Another gorgeous day on the Yorkshire coast

June 10th, 2015

Dismantled pillbox Filey BeachSCARBOROUGH, ENGLAND (June 10, 2015) — We certainly can’t complain about the weather for our fieldwork in Yorkshire this year. Today was spectacular with blue skies and cool sea breezes. It made the long beach hikes very pleasant.

1 Mae on Speeton 061015This was our first day without our English colleague (and Yorkshire native) Paul Taylor, so we were on our own for transportation. We figured out the bus system, though, and made it to the Lower Cretaceous Speeton Clay at Reighton Sands in good time. Here is the last view you’ll have of Mae Kemsley (’16) working on her outcrops of this gray, mushy unit. We collected sediment samples this morning, along with a few last fossils.

2 Meredith on Speeton 061015Here is Meredith Mann (’16) doing the same. We finished all of our fieldwork for Mae’s project by 10:30 a.m., so we could make a long beach hike from the Speeton Cliffs northwards to Filey.

3 Meredith waiting on tide

4 Mae waiting on tideWe hiked as far as we could on Filey Brigg, but had to chill because our sites were still cut off by the high tide. Waiting for a tide to drop is tedious, but the students had plenty of patience.

5 Thalassinoides 061015We reached the large slabs of Hambleton Oolite Member (Upper Jurassic, Oxfordian) with Thalassinoides burrows to begin Meredith’s data collection. These are impressive trace fossils, with numerous shelly fossils in the surrounding matrix. We took reference photos and collected what we could. Unfortunately only three slabs met our criteria for measurements, so we moved to a unit exposed just below the Hambleton.

6 Cannonball concretionsOn the north side of Filey Brigg there are these large “cannonball” concretions, which were excellent stratigraphic markers for us. They are in the Saintoft Member of the Lower Calcareous Grit Formation. They told us that the units above were the Passage Beds Member of the Coralline Oolite Formation.

7 Passage Beds 061015Mae and Meredith are here collected fossils from the Passage Beds above the concretions. This unit is interesting to us because it contains shelly debris that was apparently washed onto shore during storms. These shells are often heavily encrusted with oysters and serpulids. Such sclerobionts have been little studied in this part of the section.

8 MMbus 061015On our sunny ride home the students sat in the front of the top section of our double-decker bus. Not a bad commute for a day’s work!

 

Team Yorkshire chooses projects

June 8th, 2015

5 Meredith on block 060815SCARBOROUGH, ENGLAND (June 8, 2015) — When we do field Independent Study projects in the Wooster Geology Department, we never know the exact topic until we’ve tested ideas on the actual outcrops. Today we did the last of our general exploration, and then at lunch Meredith Mann (’16) and Mae Kemsley (’16) decided on what they wanted to do for their projects. Meredith chose to study the fossil community associated with Thalassinoides trace fossils in the Birdsall Calcareous Grit Member of the Coralline Oolite Formation (Upper Jurassic, Oxfordian) at Filey Brigg. She’s shown above on one of the exposed bedding planes she will soon be examining in detail. Mae’s choice? You’ll read it here tomorrow.

1 Cayton Bay 060815We started our day in Cayton Bay, south of Scarborough. We had a long walk at high tide from our car south along the coast. After we hit the boulders in the middle of the view above, we saw no one else for the rest of the morning. The cliff is capped by Oxfordian limestones, with the thick Oxford Clay beneath. We had a few drops of rain while in Cayton Bay, but they didn’t develop into more than a sprinkle.

2 Kellaways rockWe couldn’t cross the boulder field (boulders and steep slopes are a theme of this expedition) until the tide receded a bit, so we spent some time examining this cliff exposure of the Osgodby Formation (Middle Jurassic, Callovian).

3 Gristhorpe BayWe crossed over Yons Nab (you just have to love these English place names) into Gristhorpe Bay to the south. Again, no other souls on this sunny day. After a quiet lunch, we retraced our route back to the car. The general reconnaissance is done. Time to start our work.

4 Filey Brigg 585 070815Back to Filey Brigg. This is a view down the axis of the Brigg as it enters the sea. Note what a spectacular day it is.

6 Meredith outcrop 060815Our job this afternoon was to work out the protocols of Meredith’s research, and pick her work sites. This is a beautiful exposure of the Birdsall Calcareous Grit Member on the north side of Filey Brigg. Note the Thalassinoides in place above Meredith. Meredith will be measuring and describing a section of the units here, and doing her mapping and collecting on the loose block along the Brigg itself.

Tomorrow we start Mae’s project!

Speeton Cliffs and Filey Brigg on a fine English summer day

June 7th, 2015

1 Speeton 060715SCARBOROUGH, ENGLAND (June 7, 2015) — This steep and muddy slope may not look like much, but it is the man exposure of the famous Speeton Clay, a Lower Cretaceous unit rich with fossils. Team Yorkshire started here (N 54.16654°, W 00.24567°) this morning to continue our reconnaissance of the local geology. The weather could not have been better. (I can only imagine what this sediment is like when wet!)

2 Slumped Speeton Pillbox 060715The Speeton Clay is quite mobile, with slips and land slippages very common along its coastal exposure. This is a World War II pillbox, part of the sea defenses of Britain, making its way down slope on the clay. On the shore itself are bits of previous WWII concrete installations that are now on the beach.

3 Red ChalkAfter collecting dozens of belemnites from the Speeton Clay for future research, we visited an exposure of the Red Chalk (Hunstanton Formation), which has smaller belemnites of a different genus.

4 Chalk cliffs s SpeetonIf we continued to the south we would have met these imposing cliffs of chalk, the northern part of the series of white coastal chalks that extends south past Dover. Seabirds swirled around them in the thousands this morning.

5 Paul marine tutorialWhile walking back to our car, Paul Taylor showed Meredith Mann and Mae Kemsley various intertidal organisms exposed on the broad beach beneath the Speeton Cliffs.

6 Barnacle covered boulder SpeetonAt a certain mid-tide level, the boulders on the beach were entirely covered with tiny barnacles. The rock itself is completely hidden.

7 Barnacles limpets SpeetonHere is a closer view of the rock surface. The oldest barnacles are greenish, the younger are gray. You can easily see several small limpets, but do you see the three large individuals in the center? They are camouflaged by their covering of barnacles.

8 Speeton cliffs beachFor a Sunday afternoon on such a nice day, we were pleased to see very few people on large stretches of the beach along the Speeton Cliffs. We had much more company later in the day.

9 Hambleton oolite south 060715In the afternoon we visited Filey Brigg for a look at parts of the Coralline Oolite Formation (Upper Jurassic, Oxfordian; N 54.21674°, W 00.26922°). We found the Hambleton Oolite Member very accessible and with a good number of fossils that could be collected. We are here looking at the “Upper Leaf” of the unit.

10 Thalassinoides sediment 060715Down on the Brigg itself we saw these massive overturned boulders of the Birdsall Calcareous Grit Member with spectacular examples of the trace fossil “boxwork” Thalassinoides. These fossil burrow systems were made by shrimp, probably of the callianassid variety.

11 Thalassinoides full relief 060715Sometimes the sediment between the infilled Thalassinoides tunnels was washed away, leaving this beautiful network in full relief.

12 Hambleton Oolite north 060715On the north side of Filey Brigg we could continue to follow the Upper Leaf of the Hambleton Oolite Member. The exposure is very good and well above the high tide. The access to this place, though, requires a low tide like we had this afternoon.

13 Hambleton Oolite Lower Leaf 060715At this site on the north side of Filey Brigg (N 54.21823°, W 00.26908°) we can get to the Lower Leaf of the Hambleton Oolite Member, with the Birdsall Calcareous Grit Member just above. Again, the Hambleton has many fossils that can be collected. If you look at the undersurface of the yellowish rock above our field party, you may be able to make out the Thalassinoides trace fossils. We can thus place the loose blocks with this distinctive trace fossil in their original stratigraphic position.

Another delightful field day. One more expedition tomorrow, and then we decide on the specific student projects.

 

Exploring the coast north of Scarborough

June 6th, 2015

Hundale Point section 060615SCARBOROUGH, ENGLAND (June 6, 2015) — Today Team Yorkshire got an early start this morning examining the Jurassic sections along the coast north of Scarborough. With Paul Taylor as our skilled English driver, we took the rental vehicle first to the village of Cloughton and then towards the coast for a hike to Hundale Point (above; N 54.33877°, W 00.42339°). There we exploring this beautiful section of the Scarborough Formation (Middle Jurassic, Bajocian) exposed as a cliff and wave-cut platform.

Bouldering 060615The day did not start easy. Our first attempt to get to the Point involved a long scramble over boulders at the bottom of the seacliffs. This is not my favorite kind of hiking as every step involves a decision about the stability and slipperiness of the next boulder. Note the slimy green algae on some surfaces. This was, though, a good introduction to various sedimentary features in the nonmarine portions of the Middle Jurassic section here. These rocks are important because they host petroleum under the North Sea.

Meredith Mae Hundale 060615Here we found one member of the Scarborough, the Spindle Thorn Limestone, to have lots of shelly fossils, including bivalves, gastropods, brachiopods, serpulids, belemnites and crinoids. They are relatively easy to extract from the matrix.

Hundale traces 060615Below the Spindle Thorn Limestone Member is the Hundale Sandstone Member. It has a fantastic suite of trace fossils exposed on the surface of the wave-cut platform. Here we see Thalassinoides (the large branching trace) and Planolites (unbranching smaller cylinders).

Hundale limpetsA great thing about working on a rocky seacoast is that a living hard substrate fauna is easily visible. Here’s a fun set of limpets and tiny barnacles at Hundale Point.

Robin Hood BayOur lunch stop was at Robin Hood’s Bay (N 54.41782°, W 00.52501°), which we accessed by way of Stoupe Beck. We briefly explored the Redcar Mudstone Formation (Lower Jurassic, Hettangian) on a rocky platform at low tide. Near the cliff we saw some trace fossils and a few lonely shelly fossils.

Whitby ammoniteWe ended our geological explorations of the day at Whitby, where we again examined a rocky wave-cut platform. We found numerous ammonites (like the one above), belemnites, and nuculid bivalves in the Whitby Mudstone Formation (Lower Jurassic, Toarcian). After our work on this very, very windy day, we headed into Whitby for ice creams and a look around the sites.

Whitby abbeyThe ruins of the Whitby Abbey are iconic for the region. They are high on a hill overlooking the city and the sea. This has been a set of ruins since the time of Henry VIII.

Hilda ammonites WhitbyPaul took us to a monument to local saints, including Saint Hilda (614-680), shown above. She was said to have turned the region’s snakes to stone, which you can see above at her feet. Those snakes better look very familiar to you!

Snake ammoniteTo enhance the ammonites-as-petrified-snakes legend, 19th Century craftsmen often carved snake heads onto ammonites. This specimen is in the Whitby Museum.

We learned a lot today. Paul even got to see a section new to him, the one at Hundale Point. Mae and Meredith have seen some project possibilities. Tomorrow we visit sections south of Scarborough. Note from our photos that we had sunny skies. The winds, though, were fierce!

 

Wooster’s Fossil of the Week: A Jurassic coral with beekite preservation from southern Israel

May 8th, 2015

MicrosolenaCW366_585This week’s fossil is again in honor of Annette Hilton (’17), now retired as my Sophomore Research Assistant this year. She has been assessing with great skill a large and diverse collection of scleractinian corals from the Matmor Formation in Hamakhtesh Hagadol in the Negev Desert of southern Israel. These specimens were collected during paleoecological studies by the Wooster paleontology lab and our Israeli colleagues. Above is a fantastic specimen of Microsolena Lamouroux 1821. We are looking at the top of a gumdrop-shaped corallum, with the corallites (which held the polyps) as shallow pits with radiating septa.
MicrosolenaReverseBeekiteCW366_585This is the reverse view of the coral, showing its concentric growth lines. The jumble in the center is shelly debris on which the coral originally established itself on the muddy seafloor. Note that the preservation here includes numerous little circles. These are centers of silica replacement called beekite rings (a form of chalcedony).
BeekiteMicrosolenaReverseCW366_585Above is a closer view of the beekite preservation. The silica circles have concentric rings of their own. This kind of preservation (a type of silicification) is common in the Matmor Formation. Corals like this one started as aragonitic skeletons and then were replaced by calcite and silica. I suspect the calcitization took place first because of the fine degree of preservation for most of the corallum.
Henry Beeke (1751–1837)So how do we get a term like beekite? Meet Rev. Henry Beeke (1751-1837), a rather unlikely scholar to make it to this blog. Beeke was an Oxford graduate in divinity, with a strong concentration in history. He became a prestigious Regius Professor of Modern History at Oxford. He was sought after as an expert of economics and taxation at the beginning of the 19th Century. As with many divines of the time, Beeke also pursued natural history, specializing in botany. At some point in his career he was noted as having described what we now call beekite, but I can’t find where in the literature. All I have is a brief mention of “Beekite, a new mineral, named after Dr. Beeke, at the Corbors” in Blewitt (1832, p. 15). Henry Beeke had the distinction of seeing this mineral variety named after him during his lifetime, which is rare in science.

References:

Blewitt, O. 1832. The panorama of Torquay: a descriptive and historical sketch of the district comprised between the Dart and Teign. Second edition. London: Simpkin and Marshall, 289 pages.

Church, A.H. 1862. XV. On the composition, structure, and formation of Beekite. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 23(152): 95-103.

Nose, M. and Leinfelder, R. 1997. Upper Jurassic coral communities within siliciclastic settings (Lusitanian Basin, Portugal): implications for symbiotic and nutrient strategies. Proceedings of the 8th International Coral Reef Symposium 2: 1755-1760.

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

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

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

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: How to make brilliant acetate peels, with a Jurassic coral example

May 1st, 2015

1_Image_1986My retiring Sophomore Research student, Annette Hilton (’17), is excellent at making acetate peels. These peels, like the one above she made from a mysterious Callovian (Middle Jurassic) coral, show fine internal details of calcareous fossils and rocks.

2_Image_1987This is a closer view of the acetate peel of the coral showing incredible detail in the radiating septa and connecting dissepiments. This is a solitary coral from the Matmor Formation of southern Israel. We thought we knew what it was until we examined this peel and saw features we can’t match with any coral taxa. (Experts are invited to tell us what it is!) This view looks like it is from a thin-section, but it is all acetate and was made in about 20 minutes.

An acetate peel is a replica of a polished and etched surface of a carbonate rock or fossil mounted between glass slides for microscopic examination. Peels cannot give the mineralogical and crystallographic information that a thin-section can, but they are faster and easier to make. For most carbonate rocks most of the information you need for a petrographic analysis can be recovered from an acetate peel. In many paleontological applications, an acetate peel is preferred to a thin-section because you get essentially two dimensions without sometimes confusing depth.

To make a peel you need the following:

A trim saw for rock cutting.
A grinding wheel with diamond embedded disks (with 45µm and 30µm plates)
Grinding grit (3.0 µm) in a water slurry on a glass plate.
Acetate paper.
A supply of 5% hydrochloric acid in a small dish.
A supply of water in another small dish.
A squeeze bottle of acetone.
Glass biology slides (one by three inches)
Transparent tape.
Scissors
A carbonate rock or fossil

We’re now going to show you how we make peels. This process was worked out by my friend Tim Palmer and me back in the 1980s. See the reference at the end of this entry.

DSC_5123Annette is in her required safety gear about to start the process by cutting a fossil. She needs to cut a flat surface that is usually perpendicular to bedding in a carbonate rock, or through a fossil at some interesting angle.

DSC_5124The specimen approaches the spinning diamond-embedded blade of the rock saw. Annette is holding the rock sample steady on a carriage she is pushing towards the blade. It is important to hold the specimen still as the blade cuts through it.

DSC_5126My camera is faster than I thought. Not only do you see those suspended drops of water, the spray is frozen in the air! The cut is almost complete.

DSC_5128Now we use a diamond-embedded grinding wheel (45 µm or 30 µm) to polish the surface cut with the saw. This will be the side from which we make the acetate peel.

DSC_5129A closer view of the rock (which contains an embedded bryozoan, by the way) being polished flat on the spinning wheel.

DSC_5130The best peels are made from surfaces that have the finest polish. We are using a 3.0 µm grit-water slurry on a glass plate to again polish the rock surface as smooth as possible, removing all saw and grinding marks.

DSC_5133Keep the plate wet and push down hard to polish the cut surface in the grit slurry. With carbonate rocks and fossils it takes no more than five minutes here to get an excellent polish.

DSC_5134Wash the specimen thoroughly in water to remove all grit. Check the polished surface for grinding marks. If you see any, return to the glass plate and slurry for more polishing.

DSC_5135We’re ready for the simple etching process. We use a Petri dish half-filled with 5% hydrochloric acid and a another dish with water. (Yes, I have a dirty hood in my lab.)

DSC_5136Annette is suspending the polished surface of the specimen downward into the acid bath. She dips it in only a couple millimeters or so. The acid reacts with the carbonate and fizzes. Her fingers are safely above the action, but if you’re nervous you can use tongs to hold the specimen. We usually keep the specimen in the acid for about 15 seconds, and then quench it with the water in the second dish. The etching time will vary with the strength of the acid and carbonate content of the specimen.

DSC_5140This is the kit you need to make the acetate peel itself. Note that we use a thin acetate rather than the thick sheets preferred by others.

DSC_5143The tricky part. When the specimen is dry, cut a piece of acetate somewhat larger than the etched surface. We then hold this acetate and the specimen in one hand, and the squeeze bottle of acetone in the other. The next step is to flood the etched surface, which is held flat and upwards, with the acetone and quickly place the acetate on the wetted surface. The acetate will adhere fast, so smooth it out with your fingers across the etched surface. At this point the acetone is partially dissolving the acetate, causing it to flow into the tiny nooks and crannies of the etched surface. The acetone evaporates and the acetate hardens into this microtopography.

DSC_5145If you did it correctly, you now have a sheet of acetate adhering entirely to the etched surface. With practice you learn how to avoid bubbles between the acetate and specimen. Opinions vary and how long to let the system thoroughly dry. We found that we can proceed to the next step in about five minutes.

DSC_5147Now you peel! Slowly and firmly pull the acetate off the specimen.

DSC_5152Carefully trim the acetate with scissors. Place this peel between two glass slides, squeeze tight, and seal the assemblage like a sandwich with transparent tape. You have now made an acetate peel. Easy!

DSC_5153Here’s our finished product. Twenty minutes from rock saw to peel. You’ll have to wait until another blog post to see what this particular peel shows us!

Reference:

Wilson, M.A. and Palmer, T.J. 1989. Preparation of acetate peels. In: Feldmann, R.M., Chapman, R.E. and Hannibal, J.T. (eds.), Paleotechniques. The Paleontological Society Special Publication 4: 142-145. [The link is to a PDF.]

 

Wooster’s Fossil of the Week: A twisted scleractinian coral from the Middle Jurassic of southern Israel

April 24th, 2015

1 Epistreptophyllum Matmor CW366 585Another exquisite little coral this week from the collection of Matmor Formation (Middle Jurassic, southern Israel) corals Annette Hilton (’17) and I are working through. We believe this is Epistreptophyllum Milaschewitsch, 1876. It is a solitary (although more on that in a moment) scleractinian coral found in marly sediments at our location C/W-366 in Hamakhtesh Hagadol. I’m always impressed at how well preserved these corals are considering their original aragonitic skeletons were replaced long ago.
2 Epistreptophyllum lateral bentOne cool thing about this specimen is the near 90° bend it took during growth. Apparently it was toppled over midway through its development but survived and grew a twist so it could keep its oral surface (where the polyp resided) upwards. Another interesting observation is the small bud visible near the base. Gill (1982) suggested that the solitary Epistreptophyllum in the Jurassic of Israel may have been able to branch into separate individuals. Pandey and Lathuilière (1997) doubted this and suggested that Gill had misidentified his Israeli specimens. Maybe so, but we’re pretty sure we have Epistreptophyllum here, and we definitely have budding. We’re always open to other ideas!
3 Epistreptophyllum orientedHere is another view of the specimen in its living position after the fall. I love the sweep of the vertical ribs as it made the bend.
4 Epistreptophyllum septaTo complete the tour of this specimen, here’s a view of the oral surface where the polyp lived. The radiating lines are the septa that extended vertically through the interior of the corallite.
5 Milaschewitsch plate 50Epistreptophyllum was named in 1876 by Constantin Milaschewitsch. Here is Plate 50 from that massive work. Epistreptophyllum is marked by the red rectangles. (Note the misspelling of the genus in the caption for figure 2.) I wish I knew more about Mr. Milaschewitsch, but his particulars are thus far not available. I can tell he worked in Moscow and St. Petersburg, Russia, but that’s all. If anyone knows more about this man, please add your information in the comments.

References:

Gill, G.A. 1982. Epistreptophyllum (Hexacorallaire Jurassique), genre colonialou solitaire? Examen d’un matériel nouveau d’Israel. Geobios 15: 217-223.

Milaschewitsch, C. 1876. Die Korallen der Nattheimer Schichten. Palaeontographica 21: 205-244.

Pandey, D.K. and Lathuilière, B. 1997. Variability in Epistreptophyllum from the Middle Jurassic of Kachchh, western India: an open question for the taxonomy of Mesozoic scleractinian corals. Journal of Paleontology 71: 564-577.

Wooster’s Fossil of the Week: A Middle Jurassic trace fossil from southwestern Utah

April 17th, 2015

1 Gyrochorte 2 CarmelTime for a trace fossil! This is one of my favorite ichnogenera (the trace fossil equivalent of a biological genus). It is Gyrochorte Heer, 1865, from the Middle Jurassic (Bathonian) Carmel Formation of southwestern Utah (near Gunlock; locality C/W-142). It was collected on an Independent Study field trip a long, long time ago with Steve Smail. We are looking at a convex epirelief, meaning the trace is convex to our view (positive) on the top bedding plane. This is how Gyrochorte is usually recognized.
2 Gyroxhorte hyporelief 585A quick confirmation that we are looking at Gyrochorte is provided by turning the specimen over and looking at the bottom of the bed, the hyporelief. We see above a simple double track in concave (negative) hyporelief. Gyrochorte typically penetrates deep in the sediment, generating a trace that penetrates through several layers.
3 Gyrochorte Carmel 040515Gyrochorte is bilobed (two rows of impressions). When the burrowing animal took a hard turn, as above, the impressions separate and show feathery distal ends.
4 Gyrochorte 585Gyrochorte traces can become complex intertwined, and their detailed features can change along the same trace.
5 Gibert Benner fig 1This is a model of Gyrochorte presented by Gibert and Benner (2002, fig. 1). A is a three-dimensional view of the trace, with the top of the bed at the top; B is the morphology of an individual layer; C is the typical preservation of Gyrochorte.

Our Gyrochorte is common in the oobiosparites and grainstones of the Carmel Formation (mostly in Member D). The paleoenvironment here appears to have been shallow ramp shoal and lagoonal. Other trace fossils in these units include Nereites, Asteriacites, Chondrites, Palaeophycus, Monocraterion and Teichichnus.

So what kind of animal produced Gyrochorte? There is no simple answer. The animal burrowed obliquely in a series of small steps. Most researchers attribute this to a deposit-feeder searching through sediments rather poor in organic material. It may have been some kind of annelid worm (always the easiest answer!) or an amphipod-like arthropod. There is no trace like it being produced today.

We have renewed interest in Gyrochorte because a team of Wooster Geologists is going to Scarborough, England, this summer to work in Jurassic sections. One well-known trace fossil there is Gyrochorte (see Powell, 1992).
6 Heer from ScienceOswald Heer (1809-1883) named Gyrochorte in 1865. He was a Swiss naturalist with very diverse interests, from insects to plants to the developing science of trace fossils. Heer was a very productive professor of botany at the University of Zürich. In paleobotany alone he described over 1600 new species. One of his contributions was the observation that the Arctic was not always as cold as it is now and was likely an evolutionary center for the radiation of many European organisms.

References:

Gibert, J.M. de and Benner, J.S. 2002. The trace fossil Gyrochorte: ethology and paleoecology. Revista Espanola de paleontologia 17: 1-12.

Heer, O. 1864-1865. Die Urwelt der Schweiz. 1st edition, Zurich. 622 pp.

Heinberg, C. 1973. The internal structure of the trace fossils Gyrochorte and Curvolithus. Lethaia 6: 227-238.

Karaszewski, W. 1974. Rhizocorallium, Gyrochorte and other trace fossils from the Middle Jurassic of the Inowlódz Region, Middle Poland. Bulletin of the Polish Academy of Sciences 21: 199-204.

Powell, J.H. 1992. Gyrochorte burrows from the Scarborough Formation (Middle Jurassic) of the Cleveland Basin, and their sedimentological setting. Proceedings of the Yorkshire Geological Society 49: 41-47.

Wilson. M.A. 1997. Trace fossils, hardgrounds and ostreoliths in the Carmel Formation (Middle Jurassic) of southwestern Utah. In: Link, P.K. and Kowallis, B.J. (eds.), Mesozoic to Recent Geology of Utah. Brigham Young University Geology Studies 42, part II, p. 6-9.

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

April 3rd, 2015

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

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

References:

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

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

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

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

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

March 27th, 2015

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

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

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

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

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

References:

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

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

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

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

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

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

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

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

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