Wooster’s Fossil of the Week: One sick crinoid from the Middle Jurassic of Israel

May 11th, 2014

IsocrinidAMy first thought on seeing this distorted fossil was how much it evoked one of those Palaeolithic “Venus figurines“. It is certainly difficult to deduce that this is actually a crinoid column (or stem). It was found during my last expedition to the Middle Jurassic Matmor Formation in Makhtesh Gadol, southern Israel (location C/W-506). This particular crinoid was infected by parasites that caused the grotesque swellings of the skeletal calcite in the individual columnals (button-like sections of the column). The infection of a species of Apiocrinites in the Matmor is the subject of a paper now in press by me, Lizzie Reinthal (’14) and the pride of Ohio State University, Dr. Bill Ausich. That story will be a later Fossil of the Week entry. The specimen above, though, is different. To my surprise, it is a parasitic infection in an entirely different crinoid order.

IsocrinidBHere’s another view of the crinoid column. The top third shows some of the original star-shaped columnals in side view. This tells us that the crinoid was an isocrinid, possibly the cosmopolitan Isocrinus nicoleti. This group contains the famous and somewhat creepy crawling crinoids. We have just a handful of isocrinid stem fragments in the Matmor despite a decade of searching for a distinctive calyx (the head of the little beast). Note that the gall-like swellings have holes in them. This will be important in a later analysis of the parasitic system here.

IsocrinidCAnd now the other side of the fossil. Again, in the top part you can make out star-shaped columnals, but that distinctive outline is lost in the swollen column below. The stem must have been seriously hindered from flexing and bending with such a debilitating infection.

References:

Salamon, M.A. 2008. The Callovian (Middle Jurassic) crinoids from northern Lithuania. Paläontologische Zeitschrift 82: 269-278.

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.

Wilson, M.A., Reinthal, E.A. and Ausich, W.I. 2014. Parasitism of a new apiocrinitid crinoid species from the Middle Jurassic (Callovian) of southern Israel. Journal of Paleontology (in press).

Wooster’s Fossil of the Week: A scolecodont from the Upper Ordovician of the Cincinnati region

May 4th, 2014

Cincinnatian scolecodontThis tiny but fearsome jaw is known as a scolecodont, and they are fairly common in the Cincinnatian rocks (Upper Ordovician) in the tri-state area of Ohio, Kentucky and Indiana. The label on this particular specimen does not indicate the exact locality or stratigraphic unit, but it does give a taxonomic name: “Nereidavus varians Grinnell 1877″. More on that below.

Scolecodonts are the jaws of extinct polychaete annelid worms. They are known from the Cambrian right through the Recent, so we’re pretty sure what their functions were: grabbing prey and pulling it into the gullet of the worm. They are made of a very tough chitin (an organic material much like our fingernails) and survive well the vicissitudes of fossilization. I ran across them often when I studied conodonts, which they superficially resemble.

Polychaete mouthThe Telegraph, of all places, has some amazing SEM images of the scary end of living jawed polychaetes, one of which is shown above. (I think they colored it to look like it has blood on its teeth.) Our Ordovician jaw easily fits into this functional model.

For much more on scolecodonts, Olle Hints has a superb website devoted just to these critters, and Rich Fuchs has a very useful page on the Cincinnatian varieties.

Now as for the name of our specimen, it appears that the taxonomy of Ordovician scolecodonts is in a bit of disarray. Nereidavus Grinnell, 1877, is, according to Bergman (1991) and Eriksson (1999), a nomen dubium (dubious name) because the holotype (single primary type specimen) of the type species is lost. That specimen was from Cincinnatian strata, then referred to as “Lower Silurian”. The paratype (sort of a spare type specimen) is N. varians, the same name on the label of our specimen. Eriksson considered that species to be in the genus Ramphoprion Kielan-Jaworowska, 1962. A true diagnosis of our specimen would involve extracting it from the matrix and looking at it its dorsal (oral) surface, but that’s not going to happen. I’m plenty happy just leaving this fossil as Ramphoprion sp.

Kielan-JaworowskaThe paleontologist who named the scolecodont genus Ramphoprion is the famous and incredibly accomplished Zofia Kielan-Jaworowska (above). She is best known for her pioneering work on dinosaur-bearing deposits in Mongolia in the 1960s, but she has worked on many fossil groups from trilobites to mammals. Kielan-Jaworowska (born in 1925) received her Masters Degree in zoology and a doctorate in paleontology (aren’t many of those now) at Warsaw University. She became a professor there and was later the first woman to serve on the executive committee of the International Union of Geological Sciences. I read her 1974 book Hunting for Dinosaurs in college as an adventure tale with a strong narrative framework of science. It was inspirational, and it convinced me that paleontology was the coolest science.

References:

Bergman, C F. 1991. Revision of some Silurian paulinitid scolecodonts from western New York. Journal of Paleontology 65: 248–254.

Eriksson, M. 1999. Taxonomic discussion of the scolecodont genera Nereidavus Grinnell, 1877, and Protarabellites Stauffer, 1933 (Annelida: Polychaeta). Journal of Paleontology 73: 403-406.

Eriksson, M. and Bergman, C.F. 2003. Late Ordovician jawed polychaete faunas of the type Cincinnatian Region, U.S.A. Journal of Paleontology 77: 509-523.

Grinnell, G.B. 1877. Notice of a new genus of annelids from the Lower Silurian. American Journal of Science and Arts 14: 229–230.

Hints, O. and Eriksson, M.E. 2007. Diversification and biogeography of scolecodont-bearing polychaetes in the Ordovician. Palaeogeography, Palaeoclimatology, Palaeoecology 245: 95-114.

Kielan-Jaworowska, Z. 1962. New Ordovician genera of polychaete jaw apparatuses. Acta Palaeontologica Polonica 7: 291-325.

Wooster’s Fossil of the Week: A helpful echinoid from the Upper Cretaceous of Israel

April 27th, 2014

Echinoids a 042214These beaten-up fossils have served me well in the field this month. They are the regular echinoid Heterodiadema lybicum (Agassiz & Desor, 1846). They are common in the Cenomanian throughout northern Africa and the Middle East. These particular specimens, the other sides of which are shown below, are from the En Yorqe’am Formation we’ve been studying here on the rim of Makhtesh Ramon, southern Israel. When I find them in abundance I know I’m in the top half of that formation. They’ve previously been featured indirectly as a Fossil of the Week for the bites they made into the shells of oysters, producing the trace fossil Gnathichnus.
Echinoids b 042214The species Heterodiadema lybicum was named by Pierre Jean Édouard Desor (1811-1882) in 1846. We’ll meet him in a later entry. The genus Heterodiadema was erected in 1862 by Gustave Honoré Cotteau (1818-1894), who is pictured below. There is not much at all about Cotteau in the English literature, but with Google Translate I was able to sort out a bit of his story from the French. He was one of those glorious amateurs who make such important contributions to the science of paleontology. (I like the new term “citizen scientists” for this group, although I emphasize I’m a citizen too!) Cotteau was a judge in Auxerre, Burgundy, France. In his spare time he had a passion for living and fossil echinoids, eventually amassing a collection of over 500 species. He was also, as you might guess, a volunteer curator of the city museum in Auxerre. In 1889 he was President of the Société zoologique de France, a highly prestigious position. He was an important force in the early understanding of echinoderms.
Cotteau GustaveAgain, these specimen photos were taken under “field conditions” in Israel with a cleaner’s cloth for a background. As you read this, though, I am with luck back in my cozy home in Wooster.

References:

Agassiz, L. and Desor, P.J.E. 1846. Catalogue raisonné des familles, des genres, et des espèces de la classe des échinodermes. Annales des Sciences Naturelles, Troisième Série, Zoologie 6: 305-374.

Geys, J.F. 1980. Heterodiadema libycum (Agassiz & Desor, 1846), a hemicidaroid echinoid from the Campanian of Belgium.  Anales de la Societe geologique du Nord 99: 449-451.

Smith, A.B., Simmons, M.D. and Racey, A. 1990. Cenomanian echinoids, larger foraminifera and calcareous algae from the Natih Formation, central Oman Mountains. Cretaceous Research 11: 29-69.

Wooster’s Fossils of the Week: A scleractinian coral and its tube-dwelling symbionts (Middle Jurassic of Israel)

April 20th, 2014

MatmorCoral010114aI have a weakness for the beautiful scleractinian corals of the Matmor Formation (Middle Jurassic, Callovian-Oxfordian) of southern Israel. This particular specimen is Microsolena aff. M. sadeki from locality C/W-367 in Hamakhtesh Hagadol, southern Israel. (The “aff.” in the name means “affinities with”. It is a way of saying this looks like a particular species, but we’re not quite sure.) This is a place we’ve now had ten Wooster Team Israel expeditions, the latest of which was last summer. The corals are a prominent part of the very diverse fossil fauna there. Note in the above side view of the specimen the star-shaped corallites (which held individual polyps) each with radiating septa. In the middle of the view you can see a narrow tube covered by coral skeleton. (More on this below.)
MatmorCoral010114bThis is a top view of the coral. It has a generally flat base and an upper surface with extended knobs. Usually this particular species is flat across the top as well as the base, giving it a platter shape as in this previous Fossil of the Week.
MatmorCoral010114cFlip the coral over and we see how it is preserved. The skeleton was originally made of the mineral aragonite, which dissolved after the death and burial of the colony. The resulting void was filled with stable calcite, preserving even fine details of the septa (see below). This delicate preservation, though, is only of the exterior of the skeleton. The interior is coarsely crystalline calcite with no trace of internal coral structures. This preservation, then, is properly called a cast, not true replacement.
MatmorCoral010114tubeThese scleractinian corals had many symbionts (organisms that lived with them). Among them were tube-dwelling worms, probably polychaetes, that spread across the surface. We know this happened while the coral was alive because, as seen above, the septa sometimes grew over the tubes. The tubes themselves are here preserved in three dimensions because they are originally calcitic and did not dissolve after death and burial.

We have much to learn about these gorgeous Jurassic fossil corals of Israel. They are virtually unstudied and offer a great opportunity for comparing them to the global Jurassic coral world.

References:

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 366: 136-153.

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

Reolid, M., Molina, J.M., Löser, H., Navarro, V. and Ruiz-Ortiz, P.A. 2009. Coral biostromes of the Middle Jurassic from the Subbetic (Betic Cordillera, southern Spain): Facies, coral taxonomy, taphonomy, and palaeoecology. Facies 55: 575-593.

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: An unusual scleractinian coral from the Upper Cretaceous of Israel

April 13th, 2014

Aspidiscus 041114aOriginally this was going to be a mystery fossil for a crowd-sourced identification while I’m here in Israel doing fieldwork, but through the wonders of the internet I finally found a match for the strange fossil above: it is the scleractinian coral Aspidiscus König, 1825 (Family Latomeandridae) Yoav Avni and I found several specimens in the lower third of the En Yorqe’am Formation (Upper Cretaceous, Cenomanian) in the Negev of southern Israel. I had never seen anything like it before.

The view above is of the upper surface of this discoidal fossil. There are several short and seemingly random ridges, which I learned later are called monticules in this genus. Each monticule has a series of septa, or thin vertical partitions. This was a compound coral, meaning it had multiple polyps on its surface, presumably each sitting on a monticule.
Aspidiscus 041114bThis is a reverse view of the En Yorqe’am variety of Aspidiscus. The pits appear to be molds of a gastropod on which the young coral must have recruited. It then grew centripetally, making a fine series of growth lines across a soft sediment.
Aspidiscus cristatus diagramThis diagram from Pandey et al. (2011) is a diagram of Aspidiscus cristatus found in the Cenomanian of Sinai, not too far from here. (This species is also found in Algeria, Tunisia, Spain, Greece, and Afghanistan — all in the Cenomanian.) Note that the center of A. cristatus has two large crossing monticules and the Israeli specimen does not. This is why I’m keeping it in open nomenclature — it doesn’t appear to be the same species. A. cristatus is found in the middle to early late Cenomanian; the En Yorqe’am specimen seems so far to be only in the early Cenomanian. This may mean the Israeli version is an older species. Both clearly liked living in marly shallow marine sediments.
Aspidiscus symbiontsHere’s the bonus: look at the round holes in the upper surfaces of these two specimens. These are caused by symbionts of some kind that lived within the growing coral. You can see best in the specimen on the right how the coral grew around the symbionts, producing a kind of tube. Nice.

Sorry for the lower quality of images this week. I’m photographing the fossils as best I can with a bedside lamp, a tiny tripod, and a shirt for background.

References:

Avnimelech, M. 1947. A new species of Aspidiscus from the Middle Cretaceous of Sinai and remarks on this genus in general. Eclogae geologicae Helvetiae 40: 294-298.

Gill, G.A. and Lafuste, J.G. 1987. Structure, repartition et signification paleogeographique d’Aspidiscus, hexacoralliaire cenomanien de la Tethys. Bulletin de la Societe Geologique de France 3: 921-934.

Pandey, D.K., Fürsich, F.T., Gameil, M. and Ayoub-Hannaa, W.S. 2011. Aspidiscus cristatus (Lamarck) from the Cenomanian sediments of Wadi Quseib, east Sinai, Egypt. Journal of the Paleontological Society of India 56: 29-37.

Wooster’s Fossil of the Week: A brontothere jaw fragment (Miocene of South Dakota)

April 6th, 2014

Titanotherium proutiiThis fossil has been sitting in a glass case outside my office door for nearly three decades. Only this year — in the desire to find more Fossils of the Week — did I bother to open the cabinet and take it out for a looksie. On the reverse was a 19th century label: “Titanotherium proutii, Badlands, SD”. That started me on a complicated journey through the literature to see just what sort of creature bore these magnificent molars, as well as the history of its discovery.
Titanotherium proutii occlusalIn this occlusal (meaning the biting surface) view you can see in the beautiful flowing lines of the hard (dark) and softer (light) enamel that there are some serious cracks repaired with a dodgy yellowish glue. The specimen is very fragile — that glue has probably been holding it together for well over a century. These are classic plant-eating teeth for both cutting and grinding leaves, roots and small branches.
TitanotheriumThe animal represented here is a titanothere, a large extinct mammal common in what would become the Badlands of South Dakota during the Paleogene. Above is a recreation of a relative of our species: Megacerops (Titanotherium) robustum. (The artist who drew this illustration in 1912 was Robert Bruce Horsfall, 1869-1948.) The titanotheres, now better known as brontotheres, were roughly the size and shape of rhinoceroses, but were actually more closely related to horses. They had elephant-like feet, inwardly-curved skull caps, and impressive horns on the nose.

I usually delight in tracking down taxonomic histories (the technical history of scientific names), but Titanotherium proutii has defeated me. The history of this taxon is convoluted beyond recovery — a sad tale of mistakes, misplaced fossils, specimens given multiple names, and over-zealous “splitting” of taxa. In other words, typical middle 19th century vertebrate paleontology. Mader (1998) says that Titanotherium Leidy 1853 (or 1852?) is a nomen dubium or “doubtful name”. Even the species, which later became Palaeotherium proutii, is nomen dubium. The names are simply worthless to science. I have been unable to figure out what the accepted name for our fossil now is.
Joseph_LeidyJoseph Leidy (1823-1891) named Titanotherium and (maybe) T. proutii (there is dispute as to who named it first). Leidy was a well known American biologist and paleontologist who taught first at the University of Pennsylvania and then Swarthmore College. He described and named the first nearly-complete dinosaur skeleton, Hadrosaurus foulkii. (It was found in the Cretaceous of New Jersey and he named it in 1858.) Leidy was also an early supporter of Charles Darwin and his the new theory of evolution, early enough for this to be an unpopular position. Edward Drinker Cope was one of his students, which forever places him at the beginning of the famous “Bone Wars” between Cope and Othniel Charles Marsh, which raged from 1877 to 1892. That epic conflict actually began in the New Jersey marl pits where Leidy’s hadrosaur was found. Leidy thus leaves us with a mixed legacy of discoveries, innovations and insights mixed with errors and folly. Just the sort of character we would expect on the frontier of a new science in a new country.
Leidy1Leidy’s 1853 (Plate XVI) figure of a jaw fragment of “Titanotherium proutii“.

References:

Leidy, J. 1853. The ancient fauna of Nebraska: or, a description of remains of extinct Mammalia and Chelonia, from the Mauvaises Terres of Nebraska. Smithsonian contributions to knowledge, vol. 6. Washington, Smithsonian Institution.

Mader, B.J. 1998. Brontotheriidae. In: C.M. Janis, K.M. Scott, and L.L. Jacobs (eds.), Evolution of Tertiary Mammals of North America 1: 525-536.

Mihlbachler, M.C., Lucas, S.G. and Emry, R.J. 2004. The holotype specimen of Menodus giganteus, and the “insoluble” problem of Chadronian brontothere taxonomy. Paleogene Mammals. New Mexico Museum of Natural History and Science Bulletin 26: 129-135.

Warren, L. 1998. Joseph Leidy: the last man who knew everything. Yale University Press, New Haven; 303 pages.

Wooster’s Fossil of the Week: Thoroughly encrusted brachiopod from the Upper Ordovician of Indiana

March 30th, 2014

1 Rafinesquina ponderosa (Hall) ventralLast week was an intensely bored Upper Ordovician bryozoan, so it seems only fair to have a thoroughly encrusted Upper Ordovician brachiopod next. The above is, although you would hardly know it, the ventral valve exterior of a common strophomenid Rafinesquina ponderosa from the Whitewater Formation exposed just south of Richmond, Indiana (locality C/W-148). I collected it earlier this month on a trip with Coleman Fitch (’15).
2 Rafinesquina ponderosa (Hall) dorsalThis is the other side of the specimen. We are looking at the dorsal valve exterior. Enough of the brachiopod shows through the encrusters that we can identify it. Note that both valves are in place, so we say this brachiopod is articulated. Usually after death brachiopod valves become disarticulated, so the articulation here may indicate that the organism had been quickly buried. This brachiopod is concavo-convex, meaning that the exterior of the dorsal valve is concave and the exterior of the ventral valve is convex.
3 Protaraea 032314Returning to the ventral valve, this is a close-up of the encruster that takes up its entire exterior surface. It is the colonial heliolitid coral Protaraea richmondensis Foerste, 1909. (Note the species name and that it was collected just outside Richmond, Indiana.) This thin coral is a common encruster in the Upper Ordovician. Usually it is a smaller patch on a shell. This is the most developed I’ve seen the species. The holes, called corallites, held the individual polyps.
4 Bryo on Protaraea 032314The encrusting coral has an encruster on top of it. This is a trepostome bryozoan, which you can identify by the tiny little holes (zooecia) that held the individuals (zooids). The patch of coral it is occupying must have been dead when the bryozoan larva landed and began to bud.
5 Trepostome 032314Now we’re returning to the concave dorsal valve with its very different set of encrusters. This is a close-up of another kind of trepostome bryozoan, this one with protruding bumps called monticules. They may have functioned as “exhalant current chimneys”, meaning that they may have helped channel feeding currents away from the surface after they passed through the tentacular lophophores of the bryozoan zooids. For our purposes, this is a feature that distinguishes this bryozoan species from the one on the ventral valve.
6 Cuffeyella 032314There is a third, very different bryozoan on the dorsal valve. This blobby, ramifying form is a well-developed specimen of Cuffeyella arachnoidea (Hall, 1847). It is again a common encruster in the Upper Ordovician, but not usually so thick.
7 Cuffeyella on hinge 032314If we look closely at the hinge of the brachiopod on the dorsal side, we can see a much smaller C. arachnoidea spreading on the ventral valve.
8 Encrusted edge 032314Finally, this is a side view of the brachiopod with the ventral valve above and the dorsal valve below. We’re looking at the junction of the articulated valves, the commissure. For the entire extent of the commissure, the encrusting coral grows to the edge of the ventral valve and no further. This is a strong indication that the brachiopod was alive when the coral was growing on it. The brachiopod needed to keep that margin clear for its own feeding.

The paleoecological implications here are that the coral was alive at the same time as the brachiopod. This means that the convex exterior surface of the ventral valve was upwards for the living brachiopod. The concave exterior surface of the dorsal valve faced downwards. The coral and bryozoan encrusting the top of the living brachiopod were exposed to the open sea; the bryozoans encrusting the undersurface of the living brachiopod were encrusting a cryptic space. We are thus likely seeing the living relationships between the encrusters and the brachiopod — this encrustation took place during the life of the brachiopod.

Further, this demonstrates that this concavo-convex strophomenid brachiopod was living with the convex side up. This has been a controversy for decades in the rarefied world of brachiopod paleoecology. This tiny bit of evidence, combined with some thorough recent studies (see Dattilo et al., 2009; Plotnick et al., 2013), strengthens the case for a convex-up orientation. Back when I was a student these would be fighting words!

References:

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

Dattilo, B.F., Meyer, D.L., Dewing, K. and Gaynor, M.R. 2009. Escape traces associated with Rafinesquina alternata, an Upper Ordovician strophomenid brachiopod from the Cincinnati Arch Region. Palaios 24: 578-590.

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

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

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

Plotnick, R.E., Dattilo, B.F., Piquard, D., Bauer, J. and Corrie, J. 2013. The orientation of strophomenid brachiopods on soft substrates. Journal of Paleontology 87: 818-825.

Wooster’s Fossil of the Week: Intensely bored bryozoan from the Upper Ordovician of Kentucky

March 23rd, 2014

Bored Bryo 1 585Yes, yes, I’ve heard ALL the jokes about being bored, and even intensely bored. I learn to deal with it. This week we continue to highlight fossils collected during our productive expedition to the Upper Ordovician (Cincinnatian) of Indiana (with Coleman Fitch ’15) and Kentucky (with William Harrison ’15). Last week was Coleman’s turn; this week it is William’s.

The beautiful fan-like bifoliate (two-sided) trepostome bryozoan above was collected from the lower part of the Grant Lake Formation (“Bellevue Limestone”) at our locality C/W-152 along the Idlewild Bypass (KY-8) in Boone County, Kentucky (N 39.081120°, W 84.792434°). It is in the Maysvillian Stage and so below the Richmondian where Coleman is getting most of his specimens. I’ve labeled it to show: A, additional bryozoans encrusting this bryozoan; B, a very bored section; C, a less bored surface showing the original tiny zooecia, monticules, and a few larger borings.
Bored Bryo 2 585The other side of this bryozoan is more uniform. It has an even distribution of small borings and no encrusters. This likely means that at some point after the death of the bryozoan and subsequent bioerosion this side was placed down in the mud while the exposed opposite side was encrusted.
Encruster Bored Bryo 031314_585A closer view of the upwards-facing side (with the encrusting bryozoan at the top) shows just how intense the boring was prior to encrustation. Some of the borings are close to overlapping. The encrusting bryozoan has its own borings, but far fewer and significantly larger.
Close borings 031314_585In this close view of the downwards-facing side we see lots of the small borings. Some are star-shaped if they punched through the junction of multiple zooecia. Note that these borings are rather evenly spread and seem to have about the same external morphology and and erosion. Likely they were all produced about the same time. It must have been a crowded neighborhood when all those boring creatures were home.

The questions that are provoked by this specimen are: (1) Were there any borings produced while the host bryozoan was still alive? (We may find elements of bioclaustration with some holes); (2) Why are zones B and C in the top image so different in the amount of bioerosion? Could zone C have still been alive at the time and resisted most bioeroders? Maybe zone C was covered by sediment? (But the margin is very irregular); (3) Why are the later encrusting bryozoans (zone A) so much less bioeroded?; (4) How do we classify such tiny pits that are between microborings and macroborings in size? (Trypanites is becoming a very large category) (5) What kind of organism made so many small pits? Were they filter-feeders as we always say, or was something else going on? (Sectioning specimens like this may reveal some internal connections between the pits.)

William has plenty of fun work ahead of him!

References:

Boardman, R.S. and Utgaard, J. 1966. A revision of the Ordovician bryozoan genera Monticulipora, Peronopora, Heterotrypa, and Dekayia. Journal of Paleontology 40: 1082-1108

Bromley, R.G. 1972. On some ichnotaxa in hard substrates, with a redefinition of Trypanites Mägdefrau. Paläontologische Zeitschrift 46: 93–98.

Erickson, J.M. and Waugh, D.A. 2002. Colony morphologies and missed opportunities during the Cincinnatian (Late Ordovician) bryozoan radiation: examples from Heterotrypa frondosa and Monticulipora mammulata. Proceedings of the 12th International Conference of the International Bryozoology Association. Swets and Zeitlinger, Lisse; pp. 101-107..

Kobluk, D.R. and Nemcsok, S. 1982. The macroboring ichnofossil Trypanites in colonies of the Middle Ordovician bryozoan Prasopora: Population behaviour and reaction to environmental influences. Canadian Journal of Earth Sciences 19: 679-688.

Taylor, P.D. and Wilson. M.A. 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62 (1-2): 1–103.

Vogel, K. 1993. Bioeroders in fossil reefs. Facies 28: 109-113.

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

Wooster’s Fossil of the Week: Bryozoan bored and bryozoan boring in the Upper Ordovician of Indiana

March 16th, 2014

Bored Bryo on Brach top 585This week and next we will highlight fossils collected during our brief and successful expedition to the Upper Ordovician (Cincinnatian) of Indiana (with Coleman Fitch ’15) and Kentucky (with William Harrison ’15). We found what we needed to pursue some very specific topics.

Above is a trepostome bryozoan collected from the Liberty Formation (we should be calling it the Dillsboro Formation in Indiana; our locality C/W-149) on IN-101 in southeastern Indiana (N 39.48134°, W84.94843°). You can see the regular network of tiny little holes representing the zooecia (zooid-bearing tubes) of the calcitic zoarium (colony) of the bryozoan. The larger, irregular holes (still pretty small!) are borings cut by worm-like organisms into the bryozoan skeleton shortly after the death of the colony.
Bored Bryo on Brach bottom 585Flipping the specimen over we see the most interesting parts. On the left is a remnant of the original calcitic strophomenid brachiopod shell that was encrusted by the trepostome bryozoan. On the right the shell has broken away, exposing the encrusting surface of the trepostome. We are thus looking here at the inside of a brachiopod valve and the underside of the bryozoan that encrusted it.

This is just what we hoped to find for Coleman’s project on interpreting half-borings in brachiopod shell exteriors. This specimen demonstrates two crucial events after encrustation: First, the borings in the bryozoan extended down to the brachiopod shell and turned sideways to mine along the shell/bryozoan junction (note half-borings in the bryozoan base on the right), and second, the bryozoan broke mostly free of the brachiopod shell, with only a bit remaining on the left. Somewhere there is or was a fragment of that brachiopod with an exterior showing half-borings and no bryozoan encrustation. Thus a brachiopod without bryozoan encrusters may have actually been encrusted at some point, but the bryozoans were later detached. We’ve added a bit to the uncertainty of the encrusting fossil record — even calcitic skeletal evidence on this small scale can go missing. We’ve also started on a good story about the behavior of the tiny critters that bored into this shelly complex.
Ctenostome closer 031314_585A bonus in this specimen can be seen in this closer view of that brachiopod shell interior above. That branching network is a complex ctenostome bryozoan boring called Ropalonaria. This is a particularly well developed specimen with thicker, shorter zooids than I’ve seen before. This kind of boring is the subject of a previous Fossil of the Week entry.

Coleman has a great start on his Independent Study project with specimens like these. He has a lot of sectioning and adequate peeling ahead of him!

References:

Brett, C.E., Smrecak, T., Parsons-Hubbard, K. and Walker, S. 2012. Marine sclerobiofacies: Encrusting and endolithic communities on shells through time and space. In: Talent, J.A. (ed.) Earth and Life, International Year of Planet Earth, p. 129-157. Springer.

Pohowsky, R.A. 1978. The boring ctenostomate Bryozoa: taxonomy and paleobiology based on cavities in calcareous substrata. Bulletins of American Paleontology 73(301): 192 p.

Smrecak, T.A. and Brett, C.E. 2008. Discerning patterns in epibiont distribution across a Late Ordovician (Cincinnatian) depth gradient. Geological Society of America Abstracts with Programs 40:18.

Wilson, M.A., Dennison-Budak, C.W. 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 38:514.

Wooster’s Fossil of the Week: A whale ear bone (Neogene)

March 9th, 2014

Whale inner earbonesThis is another fossil that has sat in a display case for decades in Scovel before I really examined it. Unlike last week’s specimen, though, it has no identifying label on its reverse. This is always a serious disappointment for science — no location! I show the fossil above with a front and back view (as much as there is a front or back). We are looking at an auditory bulla (part of the middle ear system) of an ancient whale. The most we can say is that this may be from a type of sperm whale that lived during the Neogene. Likely this specimen was collected on the east coast of the United States, maybe Maryland or Virginia.

Surprisingly, whale ear bones are rather common in the later fossil record. They seem to have been of denser bone than the rest of the whale skeleton, so they were better preserved. The auditory bulla is a bony cover for the delicate middle ear bones and tissues. In humans it is part of our temporal bone. Whales have several adaptations in their ears for hearing underwater. They have no external ear opening. They use instead the lower jawbone to transmit vibrations to the ear complex (something like what many snakes do). They have a pad of fat to enhance these vibrations for the tiny ear bones (tiny relative to the massive size of the whale). You can learn much more about fossil whale ear bones at this excellent blog post from the Virginia Museum of Natural History.

You are asking, though, fine enough, but how can I use a fossil whale ear bone? There’s a video to train you! These bones have “ancient, ancient memory” that is “preserved sonically”. Just be sure to hold it in your non-dominant hand and remember that “this is an art”. Do it correctly and you will have tapped into the wisdom of our ancient whale brothers and sisters. To think that every day I walked blithely by this portal to the Knowledge of the Ages.

References:

Fraser, F.C. and Purves, P.E. 1960. Hearing in cetaceans: evolution of the accessory air sacs and the structure and function of the outer and middle ear in recent cetaceans. Bulletin of the British Museum (Natural History) 7: 1-140.

Ketten, D.R. 1997. Structure and function in whale ears. Bioacoustics 8: 103-135.

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