind of coarsening upwards is usually evidence of either regression or progradation.

Both the Logan and Cuyahoga Formations are representative of shallow marine environments, as was seen in the evidence found at Spangler. Further research shows that the Cuyahoga Formation was deposited as part of a marine environment where the shoreline was prograding during the Kinderhookian and possibly very early Osagean (Bork and Malcuit, 1979; Matchen and Kammer, 2006). The Logan Formation followed and was deposited within a marine proximal deltaic environment during the Osagean (Hunt, 2009; Matchen and Kammer, 2006). This explains the coarsening upwards sequence and the marine sedimentary structures and fossils seen throughout the field trip.

References:

Bork, K.B., and Malcuit, R., 1979, Paleoenvironments of the Cuyahoga and Logan Formations (Mississippian) of central Ohio: Geological Society of America Bulletin II, v. 90, p. 1782-1838.

Hunt, H., 2009, Paleocommunities and Paleoenvironments of the Logan Formation (Mississippian, Osagean) of northeastern Ohio [Undergraduate thesis]: Wooster, The College of Wooster, 50 p.

Matchen, D.L., and Kammer, T.W., 2006, Incised valley fill interpretation for Mississippian Black Hand Sandstone, Appalachian Basin, USA: Implications for glacial eustasy at Kinderhookian-Osagean (Tn2-Tn3) boundary: Sedimentary Geology, v. 191, 89-113.

Sedimentology & Stratigraphy class in Wooster Memorial Park. Watch this space!

April 23rd, 2016

1 Glacial 042316This morning Wooster’s Sedimentology & Stratigraphy class visited Wooster Memorial (“Spangler”) Park for some field experience. A few of the students are shown above exploring a magnificent glacial deposit. I never did get a photo with all 21 students in it.

2 Logan Rathburn RunThe students are each writing a blog entry about the geology of this park as a writing assignment. You can see the instructions and additional images on our course page. The best entry will soon be posted in this blog under the student’s name. Above is a nice stream-side outcrop of the Logan Formation (Lower Carboniferous).

3 Trillium trail 042316It was a chilly but mercifully dry day for us. Classic early spring foliage for northeastern Ohio. [Dr. Lyn Loveless, our expert botanist, comes through in the comments: “Classic Spring Foliage – mostly (it seems from this scale) Dutchman’s Breeches, Dicentra cucullaria.  One stray Trillium.  Ah, Spring in Ohio!”]

4 Trillium grandiflorum 042316 585The most noteworthy flower this week is Trillium grandiflorum, a beautiful three-petaled white flower with six stamens.

5 Purple flower 042316This purple flower is unknown to me so far. I hope a kind expert adds its name in the comments![Lyn Loveless again is the kind commenter: “Phlox divaricata – Wild blue phlox.”]

 

Wooster’s Fossil of the Week: A crinoid stem internal mold from the Lower Carboniferous of Ohio

April 8th, 2016

crinoid internal mold 1The Biology Department at The College of Wooster is in the midst of a massive move in advance of the construction of the new Ruth Williams Hall of Life Science. The staff has been combing through old specimen collections, giving away items they don’t need for teaching or research. Among the objects are occasional fossils they gave to the Geology Department. The above specimen is one of the most curious: a combination internal and external mold of a crinoid stem from the local Lower Carboniferous rocks.

crinoid internal mold lumen copyThis is a closer view of the fossil. It is a cylindrical cavity with faint rings in a regular distribution. (These are external molds of the individual crinoid columnals.) Suspended down the axis is a segmented pillar with a stellate cross-section. (This is the internal mold of the crinoid stem lumen, a central cavity that runs down the center of the stem.) It appears that an iron-rich cement (probably siderite) filled this lumen after the death of the crinoid. The stem fragment was enveloped in a siderite concretion and the calcite stem columnals dissolved away. This leaves us with both an external mold of the stem and an internal mold of its lumen.

Carb stem 1For comparison, this is a crinoid stem fragment in its original calcite. It was found in a local Carboniferous limestone.

Carb stem 2Here are cross-sections of the same stems showing sediment-filled stellate lumens in their centers.

Wooster’s Fossil of the Week: A blastoid from the Lower Carboniferous of Illinois

August 21st, 2015

Pentremites IL 585It is sometimes hard to believe that exquisite fossils such as the above are sometimes very common. The above is a theca of the blastoid Pentremites godoni (DeFrance, 1819) found in the Lower Carboniferous (Mississippian) of Illinois. (Thanks to expert Colin Sumrall for the identification.) In some places these fossils can be picked up by the hundreds.

Blastoids are stemmed echinoderms that appeared first in the Ordovician and went extinct at the end of the Permian. They were most diverse and abundant in the shallow carbonate seas of the Lower Carboniferous, especially in North America. They are much beloved and studied fossils.
Pentremites IL basal 585The basal side of the above theca shows that blastoids had a small circular stem attachment, much like their cousins the crinoids. They extended numerous feeding appendages (brachioles) from their ambulacra (the five “petals” on the upper surface and sides) for filter-feeding. The theca is made of calcitic plates that are tightly fused together, thus ensuring they survive the vicissitudes of preservation.
Pentremites close 585In this close view of the top of the theca are five holes (spiracles) surrounding a central pit (the mouth) One spiracle (in the upper right) is larger than the others. It contains the anus and is thus called an anispiracle. The spiracles are openings into the interior of the theca, which contained a complexly-folded respiratory system called the hydrospire.

Pentremites godoni has a complicated taxonomic history. The original type specimen of the species (a specimen used as the definition of the species — a Platonic ideal form!) was destroyed in the middle of the 19th Century in a museum fire. The specimen was illustrated and described (although not named) in 1808 by James Parkinson (see below).
Screen Shot 2015-07-21 at 4.55.39 PMScreen Shot 2015-07-21 at 4.59.30 PMParkinson (1808, pl. 13) referred to this specimen as “an asterial fossil from America; probably of the nature of the encrinus.” Encrinus was a term used at the time for crinoids. Fay (1961) describes the convoluted way Parkinson’s specimen above became the type not only for the species, but also how P. godoni came to define the genus Pentremites as well. That Parkinson (1808) diagram, though, is the only image of the original specimen, and probably the first illustration of a blastoid.

References:

Atwood, J.W. and Sumrall, C.D. 2012. Morphometric investigation of the Pentremites fauna from the Glen Dean Formation, Kentucky. Journal of Paleontology 86: 813-828.

DeFrance, J.M.L. 1819. Dictionnaire des Sciences Naturelles 14, EA-EQE, p. 467.

Fay, R.O. 1961. The type of Pentremites Say. Journal of Paleontology 35: 868-873.

Parkinson, J. 1808. Organic remains of a former world. London, Noraville & Fell, v. 2, p. 235-236, pl. 13.

Waters, J.A., Horowitz, A.S. and Macurda, D.B., Jr. 1985. Ontogeny and phylogeny of the Carboniferous blastoid Pentremites. Journal of Paleontology 59: 701-712.

Wooster’s Fossil of the Week: A conulariid revisited (Lower Carboniferous of Indiana)

July 31st, 2015

Conulariid03 585

This summer I’ve been updating some of the photos I placed in the Wikipedia system (check them out here, if you like; free to use for any purpose). I was especially anxious to replace a low-resolution image I had made of an impressive conulariid (Paraconularia newberryi) from the Lower Carboniferous of Indiana. The new version is above. Since I used the same specimen as a Fossil of the Week exactly four years ago to the day, I thought I’d take advantage of a slow summer and update that earlier text for this week:

I have some affection for these odd fossils, the conulariids. When I was a student in the Invertebrate Paleontology course taught Dr. Richard Osgood, Jr., I did my research paper on them. I had recently found a specimen in the nearby Lodi City Park that was so different from anything I had seen that I wanted to know much more. I championed the then controversial idea that they were extinct scyphozoans (a type of cnidarian including most of what we call today the jellyfish). That is now the most popular placement for these creatures today, although I arrived at the same place mostly by luck and naïveté.

The specimen above is Paraconularia newberryi (Winchell) found somewhere in Indiana and added to the Wooster fossil collections before 1974. A close view (below) shows the characteristic ridges with a central seam on each side.

Conulariid01 585Conulariids range from the Ediacaran (about 550 million years ago) to the Late Triassic (about 200 million years ago). They survived three major extinctions (end-Ordovician, Late Devonian, end-Permian), which is remarkable considering the company they kept in their shallow marine environments suffered greatly. Why they went extinct in the Triassic is a mystery.

ConulataThe primary oddity about conulariids is their four-fold symmetry. They had four flat sides that came together something like an inverted and extended pyramid. The wide end was opened like an aperture, although sometimes closed by four flaps. Preservation of some soft tissues shows that tentacles extended from this opening. Their exoskeleton was made of a leathery periderm with phosphatic strengthening rods rather than the typical calcite or aragonite. (Some even preserve a kind of pearl in their interiors.) Conulariids may have spent at least part of their life cycle attached to a substrate as shown below, and maybe also later as free-swimming jellyfish-like forms.

It is the four-fold symmetry and preservation of tentacles that most paleontologists see as supporting the case for a scyphozoan placement of the conulariids. Debates continue, though, with some seeing them as belonging to a separate phylum unrelated to any cnidarians. This is what’s fun about extinct and unusual animals — so much room for speculative conversations!

References:

Driscoll, E.G. 1963. Paraconularia newberryi (Winchell) and other Lower Mississippian conulariids from Michigan, Ohio, Indiana, and Iowa. Contributions from the Museum of Palaeontology, The University of Michigan 18: 33-46.

Hughes, N.C., Gunderson, G.D. and Weedon, M.J. 2000. Late Cambrian conulariids from Wisconsin and Minnesota. Journal of Paleontology 74: 828-838.

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

Van Iten, H.T., Simoes, M.G., Marques, A.C. and Collins, A.G. 2006. Reassessment of the phylogenetic position of conulariids (?Vendian–Triassic) within the subphylum Medusozoa (Phylum Cnidaria). Journal of Systematic Palaeontology 4, 109–118.

 

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

June 12th, 2015

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

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

References:

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

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

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

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

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

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.

References:

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 spiriferid 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.

References:

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!).

References:

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.

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