Wooster’s Fossils of the Week: Silicified chonetid brachiopods from the Permian of West Texas

July 11th, 2014

Dyoros planiextensus Cooper and Grant 1975 585Above are four valves of the chonetid brachiopod Dyoros planiextensus Cooper and Grant, 1975. They are preserved by silicification and were recovered from a block of the Road Canyon Formation (Roadian Stage of the Guadalupian Series of the Permian System) from the Glass Mountains of southwestern Texas. It is from the same unit and location as the rhynchonellid brachiopod presented two weeks ago in this blog. (Please see that entry for additional links and explanations of the preservation.)

It took me awhile to work out the systematics of this species, so I must show you in exquisite detail —

Phylum Brachiopoda
Class Strophomenata Williams et al., 1996
Order Productida Sarytcheva and Sokolskaya, 1959
Suborder Chonetidina Muir-Wood, 1955
Superfamily Chonetoidea Bronn, 1862
Family Rugosochonetidae Muir-Wood, 1962
Genus Dyoros Stehli 1954
Species Dyoros planiextensus Cooper and Grant, 1975

Like music!

The chonetid brachiopods (at the suborder level) can be extremely common in Permo-Carboniferous units. I’ve seen hillsides in southeastern Ohio that seemed coated with them as they eroded from the shales beneath. They were well adapted to living on soft sediments with their flat, thin shells. In life they had a series of small hollow spines extended from the hinge line (the straight parts of the shell where the valves articulated; top in the photos above) to help anchor them as juveniles and possibly serve as extensions of their sensory systems.

Just a short entry this week. If all proceeded by plan, I’m somewhere deep in China right now!

References:

Cooper, G.A. and Grant, R.E. 1975. Permian brachiopods of West Texas, III. Smithsonian Contributions to Paleobiology 19:795-1921.

Racheboeuf, P.R., Moore, T.E. and Blodgett, R.B. 2004. A new species of Dyoros (Brachiopoda; Chonetoidea) from Nevada (United States) and stratigraphic implications for the Pennsylvanian and Permian Antler Overlap assemblage. Geobios 37: 382-394.

Stehli, F.G. 1954. Lower Leonardian Brachiopoda of the Sierra Diablo. Bulletin of the American Museum of Natural History 105: 257-358.

Wooster’s Fossil of the Week: A barnacle and sponge symbiosis from the Middle Jurassic of Israel

July 4th, 2014

Barnacle boring bioclaustration 1

[Programing note: Wooster's Fossil of the Week is now being released on Fridays to correspond with the popular Fossil Friday on Twitter and other platforms.]

This week’s fossil is again from the Matmor Formation (Middle Jurassic, Callovian) of southern Israel. (What can I say? We have a lot of them!) We are looking above at a crinoid pluricolumnal (a section of the stem made of several columnals) almost completely encrusted by a calcareous sponge (the sheet-like form with tiny pores). A round oyster is attached to the sponge in the lower center. In the left half you see the items of our interest this week: ovoid holes produced by barnacles. This specimen was studied by Lizzie Reinthal (’14) as part of her Senior Independent Study on the taphonomy of the Matmor crinoids.
Barnacle boring bioclaustration 2These barnacle holes are interesting because we can see in this closer view that the sponge grew around them. There is thickened sponge wall at the margins of the holes, and the feature in the middle is a thick mound built around one of these holes. The barnacles in the holes and the sponge were living together. If they weren’t either the sponge would have overgrown the empty holes or the barnacle would have cut through the dead sponge skeleton. This is an example of symbiosis. It would be a facultative relationship because the sponge and barnacle did not need each other to survive; each does just fine without the other. It could be considered parasitic if the barnacles acquired nutrients the sponge would have ordinarily received, or vice versa.
Barnacle boring bioclaustration 3This third view is of the edge of the sponge skeleton as it partially overlaps the barnacle holes. Now we see the nature of the intergrowth. The barnacle holes are actually borings into the crinoid pluricolumnal below. They are the trace fossil called Rogerella, which we have seen before in this blog. The sponge grew along the crinoid substrate covering all sorts of small holes, cracks and crevices, but when it reached these borings living barnacles were still in them filter-feeding away with their filamentous legs. The sponge thus laid its skeleton right up to the hole edges, eventually surrounding them with their spongy matrix.

The holes are borings, a kind of trace fossil. The structure created when the sponge surrounds a living boring barnacle like this is more difficult to name. It is not technically a bioimmuration (see Taylor, 1990) because the barnacles were not passively subsumed within the sponge skeleton. It may be a bioclaustration (Palmer and Wilson, 1988) because the sponge adapted its skeleton to isolate and surround the barnacle. I think we can at least say these are trace fossils in the ethological (behavioral) group called Impedichnia (Tapanila, 2005) because the barnacles acted as impediments, or limiting factors, to the growth of the sponge.

I love these examples of symbiosis in the fossil record, and the interesting debates about their interpretations.

References:

Cónsole‐Gonella, C. and Marquillas, R.A. 2014. Bioclaustration trace fossils in epeiric shallow marine stromatolites: the Cretaceous‐Palaeogene Yacoraite Formation, northwestern Argentina. Lethaia 47: 107-119.

Palmer, T.J. and Wilson, M.A. 1988. Parasitism of Ordovician bryozoans and the origin of pseudoborings. Palaeontology 31: 939–949.

Tapanila, L. 2005. Palaeoecology and diversity of endosymbionts in Palaeozoic marine invertebrates: Trace fossil evidence. Lethaia 38: 89–99.

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

Vinn, O. and Mõtus, M.A. 2014. Symbiotic worms in biostromal stromatoporoids from the Ludfordian (Late Silurian) of Saaremaa, Estonia. GFF (in press).

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 silicified rhynchonellid brachiopod from the Permian of West Texas

June 22nd, 2014

Rhynchonellid crura Permian Texas 585Sometimes fossils can be more useful when broken than whole. Above is a much-abused rhynchonellid brachiopod from the Road Canyon Formation (Middle Permian, Roadian, about 270 million years old) found in the Glass Mountains of southwestern Texas. It is part of a set of silicified fossils we etched out of a block of limestone in the last century. The shell has been replaced with resistant silica, so it was easy to extract from the limestone matrix with a long bath in hydrochloric acid that dissolved the carbonate but left everything else. The fossils are like delicate little glass husks. We’ve featured them in this blog several times.

Update: Matt Clapham kindly corrected me in the comments, and it is worth repeating in the text: “It’s Stenoscisma. The large spoon-shaped projection is actually called a spondylium, formed from merged dental plates and it’s quite distinctive for the Stenoscismatidae. The crura are broken but still visible in your specimen; they are the little struts parallel to the narrowest part of the spondylium. There are five Stenoscisma species that appear common in the Road Canyon Formation and yours looks most similar to Stenoscisma triquetrum to me (weakly sulcate with ribs that are somewhat subtle but still extend near the beak).” I made a bonehead mistake labeling the spondylium incorreectly, hence the “c”. Here’s to the value of Twitter, blogging, and knowledgeable colleagues!
Rhynchonellid Permian Texas 585Here’s the dorsal side of the specimen for completion. The exterior is in poor shape.

I’d love to identify this specimen to at least the genus level [update: see above and the comments!], but there is not enough detail preserved, at least for my skill set. The Permian brachiopods of West Texas were famously studied by G. Arthur Cooper and Richard E. Grant in the 1960s and 1970s. The numbers of species are overwhelming in this ancient reef system, and almost all of them are preserved in this delicate way.

References:

Cooper, G.A., and Grant, R.E., 1964, New Permian stratigraphic units in Glass Mountains, West Texas. American Association of Petroleum Geologists Bulletin 48: 1581-1588.

Cooper, G.A., and Grant, R.E. 1966. Permian rock units in the Glass Mountains, West Texas, In: Contributions to stratigraphy, 1966: U.S. Geological Survey Bulletin 1244-E: E1-E9.

Cooper, G.A. and Grant, R.E. 1972. Permian brachiopods of West Texas, I. Smithsonian Contributions to Paleobiology 14: 1–228. [and five other volumes]

Olszewski, T.D. and Erwin, D.H. 2009. Change and stability in Permian brachiopod communities from western Texas. Palaios 24: 27-40.

Wooster’s Fossil of the Week: A geopetal structure in a boring from the Middle Jurassic of Israel

June 15th, 2014

Geopetal Structure 585We have a very simple trace and body fossil combination this week that provides a stratigraphic and structural geologic tool. Above is a bit of scleractinian coral from the Matmor Formation (Middle Jurassic, Callovian) of Makhtesh Gadol in southern Israel. The coral skeleton was originally made of aragonite. It has been since recrystallized into a coarse sparry calcite, so we can no longer see the internal skeletal details of the coral. In the middle of this polished cross-section is an elliptical hole. This is a boring made by a bivalve (the trace fossil Gastrochaenolites). Inside the boring you see a separate elliptical object: a cross-section of a bivalve shell. This could be the bivalve that made the boring or, more likely, a bivalve that later occupied the boring for a living refuge. This, then, is the trace fossil (Gastrochaenolites) and body fossil (the bivalve shell) juxtaposition.

That stratigraphic and structural interest is that the boring and the bivalve shell are partially filled with a yellow sediment. This sediment has gravitationally settled to the bottom of these cavities (at slightly different levels). These holes have thus acted as natural builders’ levels showing is which way was down and which was up at the time of deposition. We can tell without any clues from the recrystallized coral the “way up” before any later structural deformation (or in this case rolling around on the outcrop) changed the orientation of the coral. Pretty cool and simple, eh? The name for this feature is a geopetal structure. There are some faulted and folded sedimentary rock exposures in the world where we search diligently for these little clues to original orientation (see, for example, Klompmaker et al., 2013). Not all geopetal structures have fossil origins (i.e., Mozhen et al., 2010), but most do. A little gift from paleontology to its sister disciplines.

References:

Klompmaker, A.A., Ortiz, J.D. and Wells, N.A. 2013. How to explain a decapod crustacean diversity hotspot in a mid-Cretaceous coral reef. Palaeogeography, Palaeoclimatology, Palaeoecology 374: 256-273.
Mozhen, G., Chuanjiang, W., Guohui, Y., Xueqiang, S., Guohua, Z. and Xin, W. 2010. Features, origin and geological significance of geopetal structures in Carboniferous volcanic rocks in Niudong Block, Santanghu Basin. Marine Origin Petroleum Geology 3: 15.
Wieczorek, J. 1979. Geopetal structures as indicators of top and bottom. Annales de la Societé géologique de Pologne 49: 215-221.

Wooster’s Fossil of the Week: A fragment of an asteroid (the sea star kind) from the Upper Cretaceous of Israel

June 8th, 2014

zichor asteroid aboral 585This is not an important fossil — there is not enough preserved to put a name on it beyond Family Goniasteridae Forbes, 1841 (thanks, Dan Blake) — but it was a fun one to find. It also photographs well. This is a ray fragment of an asteroid (from the group commonly known as the sea stars or starfish) I picked up from the top meter of the Zichor Formation (Coniacian, Upper Cretaceous) in southern Israel (Locality C/W-051) on my field trip there in April 2014. We are looking at the aboral (or top) surface; below is the oral view.
zichor asteroid oral surface 585In this oral perspective you can see a group of tiny, jumbled plates running down the center. This is the ambulacrum, which in life had a row of tube feet extending out for locomotion and grasping prey.
asteroid 2004Above is a sea star held by my son Ted on Long Island, The Bahamas, back in 2004. You can see a bit of resemblance between this modern species and the Cretaceous fossil, mainly the  large knobby ossicles running down the periphery of the rays.

The asteroids have a poor fossil record, at least when compared to other echinoderms like crinoids and echinoids. It appears that all post-Paleozoic asteroids derive from a single ancestral group that squeaked through the Permian extinctions (Gale, 2013). There is a significant debate about the evolution of the asteroids (see Blake and Mah, 2014, for the latest). Unfortunately our little critter is not going to help much in its resolution.

Recently it has been discovered that some living asteroids have microlenses in their ossicles to provide a kind of all-surface photoreception ability. Gorzelak et al. (2014) have found evidence that some Cretaceous asteroids had similar photoreceptors. Maybe our fossil goniasterid fragment could yield this kind of secret property with closer examination.

References:

Blake, D.B. and Mah, C.L. 2014. Comments on “The phylogeny of post-Palaeozoic Asteroidea (Neoasteroidea, Echinodermata)” by AS Gale and perspectives on the systematics of the Asteroidea. Zootaxa 3779: 177-194.

Gale, A.S. 2011. The phylogeny of post-Paleozoic Asteroidea (Neoasteroidea, Echinodermata). Special Papers in Palaeontology 38, 112 pp.

Gale, A.S. 2013. Phylogeny of the Asteroidea, p. 3-14. In: Lawrence, J.M. (ed.), Starfish: Biology and Ecology of the Asteroidea. The Johns Hopkins University Press, Baltimore.

Gorzelak, P., Salamon, M.A., Lach, R., Loba, M. and Ferré, B. 2014. Microlens arrays in the complex visual system of Cretaceous echinoderms. Nature Communications 5, Article 3576, doi:10.1038/ncomms4576.

Loriol, P. de. 1908. Note sur quelques stellérides du Santonien d’Abou-Roach. Bulletin de l’Institut égyptien 2: 169-184.

Mah, C.L. and Blake, D.B. 2012. Global diversity and phylogeny of the Asteroidea (Echinodermata). PLOS ONE 7(4), e35644.

Wooster’s Fossil of the Week: My favorite part of a crinoid (Middle Jurassic of Israel)

June 1st, 2014

Apiocrinites negevensis proximale 585In April of this year I completed my 11th trip to southern Israel for fieldwork in the Mesozoic. My heart warmed every time I saw these robust plates of the crinoid Apiocrinities negevensis, which was reviewed in a previous blog post. They are thick disks of calcite with a heft and symmetry like exotic coins. They are easy to spot in the field because of their size and incised perfect star. They have been a critical part of our paleoecological and systematic studies of the Matmor Formation (Callovian, Middle Jurassic) in the Negev. Lizzie Reinthal (14) and Steph Bosch (14) know them particularly well!
negevensis proximales 1This part of the crinoid is called the proximale. It has a round base that articulates with the columnal below it in the stem, and its top has five facets that hold the basal plates of the calyx. It is thus the topmost columnal, specialized to serve as the integration between the articulated stem below and the complicated head above. The pentastellate (five-armed star, but you probably figured that out) impression is called the areola. In the very center is the open hole of the lumen, which goes from the head all the way down through the stem to the holdfast as an internal fluid-filled cavity.
Composite Miller Apiocrinites arrowedAbove are Miller’s (1821) original illustrations of Apiocrinites rotundus with the proximale shown by the red arrow. Note how thin this piece is compared to the equivalent from Apiocrinites negevensis. The significant thickness of the proximale is one of the distinguishing features of the Negev species.

I saw many more of these beautiful fossils in the field this year. We don’t need any more for our research, but they always indicate that other good fossils are nearby.

References:

Ausich, W.I. and Wilson, M.A. 2012. New Tethyan Apiocrinitidae (Crinoidea; Articulata) from the Jurassic of Israel. Journal of Paleontology 86: 1051-1055.

Miller, J.S. 1821. A natural history of the Crinoidea or lily-shaped animals, with observation on the genera Asterias, Euryale, Comatula, and Marsupites. Bryan & Co, Bristol, 150 pp.

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 fly in amber

May 25th, 2014

Fly in amber 012614A classic fossil this week. I wish I could say more about it. The specimen lost its label years ago, so I don’t know where it is from or its age (although a good guess is Neogene). I also can’t identify it with my skill set beyond “fly” (Order Diptera). Beautiful, though. The images were not easy to make. I used our photomicroscope and played with a combination of light from below (transmitted) and above (reflected). The polished amber fragment is about the size of a pea and the fly is near the middle of it.
Fly legs in amber 012614A closer view here of the legs. Each segment can be seen, along with their tiny spines. This seems to be a particularly long-legged fly.

Preservation in amber is a well known phenomenon. An insect like ours gets itself trapped in a drop of tree resin. The resin hardens into amber by losing much of its volatile content with heat over time. Polish the piece and you can peer inside and see the occasional treasures of three-dimensionally preserved organisms. Oddly enough, in most cases these fossils are hollow external molds with no internal tissues preserved. What we see is the outside of this cavity with pigments embedded in the amber. (This fly has gorgeous red eyes, for example.) Remember the Jurassic Park premise that dinosaur DNA had been recovered from blood in a mosquito’s belly preserved in Dominican amber? It just doesn’t happen. In fact, a recent study (Penney et al., 2013) showed that insect DNA doesn’t even survive in sub-fossil assemblages.

I know from experience that it is very easy to be fooled by fake amber. As a policy, I’ve learned to not buy it in an Estonian open market (just as an example!). After Jurassic Park appeared, the demand for amber shot up, especially if it had animals in it. Artificial amber, and amber made from shavings and fragments (“pressed amber”) flooded the market. Caveat emptor. I tested our piece and it passed.

For more images of insects in amber, please follow the link or just search “amber”.

References:

Penney, D. 2002. Paleoecology of Dominican amber preservation: spider (Araneae) inclusions demonstrate a bias for active, trunk-dwelling faunas. Paleobiology 28: 389-398.

Penney, D., Wadsworth, C., Fox, G., Kennedy, S.L., Preziosi, R.F. and Brown, T.A. 2013. Absence of ancient DNA in sub-fossil insect inclusions preserved in ‘Anthropocene’ Colombian copal. PloS one 8(9), e73150. DOI: 10.1371/journal.pone.0073150

Poinar Jr, G.O. 1993. Insects in amber. Annual Review of Entomology 38: 145-159.

Wooster’s Fossils of the Week: “Star-rock” crinoids from the Middle Jurassic of Utah

May 18th, 2014

Isocrinus_nicoleti_Encrinite_Mt_Carmel_585This little slab of crinoid stem fragments comes from the Co-op Creek Member of the Carmel Formation (Middle Jurassic) exposed in northwestern Kane County, Utah. I collected it with my friend Carol Tang as we explored a beautiful encrinite (a rock dominated by crinoid skeletal debris) exposed near Mount Carmel Junction. In 2000, Carol and her colleagues published a description and analysis of this unit and its characteristic crinoid, Isocrinus nicoleti (Desor, 1845). This piece sits on a shelf in my office because it is so ethereal with its star-shaped columnals (stem sections). In fact, the local people in the area collect pieces of the encrinite and sell them as “star rocks“. As I recall, some folks were rather territorial about the outcrops!

Isocrinus nicoleti is one of only three crinoid species known in the Jurassic of North America. (The others are I. wyomingensis and Seirocrinus subangularis.) Tang et al. (2000) showed that this species migrated into southwestern North America by moving southward through a very narrow seaway for thousands of kilometers. I. nicoleti had long stems and relatively small crowns, so it left us zillions of the columnals and very few calices. These washed into large subtidal dunes creating the cross-bedded encrinite.
Isocrinus asteriaThe genus Isocrinus is still alive, most notably in the deep waters around Barbados in the Caribbean. Above is a diagram of Isocrinus asteria originally published by Jean-Étienne Guettard in 1761. The long stem is star-shaped in cross-section.
Pierre Jean Edouard DesorThis gentleman is Professor Pierre Jean Édouard Desor (1811-1882), who named Isocrinus nicoleti in 1845. He is shown here 20 years later. Desor was a German-Swiss geologist who studied two very disparate subjects: glaciers and Jurassic echinoderms. He trained as a lawyer in Germany, but got caught up in the democratic German unity movement of 1832-1833 and had to flee to Paris. In 1837 he met Louis Agassiz and began to collaborate with him on a variety of projects paleontological and glaciological. He even had a trip to the United States where he helped survey the coast of Lake Superior. He took a position as professor of geology at the academy of Neuchâtel, Switzerland, in 1852, eventually retiring in genteel affluence. (This is not how these geological biographies usually end!)

References:

Ausich, W.I. 1997. Regional encrinites: a vanished lithofacies. In: Brett, C.E. and Baird, G.C. (eds.): Paleontological Events, p. 509-519. Columbia University Press, New York.

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.

Desor, É. 1845 Résumé de ses études sur les crinoides fossilies de la Suisse. Bulletin de la Societe Neuchateloise des Sciences Naturelles 1: 211-222.

Hall, R.L. 1991. Seirocrinus subangularis (Miller, 1821), a Pliensbachian (Lower Jurassic) crinoid from the Fernie Formation, Alberta, Canada. Journal of Paleontology 65: 300-307.

Peterson, F. 1994. Sand dunes, sabkhas, streams, and shallow seas: Jurassic paleogeography in the southern part of the western interior basin. In: Caputo, M.V., Peterson, J.A. and Franczyk, K.J. (eds.): Mesozoic Systems of the Rocky Mountain Region, USA, p. 233-272. Rocky Mountain Section-SEPM, Denver, Colorado.

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: 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.

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