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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.

Ordovician bioclaustration project begins

March 10th, 2014

Bellevue outcrop 031014FLORENCE, KENTUCKY–Today it was William Harrison’s turn to collect specimens for his Independent Study project. He’ll be working a full year on what he’s putting in these bags before he turns in his thesis. William’s project is an interpretation of the processes that led to bioclaustration pits in Upper Ordovician bryozoans, along with larger questions of bioerosion of trepostome bryozoans. We found some gorgeous specimens at the outcrop above.

William is collecting from what used to be called the Bellevue Limestone, a Maysvillian unit between the Fairmount and Corryville Formations. Now it is best known as the lower part of the Grant Lake Formation. The rocks represent shallow water deposits, much like the Whitewater Formation Coleman was working in yesterday, so it is loaded with eroded and encrusted brachiopods and bryozoans. This is Locality C/W-152 in our system along the Idlewild Bypass (KY-8) in Boone County, Kentucky (N 39.081120°, W 84.792434°).

William 031014William was particularly adept at finding large bryozoan zoaria (colonies), most of which were riddled with borings. He is here holding a specimen that in life would have been erect on the sea floor like a fan with feeding zooids on each side. You may be able to make out the many little bumps or monticules on its surface.

Guess who our neighbor was during our exploration of this outcrop?

Creation Museum 031014Yes, the irony is deep. “Billions of dead things” indeed, Mr. Ham!

Later that day we collected a few bored and bioclaustrating bryozoans from an exposure of the Kope Formation at Orphanage Road to the east (N 39.02984°, W 84.54121°). We have plenty of specimens to keep both William and Coleman busy, and already some ideas for poster presentations.

Just to show the human effect of sampling and collecting, our first stop of the day was entirely unsuccessful. We visited one of my first localities, an exposure of the Kope Formation at the confluence of the Ohio River and Gunpowder Creek in Boone County, Kentucky (C/W-7; N 38.90428°, W 84.79779°). It was here in 1984 that my wife Gloria and I found hundreds of fantastic encrusted cobbles, many with gorgeous edrioasteroids and thick accumulations of bryozoans. These were for a very brief moment famous in the local collecting community. Within a few months they were all gone. William and I were there now 30 years later hoping a new cobble or two might have eroded out, but we found nothing. A future researcher would have no idea such cobbles were present, except for the one paper in the literature.

 

Ordovician bioerosion and encrustation project begins

March 9th, 2014

Coleman 030914RICHMOND, INDIANA–Meet Coleman Fitch (’15) standing on the iconic outcrop of the Whitewater Formation (Upper Ordovician) on Route 27 about a mile south of Richmond (C/W-148; N 39.78722°, W 84.90166° — which has a nice Google Maps street view). This was his first day of fieldwork for his study of the complex relationship between borings and encrusters on brachiopods and mollusks. Note that Coleman has manfully taken off one glove for fossil collection. Despite the sun, we were freezing for science. Later in the day we collected from a warmer exposure of the Liberty Formation (Locality C/W-149) on IN-101 (N 39.48134°, W84.94843°).

Our collecting was very successful today. We found numerous examples of “half-borings” on trepostome bryozoan attachment surfaces, and many other curious fossils showing an interplay of early diagenesis (especially aragonite dissolution and calcite precipitation) and biotic processes.

Richmond specimen 030914Above is an example of the fun and complex fossils at the Whitewater locality. What processes do you think this specimen represents?

Tomorrow I meet William Harrison (’15) in northern Kentucky to search for bored bryozoans and bioclaustrations. It promises to be much warmer down there!

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.

Wooster paleontologists begin a new field season

March 8th, 2014

Southgate 030814RICHMOND, INDIANA–This is the first day of what upper midwesterners hilariously call “spring break”, so it is time to get some students in the field. I can’t say this is the first Wooster geology fieldwork of the year because that crazy Greg Wiles lab was out on the ice in deepest January. I spent today in eastern Indiana exploring field sites for a new generation of Independent Study students. Tomorrow and Monday Coleman Fitch (’15) and William Harrison (’15) will be joining me to collect specimens for their I.S. projects on Cincinnatian (Upper Ordovician) fossils. We’ll highlight their work in the next couple of days.

Above is one of the best known fossil sites in southeastern Indiana. It is the Southgate Hill section (sometimes called the St. Leon roadcut) at N 39.33899°, W 84.95287°. Exposed here are (from bottom to top) the Oregonia, Waynesville, Liberty, Whitewater and Saluda units of the Cincinnatian Group. It is a rich site — and incredibly muddy today. I suppose I’ll take mud over ice. Note the blue sky. By the end of the day it was as gray as the rocks, making the search for tiny fossil details difficult. Tomorrow promises to be much sunnier. Brach Slab 030814The brachiopods at the Southgate exposure are incredibly abundant and well preserved. These are strophomenids. Crinoids Bryozoans 030814Bryozoans (the twiggy bits) and crinoids (the circular fossils with star-shaped central holes). Can’t go wrong with this combination. More tomorrow and Monday as Coleman and William get to work. Meanwhile I’m wondering how I managed to get a motel room right next to an active railway …

Wooster’s Fossil of the Week: An agate-replaced coral from the Oligocene-Miocene of Florida

March 2nd, 2014

DSC_3384_585I long thought of this beautiful specimen as more rock than fossil. It is a scleractinian coral that has had its outer skeleton replaced by the silicate material agate and its interior skeleton completely hollowed out. The result is a geode that happens to also be a fossil.
FLMNH_585Then during last month’s North American Paleontological Convention in Gainesville, Florida, I saw the above specimens on display in the Florida Museum of Natural History. These fossils were so striking that I decided to highlight our single example.
DSC_3388_585This is a view of the top surface of the Wooster specimen. In the upper left is an array of holes with crystals radiating away from them. These are remnants of the original corallites, and there is just enough information there for us to conclude the likely genus is Montastraea. This piece thus becomes an example of Florida’s official state stone. Here’s the official definition: “… a chalcedony pseudomorph after coral, appearing as limestone geodes lined with botryoidal agate or quartz crystals and drusy quartz fingers, indigenous to Florida.” Our specimen came from the Hawthorn Group of rocks near Tampa, Florida.
DSC_3393_585The outside of the fossil shows horizontal banding remaining from the original growth lines in the coral, which is another clue that this is Montastraea. The coral made its skeleton of aragonite around 30 million years ago. After death and burial, silica-rich groundwater began to replace the aragonite on the surface of the coral with what later became banded agate. The interior dissolved away into a hollow cavity.

The common name for this fossil is “agatized coral“, and it is a collector’s item. It is apparently Florida’s only native gemstone. Pretty cool that their state rock and gemstone is a fossil!

References:

Scott, T.M. 1990. The lithostratigraphy of the Hawthorn Group of peninsular Florida. World Phosphate Deposits 3: 325-336.

Wooster’s Fossil of the Week: An interlocking rugose and tabulate coral (Devonian of Michigan)

February 23rd, 2014

Hexagonaria percarinata colony viewThis beautifully polished fossil looks like half of an antique bowling ball. Normally I hate polished fossils because the external details have been erased, but in this case the smooth surface reveals details about the organisms and their relationship. We have here a large colonial rugose coral with a smaller tabulate coral embedded within it. The specimen is from the Devonian of Michigan. It may look familiar because it is a large “Petoskey Stone“, the state stone (not fossil!) of Michigan. The large rugose coral is Hexagonaria percarinata (Sloss, 1939).
Hexagonaria percarinata close view 585In this closer view you can see the multiple star-like corallites of this coral. Each corallite held a tentacular feeding polyp in life. The radiating lines are thin vertical sheets of skeleton called septa. The corallites in this type of coral shared common walls and nestled up against each other as close as possible. In the lower center of the image you can see a very small corallite that represents a newly-budded polyp inserting itself as the colony grew. If rugose corals were like modern corals (and they probably were), the polyps were little sessile benthic carnivores catching small passing organisms with a set of tentacles. They may also have had photosymbionts to provide oxygen and carbohydrates through photosynthesis.
Tabulate coral intergrown with HexagonariaIn the midst of the rugose coral is this irregular patch with another type of coral: a tabulate coral distinguished by numerous horizontal partitions in its corallites (and no septa). It was likely a favositid coral, sometimes called a “honeycomb coral”. It was clearly living in the rugosan skeleton and not pushed into it by later burial. Note, though, the ragged boundary between the two corals. The rugose coral has the worst of it with some corallites deeply eroded. What seems to have happened is that the rugose coral had an irregular opening in its corallum (colonial skeleton) after death and the tabulate grew within the space, eventually filling it. The tabulate likely stuck out far above the rugose perimeter, but the polishing shaved them down to the same level. This is thus not a symbiotic relationship but one that happened after the death of the rugose coral.
Stumm, Erwin C   copyThe rugose coral species, Hexagonaria percarinata, was named in 1939 by Laurence Sloss, a famous sedimentary geologist with an early start in paleontology, but it is best known through the research of Erwin Charles Stumm (1908-1969; pictured above). Stumm was at the end of his life a Professor of Geology and Mineralogy and the Curator of Paleozoic Invertebrates in the Museum of Paleontology at the University of Michigan. Stumm grew up in California and then moved east for his college (George Washington University, ’32) and graduate (PhD from Princeton in 1936) education. He taught geology at Oberlin College up the road for ten years, and then moved to Michigan to start as an Associate Curator and Assistant Professor. I knew his name because in 1967 he was President of the Paleontological Society. He is said to have been a dedicated teacher of undergraduates and effective graduate advisor. It is fitting that his name is connected to such a popular fossil as Hexagonaria percarinata.

References:

Sloss, L. 1939. Devonian rugose corals from the Traverse Beds of Michigan. Journal of Paleontology 13: 52-73.

Stumm, E.C. 1967. Growth stages in the Middle Devonian rugose coral species Hexagonaria anna (Whitfield) from the Traverse Group of Michigan. Contributions from the Museum of Paleontology, The University of Michigan 21(5): 105-108.

Stumm, E.C. 1970. Corals of the Traverse Group of Michigan Part 13, Hexagonaria. Contributions from the Museum of Paleontology, The University of Michigan 23(5): 81-91.

A visit to the Florida Museum of Natural History

February 17th, 2014

1 Steph Lizzie Ground Sloth 021714GAINESVILLE, FLORIDA — The 10th North American Paleontological Convention here is sponsored by the Florida Museum of Natural History. (The meeting is excellent, by the way, and very well organized. Congratulations to the paleontological team that put it together.) Since the public display halls of the museum are just across the street from the convention center, Steph Bosch (’14), Lizzie Reinthal (’14) and I gave it a visit. You can’t go wrong with a natural history museum, but this one was extra fun and informative.

The first section of the museum we explored was the Hall of Florida Fossils. For a state with what I thought was a limited set of rocky outcrops and geological units, the range of Florida fossils is extraordinary. They are displayed here from microfossils (shown as magnified models) to large mammal skeletons. Steph and Lizzie are shown above looking up at a gynormous ground sloth skeleton from the Pleistocene.

2 Lizzie Steph Shark 021714A star of the Florida fossil exhibit is a reconstructed set of jaws from the giant Neogene shark Carcharodon megalodon. It has hundreds of  original teeth in several rows. I’m sure this photo setting has been used thousands of times by now.

3 Rainforest Visual 021714My favorite part of the museum was the Butterfly Rainforest. It is a large screened enclosure with thousands of live butterflies, and several birds as well, with dozens of tropical plant species. I liked it so much I went through it twice. (The students were somewhat less enthusiastic.) Butterflies flitted about, often landing in sunny spots and displaying their brilliant colors and patterns. (Yes, this means colorful photographs follow!)

4 Morpho chrysalis 021714 585Just before you enter the enclosure there is a nursery for rearing butterflies, from caterpillar to chrysalis to newly-emerged adult. Above is a specimen of Morpho peleides (Common or Blue Morpho) still clinging to the husk of its chrysalis. Several siblings wait for their unveiling.

5 Morpho on guidebookAfter we entered the enclosure, I opened an outdoor guidebook to identify the butterflies. Maybe it was just chance, or maybe the attraction of the photograph, but a rather worn Morpho peleides landed right on its  species description.

6 Geometric butterfly 021714 585I could not identify the other butterflies I photographed, but that won’t stop me from showing a couple more images. I like the geometric patterns on the wings of this species.

7 Two butterflies 021714This divergent pair shared a patch of sunlight. If any reader happens to know the names of these butterflies, please add them to the comments and I’ll update this text. [Katherine Marenco kindly identified the orange butterfly above as a Gulf Fritillary (Agraulis vanillae).]

There is much more at the Florida Museum of Natural History than we could see in our brief time there. We highly recommend if you’re in Gainesville that you visit this wonderful, friendly, enriching complex.

 

Wooster Geologists at the North American Paleontological Convention in Florida

February 16th, 2014

Lizzie & Steph 021514GAINESVILLE, FLORIDA–Steph Bosch (’14), Lizzie Reinthal (’14) and I flew out of icy Ohio this weekend to attend the 10th North American Paleontological Convention in warm, sunny northern Florida. The students jointly presented the beautiful poster above on their Independent Study projects in the Matmor Formation (Middle Jurassic, Callovian) of southern Israel. It was very well received, especially with the addition of fantastic scanning electron microscope images of bryozoans produced by our colleague Paul Taylor at the Natural History Museum in London.

Crowd scene 021514Here’s a crowd scene from the first poster session at NAPC. If you look closely in the center, you’ll see two Wooster alumnae who are prominent paleontologists. Can’t swing a cat at a paleo meeting without hitting Wooster Geologists.

Hilton 021514This is a nondescript image of our hotel and convention center in Gainesville. I show it only to marvel in the blue, blue sky and perfect temperatures. We are on the University of Florida campus near the Florida Museum of Natural History. The paleontology staff at that museum is sponsoring this meeting — and they are doing an extraordinary job made more complex by the absence of about a third of the participants still snow-bound in the north. We escaped through a window of clear weather in Ohio.

Wooster’s Fossil of the Week: A tubeworm-encrusted parasitic gastropod (Silurian of Indiana)

February 16th, 2014

Platyostoma1_585Last week three Wooster geology students and I visited Ken Karns, an enthusiastic citizen scientist who has developed an extraordinary fossil collection in his home in Lancaster, Ohio. Ken is a man of prodigious energies and skills as he not only is an expert fossil collector and preparator, he also has a world-class curated collection of Ohio beetles! He was introduced to us by our friend Brian Bade, a man with similar enthusiasms and skills. The students were Steph Bosch (’14), Lizzie Reinthal (’14) and Ian Tulungen (’15). Our goals were to meet Ken, see his magnificent collection with Brian and other friends, and then focus on a project for Ian’s future Independent Study work. Success on all counts, and the specimen above is evidence. Ken was very generous in loaning this specimen to us along with several others for Ian’s work.

The above specimen is from the type section of the Waldron Shale Member (Silurian, Wenlockian, Homerian, about 430 million years old) of the Pleasant Mills Formation near St. Paul, south-central Indiana. Ken Karns collected and prepared it. It is a platyceratid snail of the genus Platyostoma Conrad 1842. It is probably of the species P. niagarense Hall 1852, but there is another species in the same unit (P. plebeium Hall 1876). I’m not quite sure of the differences between these species because platyceratids are notoriously variable. It is possible they are synonymous. Unlike most gastropods, platyceratids had calcite shells instead of aragonite, so they are very well preserved. For an excellent taxonomic review of the genus Platyostoma and its founder, Timothy Abbott Conrad, please see Tony Edger’s blog entry. (We’ve talked about Conrad in this blog as well.)
Platyostoma2_585In this different angle on the specimen you can see additional encrusters (sclerobionts) on the surface of the Platyostoma shell. In the lower right is a remnant of a sheet-like bryozoan, but the most prominent sclerobionts are the tubeworms Cornulites proprius Hall 1876. These encrusters interest us very much.
Cornulitids on Platyostoma_585In this closer view it is apparent that several of the cornulitids are aligned with their apertures pointing in the same way. This is a pattern we’ve seen on many of these snails. Platyostoma was a parasitic snail that lived attached to crinoids, which were abundant in the Waldron fauna. They lived high on the calyx of the crinoid firmly fixed to its skeleton. These cornulitids and other encrusters were thus living high off the substrate perched on the snails. They were filter-feeders like the crinoids, so they may have been feeding on some suspended food fraction missed by the crinoid arms, or they were competing for nutrients and added to the parasitic load on the poor crinoids. The cornulitids were further living on a living snail shell, from what we can tell, so they grew with a substrate slowly growing underneath them. This produces all sorts of delicious paleoecological questions to sort out!
Platyostoma long cornulitid_585Check out the size of this specimen of Cornulites proprius attached to another Platyostoma niagarense. Clearly these tubeworms could do very well under these conditions! This is the largest cornulitid I’ve seen.

Ken_Karns_preparatory_labHere is Ken Karns in his fossil preparation laboratory, which he assembled himself. The box with the armholes is for air-abrading specimens to remove matrix.

Display cases KenThis is one section of the display cases Ken has in his basement museum. Most of the specimens shown here are from the Waldron Shale.

Platyostoma collection displayedA closer view of a display of Platyostoma from the Waldron Shale. Note the many encrusters.

Lizzie Brian KenLizzie Reinthal, Brian Bade and Ken talk about fossil preparation with some Waldron material. The cases are full of curated specimens.

Encrusted crinoid rootsThere are so many treasures in Ken’s collections. I am fascinated by this little slab showing the holdfast of a crinoid with sheet-like bryozoans encrusting it. The bryozoans show that the roots were at least partially exposed at some point.

Thank you again to Brian Bade for arranging this trip, and Ken Karns for being such a fantastic host. We are looking forward to many Waldron projects in the future!

References:

Baumiller, T.K. 2003. Evaluating the interaction between platyceratid gastropods and crinoids: a cost–benefit approach. Palaeogeography, Palaeoclimatology, Palaeoecology 201: 199-209.

Baumiller, T.K. and Gahn, F.J. 2002. Fossil record of parasitism on marine invertebrates with special emphasis on the platyceratid-crinoid interaction. Paleontological Society Papers 8: 195-210.

Brett, C.E., Cramer, B.D., McLaughlin, P.I., Kleffner, M.A., Showers, W.J. and Thomka, J.R. 2012. Revised Telychian–Sheinwoodian (Silurian) stratigraphy of the Laurentian mid-continent: building uniform nomenclature along the Cincinnati Arch. Bulletin of Geosciences 87: 733–753.

Feldman, H.R. 1989. Taphonomic processes in the Waldron Shale, Silurian, southern Indiana. Palaios 4: 144-156.

Gahn, F.J. and Baumiller, T.K. 2006. Using platyceratid gastropod behaviour to test functional morphology. Historical Biology 18: 397-404.

Gahn, F.J., Fabian, A. and Baumiller, T.K. 2003. Additional evidence for the drilling behavior of Paleozoic gastropods. Acta Palaeontologica Polonica 48: 156-156.

Hall, J. 1881. Descriptions of the Species of Fossils Found in the Niagara Group at Waldron, Indiana. In: Indiana Department of Geology and Natural Resources, Eleventh Annual Report, p. 217-345. [PDF of the text downloadable here.]

Liddell, W.D. and Brett, C.E. (1982). Skeletal overgrowths among epizoans from the Silurian (Wenlockian) Waldron Shale. Paleobiology 8: 67-78.

Peters, S.E. and Bork, K.B. 1998. Secondary tiering on crinoids from the Waldron Shale (Silurian: Wenlockian) of Indiana. Journal of Paleontology 72: 887-894.

Sutton, M.D., Briggs, D.E.G., Siveter, D.J. and Siveter, D.J. 2006. Fossilized soft tissues in a Silurian platyceratid gastropod. Proceedings of the Royal Society B: Biological Science 273(1590): 1039-1044.

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

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