Wooster’s Fossil of the Week: A tectonically-deformed Early Cambrian trilobite from southeastern California

April 10th, 2015

Olenellus terminatus whole 585This wonderful trilobite was found last month by Olivia Brown (’15), a student on the Wooster Geology Department’s glorious field trip to the Mojave Desert. Olivia collected it at Emigrant Pass in the Nopah Range of Inyo County, southeastern California. It comes from the Pyramid Shale Member of the Carrara Formation and is uppermost Lower Cambrian. It appears to be the species Olenellus terminatus Palmer, 1998. It is a great specimen because most of the body segments are still in place. At this locality we find mostly the semi-circular cephalon (the head) separated from the rest of the body. The species O. terminatus is so named because it represents the last of its famous lineage of Early Cambrian trilobites. The last time we found such a whole trilobite at this site was in 2011, with Nick Fedorchuk as the paleo star of the day.

This trilobite has been tectonically strained along its main axis, giving it a narrow look it did not possess in life. In fact, these trilobites with their semi-circular cephala make nice indicators of the strain their hosting rocks have experienced.
spines 032515 585This particular kind of trilobite has very distinctive spines, as shown in the close-up above. The long spine on the right comes from the trailing edge of the cephalon and is called a genal spine. The one in the center is a thoracic spine emerging from the third thoracic segment. The primary role of these spines was probably the obvious one: protection from predators. They may also have helped spread the weight of the animal across the substrate if they were walking across soupy mud (much like a snowshoe).

We’ve met this man before in this blog. James Hall (1811–1898) named the genus Olenellus in 1861. He was a legendary geologist, and the most prominent paleontologist of his time. He became the first state paleontologist of New York in 1841, and in 1893 he was appointed the New York state geologist. His most impressive legacy is the large number of fossil taxa he named and described, most in his Palaeontology of New York series. James Hall is in my academic heritage. His advisor was Amos Eaton (1776-1842), an American who learned his geology from Benjamin Silliman (1779-1864) at Yale. One of James Hall’s students was Charles Schuchert (1856-1942), a prominent invertebrate paleontologist. Schuchert had a student named Carl Owen Dunbar (1891-1979). Schuchert and Dunbar were coauthors of a famous geology textbook. Dunbar had a student at Yale named William B.N. Berry (1931-2011), my doctoral advisor. Thus my academic link to old man Hall above.

References:

Adams, R.D. 1995. Sequence-stratigraphy of Early-Middle Cambrian grand cycles in the Carrara Formation, southwest Basin and Range, California and Nevada, p. 277-328. In: Sequence Stratigraphy and Depositional Response to Eustatic, Tectonic and Climatic Forcing. Springer Netherlands.

Cooper, R.A. 1990. Interpretation of tectonically deformed fossils. New Zealand Journal of Geology and Geophysics 33: 321-332.

Hazzard, J.C. 1937. Paleozoic section in the Nopah and Resting Springs Mountains, Inyo County, California. California Journal of Mines and Geology 33: 273-339.

Palmer, A.R. 1998. Terminal Early Cambrian extinction of the Olenellina: Documentation from the Pioche Formation, Nevada. Journal of Paleontology 72: 650–672.

Palmer, A.R. and Halley, R.B. 1979. Physical stratigraphy and trilobite biostratigraphy of the Carrara Formation (Lower and middle Cambrian) in the southern Great Basin. U.S. Geological Survey Professional Paper 1047: 1-131.

Shah, J., Srivastava, D.C., Rastogi, V., Ghosh, R. and Pal, A. 2010. Strain estimation from single forms of distorted fossils—A computer graphics and MATLAB approach. Journal of the Geological Society of India 75: 89-97.

Wooster’s Fossil of the Week: A disturbingly familiar coral from the Middle Jurassic of southern Israel

April 3rd, 2015

Single Axosmilia side 585Our fossil this week is one I don’t share with my Invertebrate Paleontology classes until they’re ready for it. Those of us who grew up with Paleozoic fossils think we recognize it right away. Surely this is a solitary rugose coral? It has the right shape and the fine growth lines we call rugae (think “wrinkles”). This view below of the oral surface is not surprising either, unless you’re an enthusiast of septal arrangements.
Axosmilia oral view 585Instead of a rugose coral, though, this is a scleractinian coral from the Matmor Formation (Middle Jurassic, Callovian) of Hamakhtesh Hagadol, Israel. It is part of the collection of Matmor corals Annette Hilton (’17) and I are working through. This coral belongs to the genus Axosmilia Milne Edwards, 1848.
Axosmilia group 031815 585These corals are excellent examples of evolutionary convergence. The scleractinians are only very distantly related to the rugosans. They do not share a common ancestor with a calcareous skeleton, let alone a cone-shaped one like this. Instead the scleractinians like Axosmilia developed a skeleton very similar to that of the solitary rugosans, probably because they had similar life modes in similar environments, and thus similar selective forces. The rugosans, though, built their skeletons out of the mineral calcite, whereas the scleractinians use aragonite. (This specimens are calcite-replaced, like our specimen last week.) The vertical septa inside the cone are also arranged in different manners. Rugosans insert them in cycles of four (more or less), giving them a common name “tetracorals”; scleractinians have septal insertions in cycles of six, hence they are “hexacorals”. Rugose corals went extinct in the Permian; scleractinians are still with us today. Our friend Axosmillia appeared in the Jurassic and went extinct in the Cretaceous.

Rugose coral skeletons in the Paleozoic are commonly encrusted with a variety of skeletal organisms, and many are bored to some degree. I expected to see the same sclerobionts with these Jurassic equivalents, but they are clean and unbored. I suspect this means they lived semi-infaunally (meaning partially buried in the sediment).
Henri Milne-Edwards (1800–1885)Axosmilia was named by the English-French zoologist Henri Milne-Edwards (1800-1885) in the politically complex year of 1848. Henri was the twenty-seventh (!) child of an English planter from Jamaica and a Frenchwoman. He was born in Bruges, which is now part of Belgium but was then under the control of revolutionary France. Like many early 19th century scientists, Milne Edwards earned an MD degree but was seduced away from medicine by the wonders of natural history. He was a student of the most accomplished scientist of his time, Georges Cuvier, and quickly became a published expert on an amazing range of organisms, from crustaceans to lizards. The bulk of his career was spent at the Muséum National d’Histoire Naturelle in Paris. When he was 42 he was elected a foreign member of the Royal Society, receiving from them the prestigious Copley Medal in 1856. He died in Paris at the age of 85.

References:

Fürsich, F.T. and Werner, W. 1991. Palaeoecology of coralline sponge-coral meadows from the Upper Jurassic of Portugal. Paläontologische Zeitschrift 65: 35-69.

Martin-Garin, B., Lathuilière, B. and Geister, J. 2012. The shifting biogeography of reef corals during the Oxfordian (Late Jurassic). A climatic control?. Palaeogeography, Palaeoclimatology, Palaeoecology 365: 136-153.

Pandey, D.K., Ahmad, F. and Fürsich, F.T. 2000. Middle Jurassic scleractinian corals from northwestern Jordan. Beringeria 27: 3-29.

Pandey, D.K. and Fürsich, F.T. 2005. Jurassic corals from southern Tunisia. Zitteliana 45: 3-34.

Wooster’s Fossil of the Week: An encrusted scleractinian coral from the Middle Jurassic of southern Israel

March 27th, 2015

Amphiastrea Etallon 1859 Matmor Formation 585This week’s fossil is in honor of Annette Hilton (’17), who is my Sophomore Research Assistant this year. She has been diligently working through a large and difficult collection of scleractinian corals from the Matmor Formation (Middle Jurassic, Callovian) of Hamakhtesh Hagadol, Israel. These specimens were collected as parts of many paleoecological studies in our Wooster paleontology lab, so I thought it was time they received some systematic attention on their own. I knew it would be difficult, but Annette was up to the task and has done a splendid job.

The above specimen is a scleractinian coral of the genus Amphiastrea Étallon, 1859. It was collected from locality C/W-227 in the makhtesh. Considering the original was aragonite, it is remarkably preserved in a calcitized version. The large disks stuck to it are encrusting bivalves, probably of the genus Atreta.
Amphiastrea reverseHere we see the reverse with more encrusters. It is apparent that this cylindrical specimen was encrusted on all sides while it was in its erect living position, or this piece rolled around loose on the seafloor for an extended interval.
Amphiastrea serpulidOne of the encrusting bivalves was itself encrusted by a serpulid worm, which left part of its twisty calcitic tube behind.
Amphiastrea plicatulidThis thin, ghostly encruster is probably the bivalve Plicatula.
Amphiastrea close viewA close view of the corallites shows how well preserved they are on the surface of the coral. Each of these pits shows the vertical septa (walls of a sort) that were underneath the coral polyps in life. Despite this beautiful outer preservation, the interior of the specimen is mostly occupied by blocky calcite crystals.

This coral was found in a marly sediment, which explains why it is not locked into a solid piece of limestone as many Jurassic corals are. Amphiastrea apparently preferred environments with a significant amount of siliciclastic sediment (see Pandey and Fürsich, 2001, and other references below). I hope my students and I can further study this diverse and abundant coral fauna in the Matmor Formation. Annette Hilton has prepared the way.

Claude Auguste Étallon (1826-1862) named the genus Amphiastrea in 1859. He was a prominent paleontologist and geologist in his time. He was only 35 years old when he died, though, and has almost completely dropped out of the literature in English, except for the numerous invertebrate taxa he named. (There is a kind of immortality in our system of adding author’s names to taxa.) Using my Google Translator skills, I can read in the French literature that he was born to “an honest merchant family” in Luxeuil, France. He was a mathematics teacher first at collège Paul Féval à Dol-de-Bretagne and then later several other institutions. He developed a specialty in the rocks and fossils of the local Jurassic. Étallon created and published a geological map (“Carte géologique des Environs de St. Claude”), which was quite advanced for the time. The Late Jurassic turtle Plesiochelys etalloni was named after him in 1857. Auguste Étallon died suddenly of “the rupture of an aneurysm after two days of a slight indisposition” in February 1862.

Here’s to the memory of the energetic, productive and too short-lived Auguste Étallon.

References:

d’Amat, R. 1975. Étallon, Claude Auguste. Dictionnaire de Biographie Française 13: 163-164.

Löser, H. 2012. Revision of the Amphiastraeidae from the Monti D’Ocre area (Scleractinia; Early Cretaceous). Rivista Italiana di Paleontologia e Stratigrafia 118: 461-469.

Pandey, D.K., Ahmad, F. and Fürsich, F.T. 2000. Middle Jurassic scleractinian corals from northwestern Jordan. Beringeria 27: 3-29.

Pandey, D.K. and Fürsich, F.T. 2001. Environmental distribution of scleractinian corals in the Jurassic of Kachchh, western India. Journal Geological Society of India 57: 479-495.

Pandey, D.K. and Fürsich, F.T. 2005. Jurassic corals from southern Tunisia. Zitteliana 45: 3-34.

Vinn, O. and Wilson, M.A. 2010. Sabellid-dominated shallow water calcareous polychaete tubeworm association from the equatorial Tethys Ocean (Matmor Formation, Middle Jurassic, Israel). Neues Jahrbuch für Geologie und Paläontologie 258: 31-38.

Wilson, M.A., Feldman, H.R., Bowen, J.C. and Avni, Y. 2008. A new equatorial, very shallow marine sclerozoan fauna from the Middle Jurassic (late Callovian) of southern Israel. Palaeogeography, Palaeoclimatology, Palaeoecology 263: 24-29.

Wilson, M.A., Feldman, H.R. and Krivicich, E.B. 2010. Bioerosion in an equatorial Middle Jurassic coral-sponge reef community (Callovian, Matmor Formation, southern Israel). Palaeogeography, Palaeoclimatology, Palaeoecology 289: 93-101.

Wooster’s Fossil of the Week: A bored and formerly encrusting trepostome bryozoan from the Upper Ordovician of Indiana

March 20th, 2015

1 Trep Upper 030115The lump above looks like your average trepostome bryozoan from the Upper Ordovician. I collected it from the Whitewater Formation of the Cincinnatian Group at one of my favorite collecting sites near Richmond, Indiana. In this view you can just barely make out the tiny, regular holes that are the zooecia (calcitic tubes that held the bryozoan individuals — the zooids). There are bits of other fossils stuck to the outside, so it’s not particularly attractive as fossils go. (Except that all fossils are fascinating messengers in time.)

2 Trep Upper CloseWith this closer view you can see my initial interest in this particular bryozoan. Again, the regular, tiny holes are the zooecia. The larger pits are borings by worm-like, filter-feeding organisms. These borings are either in the ichnogenus Trypanites (if they are cylindrical) or Palaeosabella (if they are clavate, meaning clubbed at their distal ends). Such borings are common in all types of skeletal fossils in the Upper Ordovician — so common that they are part of the evidence for the Ordovician Bioerosion Revolution. So, let’s flip this ordinary, bored bryozoan over and see what’s underneath:

3 Trep Under 030115Here’s the main scientific beauty! We’re looking at the underside of the bryozoan. Ordinarily we’d expect to see a shell here that the bryozoan was encrusting, but the shell is gone. We’re gazing directly at the attachment surface of the bryozoan. It’s as if the colony had encrusted a sheet of glass and we’re looking right through it. The shell it was originally attached to has been removed either through dissolution (it might have been an aragonitic bivalve) or physical removal (it may have been a calcitic brachiopod). The borings are now much more prominent. They penetrated through the bryozoan into the mysterious missing shelly substrate. Some are small pits that just intersected the shell, others are horizontal as the boring organism turned at a right angle when it reached the shell and drilled along the bryozoan-shell interface. Removing the shell exposed the distal parts of these borings — parts that ordinarily would have been hidden by the encrusted shell.

4 Trep Under labeledHere is a closer, labeled view of this bryozoan basal surface. A is the earliest encruster recorded in this scenario; it is a small encrusting bryozoan that was first on the shelly substrate and then completely overgrown (or bioimmured) by the large trepostome. B shows that the trepostome was growing on a shell that already had borings from a previous encruster-borings combination that must have fallen off; these are grooves in the substrate that the trepostome filled in as it covered the shell. C is one of the many later borings that cut perpendicularly through the bryozoan and worked along the shell-bryozoan interface; as described above, only when that shelly substrate was removed would these be visible. In this surprisingly complex story, B represents an earlier version of C. We thus know that the shell was encrusted by one bryozoan, bored, and then that bryozoan was freed at its attachment (and not found in our collection). The same shell was then encrusted by this second bryozoan, which recorded the groove (or “half-borings”) made during the first encrustation.

These half-borings were first described in 2006 when my students Cordy Dennison-Budak and Jeff Bowen worked with me on them and we had a GSA abstract. Coleman Fitch is presently completing his Senior Independent Study enlarging the database for these features and developing detailed interpretations. The main implication from this work is that thick trepostome bryozoan encrusters often “popped off” shells, leaving no signs of their presence unless there were these half-borings in the shell surfaces and bryozoan undersides. Paleoecology and taphonomy on a very small scale!

References:

Taylor, P.D. 1990. Preservation of soft-bodied and other organisms by bioimmuration—a review. Palaeontology 33: 1-17.

Wilson, M.A., Dennison-Budak, W.C., and Bowen, J.C. 2006. Half-borings and missing encrusters on brachiopods in the Upper Ordovician: Implications for the paleoecological analysis of sclerobionts. Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 514.

Wilson, M.A. and Palmer, T.J. 2006. Patterns and processes in the Ordovician Bioerosion Revolution. Ichnos 13: 109-112.

Wilson, M.A., Palmer, T.J. and Taylor, P.D. 1994. Earliest preservation of soft-bodied fossils by epibiont bioimmuration: Upper Ordovician of Kentucky. Lethaia 27: 269-270.

 

Wooster’s Fossil of the Week: A new crinoid genus from the Silurian of Estonia

March 13th, 2015

Velocrinus CD-interray lateralIt is my pleasure to introduce a new Silurian crinoid genus and species: Velocrinus coniculus Ausich, Wilson & Vinn, 2015. The image above is a CD-interray lateral view of the calyx (or head), with the small anal plate in the middle-top. (This will make more sense below.) The scale bar is 2.0 mm, so this is a small fossil. It was captured by the Crinoid Master himself (my friend and colleague Bill Ausich) from the Middle Äigu Beds of the Kaugatuma Formation (Upper Silurian, Pridoli) at the Kaugatuma Cliffs of Saaremaa Island, Estonia. It is described in the latest issue of the Journal of Paleontology. Here’s a link to the abstract. (This is the first issue produced by Cambridge University Press, so we’re honored to be part of publishing history.)
Velocrinus E-ray lateralHere is another view of the calyx, this time looking laterally at the E-ray.
AusichWilsonVinn_Fig3This figure explains the calyx views we see above. It is a plate diagram of Velocrinus coniculus. Imagine it as what the crinoid would look like if we could separate all its preserved ossicles and lay them out. The radial plates are black; the anal plate is shown stippled and marked with an “X”; the other letters indicate the particular rays. The artwork, and the images above, are from Bill Ausich.

The genus Velocrinus is defined this way in the paper: “Crotalocrinitid with a calyx cone shaped, lacking stereomic overgrowths, comprised of relatively large plates; infrabasals not fused, visible in lateral view; two anal plates; primaxil minute, not visible in lateral view; fixed brachials present; free arms not laterally linked; anus on tegmen; (nature of tegmen plating unknown).” This certainly is opaque to most readers. Trust us — it separates this new genus from all described before. Velocrinus is derived from the Latin term velo, which means to cover or conceal (think “veil”). It refers to the tiny primibrachials, which are not visible in lateral view. The species name coniculus refers to the cone-shaped calyx.
Kaugatuma070511Velocrinus coniculus is known only from the Kaugatuma Cliffs locality on Saaremaa Island. This is one of my favorite outcrops in Estonia. The extensive bedding-plane exposures are rare in the region. They show hundreds of holdfasts (essentially roots) of crinoids, some very large. The deposit was a relatively high-energy carbonate sand shifting through a forest of tall crinoids rooted in the sediment. Palmer Shonk (’10) did an excellent Senior Independent Study with rocks and fossils we collected from this place. The site shown above, by the way, was the location of a Soviet amphibious landing in November 1944.
KaugatumaCrinoidStem070511This is a close look at a bedding plane of Middle Äigu Beds of the Kaugatuma Formation. The crinoid stems are robust and abundant. Oddly enough, we’re still not sure what genus is represented by the large stems and holdfasts. The calyx of Velocrinus coniculus is far too small to have been associated with them. I suppose this means we need another expedition to Estonia!

This is the 1000th post in the Wooster Geologists blog.

References:

Ausich, W.I., Wilson, M.A. and Vinn, O, 2012. Crinoids from the Silurian of western Estonia. Acta Palaeontologica Polonica 57: 613–631.

Ausich, W.I., Wilson, M.A. and Vinn, O, 2015. Wenlock and Pridoli (Silurian) crinoids from Saaremaa, western Estonia (Phylum Echinodermata). Journal of Paleontology 89: 72-81.

Wooster’s Fossil of the Week: A lucinid bivalve from the Middle Jurassic of southern Israel

March 6th, 2015

Fimbria CW265 2007 585Above is a specimen of the lucinid bivalve Fimbria sp. from the Matmor Formation (Middle Jurassic) of Makhtesh Gadol in southern Israel. I collected it in 2007 while working with Meredith Sharpe (Wooster ’08) as she pursued the fieldwork for her Independent Study project. It is a nice specimen in part because of its preservation. A closer look (below) shows very fine detail of the shell exterior.
Fimbria closeThe shell is no longer present, though. It was originally composed of the mineral aragonite, which was dissolved away, leaving an external mold that later filled in with very fine crystals of calcite. The sculpture of the shell is exquisitely reproduced; in some places even so well as to show growth lines. Many aragonitic bivalves and gastropods are preserved this way near the top of the Matmor Formation.
F fimbriata Solomon IslandsLucinid bivalves are still common today in the sea. The shell shown above is a modern Fimbria fimbriata from the Solomon Islands. They are infaunal, meaning they live burrowed in the sediment. Since they were not genetically endowed with long siphons, they use the foot to create mucus-lined tubes to the surface for access to seawater. Lucinids have an endosymbiotic relationship with sulfide-oxidizing bacteria in their gill tissues. They have a hemoglobin type that transports hydrogen sulfide to autotrophic bacteria, which in turn provide the bivalves with nutrition and enable them to survive in a variety of environments, from near deep-sea hydrothermal vents to shallow seagrass meadows.

Johann Karl Megerle von Mühlfeld (1765-1842) named Fimbria in 1811. I very much wish I had a portrait to go with that magnificent name. Megerle von Mühlfeld worked at the Naturhistorisches Museum in Vienna through the eventful Napoleonic years. He is best known for his pioneering work with insects, but he also curated the mollusk collections, which led to his description of the new Fimbria.

References:

Anderson, L.C. 2014. Relationships of internal shell features to chemosymbiosis, life position, and geometric constraints within the Lucinidae (Bivalvia), p. 49-72. In: Experimental Approaches to Understanding Fossil Organisms. Springer Netherlands.

Megerle von Mühlfeld, J.K. 1811. Entwurf eines neuen System’s der Schalthiergehäuse. Gesellschaft Naturforschender Freunde zu Berlin, Magazin 5: 38-72.

Monari, S. 2003. A new genus and species of fimbriid bivalve from the Kimmeridgian of the western Pontides, Turkey, and the phylogeny of the Jurassic Fimbriidae. Palaeontology 46: 857-884.

Morton, B. 1979. The biology and functional morphology of the coral-sand bivalve Fimbria fimbriata (Linnaeus, 1758). Records of the Australian Museum 32: 389-420.

Taylor, J.D. and Glover, E.A. 2006. Lucinidae (Bivalvia)–the most diverse group of chemosymbiotic molluscs. Zoological Journal of the Linnean Society 148: 421-438.

Wooster’s Fossil of the Week: Star-shaped crinoid columnals from the Middle Jurassic of southern Utah

February 27th, 2015

Isocrinus nicoleti Kane County 585Just a quick Fossil of the Week post. Above we see isolated columnals (stem units) of the crinoid Isocrinus nicoleti (Desor, 1845) found in the Co-Op Creek Member of the Carmel Formation (Middle Jurassic), Kane County, southern Utah. Greg Wiles recently received them as part of a donation to our department collections. They have such perfect star shapes that I had to share them here. For the full analysis, see my previous entry on columnals like these preserved in a limestone from the same location.

References:

Baumiller, T.K., Llewellyn, G., Messing, C.G. and Ausich, W.I. 1995. Taphonomy of isocrinid stalks: influence of decay and autotomy. Palaios 10: 87-95.

Tang, C.M., Bottjer, D.J. and Simms, M.J. 2000. Stalked crinoids from a Jurassic tidal deposit in western North America. Lethaia 33: 46-54.

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 Fossil of the Week: Sponge and bivalve borings from the Miocene of Spain

February 13th, 2015

Miocene Bored Cobble OutsideThis week we have a rather unimposing limestone cobble, at least from the outside. It was collected way back in 1989 by my student Genga Thavi (“Devi”) Nadaraju (’90) as part of a Keck Geology Consortium field project in southeastern Spain. It comes from the Los Banós Formation (Upper Miocene) exposed near the town of Abanilla. The holes are borings excavated into the carbonate matrix by marine animals. This cobble was tossed about in a coral reef complex that was part of the ancient Fortuna Basin.
Miocene Bored Cobble CutSeeing the cobble in cross-section makes it much more interesting. (Geologists love their rock saws!) We now see two categories of borings: one is large and flask-shaped, and the other a small network of spherical cavities. The large borings were produced by bivalves that tunneled into the limestone to make living chambers (domichnia) from which they could filter-feed. As the bivalve grew, the hole became deeper and wider. There was no escape — making and living in a boring like this is a lifetime occupation. These bivalve borings are classified as the trace fossil Gastrochaenolites lapidicus Kelly and Bromley, 1984. The smaller borings were made by clionaid demosponges that used acid to create a series of connected chambers, also for filter-feeding. These sponges could only penetrate about ten mm or so before their filtering became ineffective, so they are confined to the outer periphery of the cobble. The sponge borings are given the trace fossil ichnogenus Entobia Bronn, 1837.

On the inside surface of the largest boring (right side), encrusting tubes of a serpulid worm are just visible. This serpulid was also a filter-feeder. It took advantage of the cozy hole after the bivalve borer died and decayed. It is called a coelobite, or cavity-dweller. Serpulids would have had a rough time cementing to the outside of the cobble as it rolled around in this high-energy environment.

References:

Bronn, H.G. 1834-1838. Lethaea Geognostica (2 vols., Stuttgart).

Kelly, S.R.A. and Bromley, R.G. 1984. Ichnological nomenclature of clavate borings. Palaeontology 27: 793-807.

Mankiewicz, C. 1995. Response of reef growth to sea-level changes (late Miocene, Fortuna Basin, southeastern Spain). Palaios 10: 322-336.

Mankiewicz, C. 1996. The middle to upper Miocene carbonate complex of Níjar, Almería Province, southeastern Spain, in Franseen, E.K., Esteban, M., Ward, W.C., and Rouchy, J.-M., eds., Models for carbonate stratigraphy from Miocene reef complexes of the Mediterranean regions: Tulsa, SEPM (Society for Sedimentary Geology), p. 141-157.

Nadaraju, G.T. 1990. Borings associated with a Miocene coral reef complex, Fortuna basin, southeastern Spain. Third Keck Research Symposium in Geology (Smith College), p. 165-168.

Taylor, P.D. and Wilson, M.A. 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1-103.

Wooster’s Fossil of the Week: A Pleistocene octocoral holdfast from Sicily

February 6th, 2015

OctocoralHoldfastPleistoceneSicilyMy Italian colleague Agostina Vertino collected this beautiful specimen from the Pleistocene of Sicily and brought it to Wooster when she visited five years ago. It is the attaching base (holdfast) of the octocoral Keratoisis peloritana (Sequenza 1864). Octocorals (Subclass Octocorallia of the Class Anthozoa) are sometimes called “soft corals” because of their organic-rich, flexible skeletons. They are distinguished by polyps with eight tentacles, each of which is pinnate (feathery). Octocorals include beautiful sea fans and sea whips that require a hard substrate for stability. This particular holdfast is on a small slab of limestone.

The genus Keratoisis is known as the “bamboo coral” because it looks jointed like stalks of the plant. I collected fragments of Pleistocene Keratoisis branches during my visit to Sicily last year.
Giuseppe SeguenzaGiuseppe Seguenza (1833-1889) named the species Keratoisis peloritana. He was a Sicilian natural historian with broad interests, especially in geology. Although educated as a pharmacist, he found geology much more exciting on the volcanically active islands of the Mediterranean. He eventually became a professor of geology at the University of Messina (where the bust of him shown above resides). Italian sources say Seguenza received the famous Wollaston Medal from the Geological Society of London, but that does not appear to be true. Instead it appears that he was given “the balance of the proceeds of the Wollaston Fund” as a donation at the time the medal was awarded to Thomas Huxley (in 1876). The records of the society say that “the stipend of an Italian professor was too small to enable him to prosecute his palaeontological researches as fully as he could desire” (Woodward, 1876). Giuseppe Seguenza died in Messina at 56 years old.

References:

Di Geronimo, I., Messina, C., Rosso, A., Sanfilippo, R., Sciuto, F., and Vertino, A. 2005. Enhanced biodiversity in the deep: Early Pleistocene coral communities from southern Italy. In: Cold-Water Corals and Ecosystems, p. 61-86. Springer: Berlin, Heidelberg.

Fois, E. 1990. Stratigraphy and palaeogeography of the Capo Milazzo area (NE Sicily, Italy): clues to the evolution of the southern margin of the Tyrrhenian Basin during the Neogene. Palaeogeography, Palaeoclimatology, Palaeoecology 78: 87-108.

Langer M. 1989. The holdfast internodes and sclerites of Keratoisis melitensis Goldfuss 1826 Octocorallia in the Pliocene foraminifera marl Trubi of Milazzo Sicily Italy. Palaeontologische Zeitschrift 63: 15-24.

Woodward, H. 1876. Reports and proceedings, Geological Society of London. Geological Magazine 13: 181-182.

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