Revisiting the Gironde Estuary for our last day of fieldwork in southwestern France

June 7th, 2017

La Barde, France — Today Paul Taylor, Macy Conrad (’18) and I had our last fieldwork in France for this expedition. We returned to sites along the eastern shore of the Gironde Estuary to study the Biron Formation (Campanian, Upper Cretaceous), thus completing our three-part stratigraphic survey along with the Barbezieux and Aubeterre Formations. Macy is seen above crouching at the Caillaud South locality.

This is a view of the Caillaud South cliff from the south. The camera can’t convey how very white the rocks are and still keep the rest of the image in a correct exposure. A salt marsh is in the foreground.

The Pycnodonte vesicularis oysters are common at the Caillaud south locality, but they are well cemented into the limestone matrix. We’re looking here at an articulated shell with the right valve on top. This would have been the oyster’s living position.

There is a normal fault exposed in the Caillaud. It is still Biron Formation in either block, but the facies are slightly different on one side from the other.

This part of the estuary was the site of a significant Gallo-Roman settlement.

We also revisited the north side of Caillaud, where again it is Biron Formation with about a meter of Barbezieux on top of the cliff. The structures to the left are fishing towers.

Bryozoans are abundant in this exposure. Here is a nice bryozoan colony, probably the cyclostome Meliceritites, according to Paul.

Talmont-sur-Gironde from the south. This tiny place receives half a million visitors a year. Note the tidal mudflat in the foreground. We were near low tide.

This is an aerial view of the village, courtesy of Wikipedia. It is nearly surrounded by the sea at high tide. The village was founded in 1284 by Edward I of England. In 1652 it was destroyed by the Spanish. I’m surprised it survived World War II.

I’ll end this post with a French wildflower of some type we saw today. It symbolizes the beautiful countryside we had the privilege to explore. Thank you again to Paul and Patricia Taylor for hosting us so elegantly. Paul was also a spectacular field driver on the small country roads, and his knowledge of the fossils and stratigraphy is astonishing.

We have one more day in southwestern France, and then Macy and I head back to Paris.

 

 

A day of rocks and churches in southwestern France

June 6th, 2017

La Barde, France — This is our second-to-last day in southwestern France on this research expedition. Macy Conrad (’18), Paul Taylor (Natural History Museum, London) and I are continuing our study of sclerobionts on Upper Cretaceous (Campanian) oysters. I know the images of us facing into yet another set of white rocks are getting dull, so we’ll get the field shots out of the way first! Above, Macy is looking at the Barbezieux Formation just outside the village of Bonnes, a locality new to us on this trip.

Our second stop was one we visited last week: the Barbezieux Formation exposed in a narrow lane (“Chemin”) in Aubeterre. Another successful day with the Cretaceous oysters and their associates.

We visited two notable churches during our journey today. This one in St. Aulaye is notable for its very old tower and preserved Romanesque facade.

The Medieval carvings around the entrance are delightful. This is a man and what is apparently his donkey.

The second church we visited as in Bourg-du-Bost. This is a Thirteenth-Century building mostly intact.

The interior is richly decorated, and had automated organ music playing as we entered. The lights also switched on and off in a pattern I didn’t catch.

This church is known for its 13th century frescoes still mostly in place with their original colors.

The ceiling of the sanctuary is magnificent. Much attention was given over the centuries to detailed ornamentation and preservation in this relatively small country church. It survived countless wars in this region, including the most devastating ones of the 20th century.

Location GPS Unit Position
Bonnes 171 Barbezieux N45° 14.735′ E0° 08.935′

Wooster Geologists get to work in southwestern France

June 4th, 2017

La Barde, France — After a day of almost solid rain, we woke up the next morning to brilliant weather in southwestern France. Macy, Paul and I drove to the small town of Archiac, where we collected a bag full of gorgeous specimens of the oyster Pycnodonte vesicularis from the Aubeterre Formation.

The oysters could be easily pulled from the marly matrix. Our goal was to collect as many specimens with fossil sclerobionts on them as we could. Sclerobionts are organisms that live in or on hard substrates, in this case it means borings and encrusters.

Thanks to Paul Taylor for this modification of the stratigraphic column from Platel (1999). The three formations we are collecting from are the Biron, Barbezieux, and Aubeterre, all in the Upper Campanian.

We also visited an outcrop of the Segonzac Formation near Segonzac itself so Paul could collect bryozoans. We were at the edge of a vineyard.

The view from our last outcrop was wonderful. Peaceful countryside. That’s our field car parked on the roadside.

Location GPS Unit Position
Archiac 166 Aubeterre N45° 31.413′ W0° 17.909′
Chez Allard 167 Segonzac N45° 37.040′ W0° 11.546′

A day of geology on the coast of southwestern France

June 2nd, 2017

La Barde, France — Today we traveled west to the Gironde Estuary on the southwest coast to continue our survey of Campanian fossils. It looks like we will be working on the sclerobionts found with the extensive Pycnodonte oyster beds. Macy is above examining one of the best exposures of these fossils at a roadcut above Plage des Nonnes.

Our first stop was a roadcut in Mortagne of the Segonzac Formation, the oldest of the Campanian units we’ve seen so far.

The next outcrop was of the Biron Formation at the southern side of Caillaud. It is flanked by a salt marsh, with more open ocean conditions farther along.

Macy stands here on the fossiliferous Biron Formation at Caillaud south.

Another place where the ocean would love to kill me.

The Caillaud north locality was very fossiliferous, including excellent cheilostome bryozoans like Onychocella above. Despite the diversity of fossils here, there aren’t enough encrusted and bored oysters for us.

The cliffs just south of Plage des Nonnes. Definitely a location to visit at low tide.

These are some of the abundant Pycnodonte oysters we saw in the roadcut above Plage des Nonnes. We will certainly return to this outcrop later.

Besides the research, there were of course many other sites of interest. I took several images of this salt marsh at Caillaud south, for example, to use in my Sedimentology & Stratigraphy course.

We found this large jellyfish at Plage des Nonnes. The thickness and rigidity of the “jelly” is amazing.

This is the Talmont church perched on an outcrop above the sea.

The Romanesque, intricately carved entrance to the Talmont church.

It was an excellent day of culture and geology in France!

Location GPS Unit Position
Mortagne 160 Segonzac – lower N45° 28.763′ W0° 47.496′
Cliff north of Mortagne 161 Segonzac – upper N45° 28.963′ W0° 47.943′
Caillaud south 162 Biron N45° 31.805′ W0° 53.629′
Caillaud north 163 Biron N45° 31.916′ W0° 54.206′
Plage des Nonnes 164 Aubeterre N45° 33.534′ W0° 57.895′
Roadcut above Plage des Nonnes 165 Aubeterre N45° 33.627′ W0° 57.894′

 

Wooster Geologists begin fieldwork in southwestern France

June 1st, 2017

LA BARDE, FRANCE–Macy Conrad and I began our paleontological fieldwork in what may be the most beautiful part of Europe: southwestern France. Our superb guide and colleague is Natural History Museum scientist Dr. Paul Taylor, a long-time friend who has a home in this region with his wife Patricia. Above is a view of our first location: Aubeterre-sur-Drone. Extraordinary. And note the weather!

French food is indeed all it is said to be. This was my lunch: Gallette au Thon. Simple, I know, but very good.

This is our first outcrop. Macy is standing at an exposure of the Biron Formation, a Cretaceous (Campanian) limestone full of fossils, especially Pycnodonte oysters. Many of these oysters are encrusted by bryozoans. This is the “Garage Esso” location, also known as Route D17, in Aubeterre. We are in the exploratory phase of the project — essentially sorting out projects.

The overlying Barbezieux Formation (also Campanian — all the units are Campanian today) has well-exposed Pycnodonte oyster banks. These are of particular interest to us, especially if they are bored or encrusted. This is the “Chemin” section in Aubeterre.

More Barbezieux Formation further up the lane.

Our third unit is the Aubeterre Formation, which dominates the top of the city. This is the “car park outcrop”. All of these rocks are cliff-forming white limestones with abundant fossils.

Paul knew a field near Le Maine Roy where fossils from the Maurens Formation are exposed. This did not sound like a productive site, but it was the best of the day. Above you see a pile of rocks marked by a stake. These are larger stones removed from the fields by farmers. (I was reminded of what many French farmers in the north continually extract from their soil: World War I artillery shells!)

The many fossils include numerous large rudistid clams. It is  hard to imagine these large cones as bivalves, but they are. Rudists go extinct at the end of the Cretaceous.

This is a view of the top of a rudist with its right (capping) valve intact. It has a beautiful mesh structure.

Our last stop of the day was a roadcut near Chalais exposing the Biron Formation. It had a great diversity of fossils, including echinoids, sponges, oysters, and ammonites. It did not have an abundance of sclerobionts, so it probably won’t be a site for us in the future.

In Aubeterre we visited two fantastic churches. The first was St. Jacques. Most of it had been destroyed in the 17th century religious wars, but the Romanesque facade remains. This is the main entrance.

The primary attraction of the remnants of St. Jacques is a set of Medieval carvings. They are extraordinarily detailed, depicted all sorts of mysterious fantastical animals and people.

The second church in Aubeterre is very geological. St. Johns is underground, being carved as a cavern from the Barbezieux Formation. Here is a view of the entrance to what remains.

Inside is a huge space in which the sanctuary is carved. This is one of the largest such underground structures known.

The centerpiece is this reliquary, designed to look like the structure over the tomb of Jesus in the Church of the Holy Sepulchre in Jerusalem. Again, all this is carved out of the limestone.

We are staying in the gorgeous French home of Paul and Patricia Taylor in La Barde. It is an 1820 converted farmhouse, both beautiful and comfortable. The River Dronne is just a few steps away. We’ll have more photos of this wonderful and peaceful place in later posts.

I’ll end this day’s post with a view of some peaceful French woods near a field site.

Location GPS Unit Position
Garage Esso, Route D17, Aubeterre 153 Biron N45° 16.212′ E0° 10.274′
Route D17, Aubeterre 154 Barbezieux N45° 16.127′ E0° 10.268′
Chemin, Aubeterre 155 Barbezieux N45° 16.088′ E0° 10.257′
50 m up lane, Aubeterre 156 Barbezieux N45° 16.115′ E0° 10.229′
Back Chateau entrance, Aubeterre 157 Aubeterre N45° 16.362′ E0° 10.262′
Car Park, Aubeterre 158 Aubeterre N45° 16.344′ E0° 10.176′
Le Maine Roy 159 Maurens N45° 19.383′ E0° 07.885′
Chalais roadcut 160 Biron N45° 16.642′ E0° 02.395′

 

A Wooster Geologist on the Somme Battlefield

May 30th, 2017

Amiens, France — I had two days between the bryozoan meeting in Vienna and the fieldwork in southwestern France, so I decided to visit the World War I battlefields in the Somme Valley of northern France. It was a somber experience of natural beauty, stark and effective memorial architecture, and one of the deepest historical tragedies. I had a similar journey in 2010 to my Grandfather Snuffer’s World War I battlefield in the Meuse-Argonne. Above is a view of the cemetery at the Australian National Memorial near Villers-Bretonneux.

There were two major battles between the Allies and the Germans in the Somme Valley. The first, between July 1 and November 18, 1916, was the largest in terms of soldiers involved and lost. There were more than a million casualties, about even on each side, during those four and a half months of battle. A large proportion of those losses occurred on the first day; indeed, the first few minutes. The results were a draw. The second Battle of the Somme took place August 21 through September 2, 1918, and was an overwhelming Allied victory. This brief blog post is about my impressions of the battlefields a century later, so please follow the links for the historical background.

Gravestones at the Australian National Memorial. These are primarily for Australian soldiers, but there were also stones for New Zealanders, South Africans, Britons, and Canadians.

Flanders poppies grow naturally in this region, and they are also used decoratively in cemeteries. See the famous poem by John McCrae: In Flanders Fields.

An emblem of the soldier’s unit is engraved at the top of each stone.

The memorial building has walls of Portland Limestone (Jurassic of southern England) listing the thousands of missing Australian soldiers in the first battle.

In a compounding irony, the Australian National Memorial buildings and gravestones were shot up in turn during a skirmish here between Allied soldiers and invading Germans in 1940.

This is the small Proyart German Cemetery from the 1918 battle. There are over 450 cemeteries from all the involved nationalities throughout the valley. This one is seldom visited but immaculately maintained. The town of Proyart saw much fighting from the beginning of the war to its end.

An unknown German soldier. There are tens of thousands of unknown graves on the battlefields, matched by long, long lists of the missing.

Lochnagar Crater is a massive hole produced by the explosion of a British mine under the German lines on July 1, 1916 — the first day of the first battle. The bedrock is Cretaceous chalk, which was easy to tunnel with simple tools except that it had to be done in silence. No pickaxes were allowed. The last part of the explosives tunnel was dug under the German trenches with bayonettes alone. It is said that one soldier would pry a flint from the wall as another caught it before it struck the floor. The mine explosion was at that time the largest man-made sound in history.

You’ve heard that French farmers still find live artillery shells in their fields? Here’s one of them. About 60 tons a year of WWI explosives are removed from the Somme battlefields. The one above was marked for disposal with a red plastic cup. Demolition teams drive through the countryside in armored ammunition disposal vehicles removing munitions.

The local farmers repurpose many WWI items. Here a modern barbed wire fence is constructed with German barbed wire stakes from the war.

The Battle of Thiepval Ridge was a complicated and bloody operation in September, 1916. The ridge which cost so many Allied lives was selected as the site of the Anglo-French Memorial to the Missing of the Somme. Over 72,000 names are engraved on the limestone panels. The architectural design itself is moving. Its high arches reflect the missing space in lives after so many personal tragedies without even grave for compensation.

A departure from the grim narrative with a brief paleontological note: The Jurassic crinoid Apiocrinites can be identified in the steps of the memorial. I know it well from other contexts.

There is a very well maintained part of the 1916 battlefield at Beaumont-Hamel. Here the Newfoundland Regiment attacked the German lines on the first day of the first Battle of the Somme. The regiment was destroyed in less than twenty minutes after they emerged from their trenches. Six-hundred and seventy men were casualties.

These are remnants of the first line of British trenches.

The killing field of the Newfoundlanders. It is estimated 300-400 of their bodies still remain in the churned soil.

There was an original blasted trunk here called the Danger Tree. It is midway between the British and German lines, about as far as the Newfoundlanders got on July 1, 1916.

A caribou memorial faces the old German positions from the trenches of the Newfoundlanders. All the stones below it are from Newfoundland. The site is maintained by the government of Canada.

The end of my journey was to Hawthorn Ridge, site of a German position blown up by another British mine on the first day of the 1916 battle. The explosion was filmed.

This is the same perspective as the famous photographs and films of the 1916 Hawthorn Ridge explosion. The trees are growing on the crater rim.

This is a famous photo of British soldiers awaiting the Hawthorn mine explosion on July 1, 1916. They had tunneled out of a trench into a sunken lane in no-man’s-land to get as close to the German lines as possible for their attack.

That sunken lane is still present 101 years later.

I wanted to add more about the geology of the battlefield, but the human tragedy is so overwhelming I decided to leave it for later. For now, see the geological cross-section below. Also consider the remarkable observation that the intensity of the artillery bombardments actually changed the geology of the region. “Bombturbation” is a term that has been proposed in our clinical scientific way.

Wooster’s Fossil of the Week: A bored rhynchonellid brachiopod from the Middle Jurassic of France

July 22nd, 2016

1 Kutchi dorsal 585Another beautiful brachiopod this week from our friend Mr. Clive Champion in England. His donations to our collections have considerably enriched our teaching program, especially for brachiopods! This specimen is the rhynchonellid Kutchirhynchia morieri (Davidson, 1852) from the Middle Jurassic (Upper Bathonian) of Luc-sur-Mer, France. This is a view of the dorsal side with the dorsal valve on top with the ventral valve (containing the round opening from which the stalk-like pedicle extended) seen below it. Like most rhynchonellids, the valves have distinct plicae (thick ridges) where the shell is tightly folded.
2 Kutchi ventral 585This is the ventral view showing only the exterior of the ventral valve. Note the curved serpulid worm tube attached near the center, and the squiggly borings. These were likely sclerobionts (hard substrate dwellers) that occupied the brachiopod shell when the animal was still alive, since the dorsal and ventral valves are still articulated. The borings are probably of the ichnogenus Talpina, but I would have to grind down the shell to know for certain.
SSBuckmanThe genus Kutchirhynchia was named by Sydney Savory Buckman (1860-1929) in 1917. We met Buckman earlier in this blog when looking at another of his Jurassic rhynchonellid genera, Burmirhynchia. We learned a lot more about Buckman this summer during our expedition to the Jurassic of Dorset, where he did much of his work. He is best known there as an ammonite worker and stratigrapher (and massive taxonomic splitter).
3 Thomas DavidsonThe species Kutchirhynchia morieri was named by the Scottish paleontologist Thomas Davidson (1817-1885), who originally placed it in the large genus Rhynchonella. Buckman acknowledges Davidson in an ammonite monographs as one of his “earliest geological friends”. (Davidson was 43 years older than Buckman.) Davidson was born in Edinburgh to wealthy parents. He studied at the University of Edinburgh and then in France, Italy and Switzerland, where he made many long geological tours. He was convinced by the German paleontologist Christian Leopold von Buch (1774-1853) to work on fossil brachiopods. (Von Buch was 43 years older than Davidson. Nice to see the older generation having an effect on those kids!) Davidson stayed with brachiopods his entire career, producing massive monographs on both fossil and recent forms. He engraved his own plates on stone, and there are more than 200 of them. Davidson was elected a fellow of the Geological Society of London in 1852, awarded the Wollaston medal in 1865. In 1857 he was elected a Fellow of the Royal Society, receiving their Royal medal in 1870. Upon his death in Brighton, England, in 1885, his entire collection of fossil and recent brachiopods went to the British Museum.
4 Elizabeth GrayThis is a good place to mention Elizabeth Anderson Gray (1831-1924), an important fossil collector in Scotland who supplied Thomas Davidson and many other paleontologists with critical specimens for their work. She is one of the many unnoticed heroes of paleontology, being rarely acknowledged publicly and then overshadowed by her husband. She worked primarily in the Ordovician and Silurian and so did not give Davidson Jurassic rhynchonellids, but she provided hundreds of brachiopods from the early Paleozoic. I love this image of her knocking out fossils with a hammer, just like we do today. Trowelblazers has an excellent biographical page on Elizabeth Anderson Gray.

References:

Buckman, S.S. 1917. The Brachiopoda of the Namyau Beds, Northern Shan States, Burma. Palaeontologia lndica 3(2): 1-254.

Gilman, D.C., Thurston, H.T. and Colby, F.M., eds. 1905. Davidson, Thomas (paleontologist). New International Encyclopedia (1st ed.). New York: Dodd, Mead.

Shi, X. and Grant, R.E. 1993. Jurassic rhynchonellids: internal structures and taxonomic revisions. Smithsonian Contributions to Paleobiology, Number 73, 190 pages.

Wooster’s Fossil of the Week: A terebratulid brachiopod from the Middle Jurassic of northwestern France

April 29th, 2016

1 Cererithyris arkelli Almeras 1970 dorsal 585We have another beautiful brachiopod this week from our friend Mr. Clive Champion in England. He sent me a surprise package of fossils earlier this year. They are very much appreciated by me and my students!

The specimen above is Cererithyris arkelli Almeras, 1970, from the Bathonian (Middle Jurassic) of Ranville, Calvados, France. (Ranville, by the way, was the first village liberated in France on D-Day.) It is a terebratulid brachiopod, which we have seen before on this blog from the Miocene of Spain and the Triassic of Israel. They have the classic brachiopod form. The image above shows the dorsal valve with the posterior of the ventral valve housing the round hole for the fleshy stalk (pedicle) it had in life.
2 Cererithyris arkelli Almeras 1970 sideThis is a side view of C. arkelli. The dorsal valve is on the top; the ventral valve on the bottom. It is from this perspective that brachiopods were called “lamp shells” because they resemble Roman oil lamps.
3 Cererithyris arkelli Almeras 1970 ventralThis is the ventral view of the specimen. These brachiopods are remarkably smooth.
4 William_Joscelyn_ArkellCererithyris arkelli was named by Almeras (1970) in honor of William Joscelyn Arkell (1904–1958). Arkell was an English geologist who essentially became Dr. Jurassic during the middle part of the 20th Century. I’m shocked to see that with all his publications, awards and accomplishments, he died when he was only 54 years old.

W.J. Arkell grew up in Wiltshire, the seventh child of a wealthy father (a partner in the family-owned Arkell’s Brewery) and artist mother (Laura Jane Arkell). He enjoyed nature as a child, winning essay contests on his observations of natural history in his native county and south on the Dorset coast. Arkell was unusually tall for his age (6 feet 4.5 inches by age 17.5 years in an unusually detailed note) and was considered to have “outgrown his strength”. Nature and writing were escapes from athletic events. He also published poems.

Arkell attended New College, Oxford University, intending to become an entomologist, but Julian Huxley was his tutor and he quickly adopted geology and paleontology. Eventually he earned a PhD at Oxford in 1928, concentrating his research on Corallian (Upper Jurassic) bivalves of England. As a side project, he published work on Paleolithic human skeletons from northern Egypt.

Oxford suited Arkell, so he stayed there as a research fellow, expanding his research to the entire Jurassic System of Great Britain, then Europe, and then the world. His work became the standard for understanding Jurassic geology and paleontology for decades.

After World War II (in which he served in the Ministry of Transport), Arkell took a senior research position at Trinity College and the Sedgwick Museum, Cambridge University, continuing his work on the Jurassic. He travelled often, including long stints in the Middle East. His health was never good, though, and he had a stroke in 1956, and died after a second stroke in 1958.

During his career Arkell received the Mary Clark Thompson Medal from the National Academy of Sciences in the USA, a Fellowship in the Royal Society, the Lyell Medal from the Geological Society of London, and the Leopold von Buch medal from the German Geological Society.

References:

Almeras, Y. 1970. Les Terebratulidae du Dogger dans le Mâconnais, le Mont dʼOr lyonnais et le Jura méridional. Étude systématique et biostratigraphique. Rapports avec la paléoécologie. Documents des Laboratoires de Géologie Lyon, 39, 3 vol.: 1-690.

Arkell, W.J. 1956. Jurassic Geology of the World. New York; Edinburgh: Hafner Publishing Co; Oliver & Boyd; 806 pp.

Cox, L.R. 1958. William Joscelyn Arkell 1904-1958. Biographical Memoirs of Fellows of the Royal Society 4: 1.

Rousselle, L. and Chavanon, S. 1981. Le genre Cererithyris (Brachiopodes, Terebratulidae) dans le Bajocien supérieur et le Bathonien des Hauts-Plateaux du Maroc oriental. CR somm. Soc. Géol France, 1981: 89-92.

Wooster’s Fossil of the Week: An echinoid from the Eocene of France

July 7th, 2013

585 Echinolampas ovalis M Eocene Civrac-en-Médoc FranceThe above is a specimen of the echinoid Echinolampas ovalis (Bory de St Vincent, 1824) from the Eocene of Civrac-en-Médoc, France. We are looking at what is called the aboral surface — that part of the organism on the other side of its mouth. (I’m sure by now you recognize the little barnacle boring near the bottom of the skeleton.) Below is the oral view of the same specimen.585 Echinolampas ovalis M Eocene Civrac-en-Médoc France oral

Echinoids are a kind of echinoderm with a very long evolutionary history from the Ordovician to today. They include sea urchins, heart urchins and sad dollars, along with a few others. All echinoids are covered in life with numerous spines. These spines almost always fall off after the death of the organism, leaving the smooth test we see here. The tiny circles covering the surfaces of this specimen are spine attachments. In life this would have looked like a spiky ball.

In the center of the oral view is a large hole where the mouth was. The plates surrounding this are called the peristome (around-mouth). At the bottom on the oral view are two holes. The larger is where the anus was located (within the periproct of plates); the smaller is a circular boring, likely from a gastropod predator. Since the periproct is not in the center of the aboral surface, this is what is known as an irregular echinoid.
Echinolampas_ovalis_Eocene_Civrac-en-Médoc_France_CloseUp052013Above is a close-up of the center of the aboral surface. The radiating rows of holes were where tubefeet extended. These soft structures at the end of the water vascular system were used for locomotion, moving bits of food towards the mouth, and even respiration. The very center is a finely-porous plate called the madreporite (the opening for the water vascular system). The four holes around it are genital pores for releasing gametes into the water during reproduction. For a simple, globular organism, the echinoid is amazingly complex.
450px-Bory_Saint-Vincent_1778-1846Echinolampas ovalis was named by a scientist with a complex life story of his own. The dashing Jean Baptiste Bory de Saint-Vincent (1778-1846) was one of a remarkable generation of French zoologists. He began his career as a naturalist, studying the fauna on various French possessions in the Indian Ocean. He returned to France and became a soldier in the Napoleonic Wars, serving in the battles of Ulm (1805) and Austerlitz (1805), and participating in the disastrous French campaign in Spain. He was a Bonapartist to the end, opposing the Bourbon restoration, which resulted in exile from France. After his politics faded, he returned to France in 1820 and resumed his career as a traveling naturalist. He named dozens of living and fossil species of invertebrates after the wars, including our quiet little echinoid in 1824.

References:

Kier, P.M. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections 144(3), 262 pp.

Roman, J. 1965. Morphologie et evolution des Echinolampas (Echinides, Cassiduloides). Memoires du Museum National d’Histoire Naturelle, Nouvelle Serie, C, 15, 1-341.

Thum, A.B. and Allen, J.C. 1976. Reproductive ecology of the lamp urchin Echinolampas crassa (Bell), 1880 from a subtidal biogenous ripple train. Transactions of the Royal Society of South Africa 42: 23-33.

Wooster’s Fossil of the Week: Coated snails! (Middle Jurassic of France)

June 5th, 2011

In 1988 I had my first visit to France, hosted by my English friend Tim Palmer. We explored Bathonian (Middle Jurassic) limestones in Normandy tracking looking at hardgrounds and other hard substrates. Along the way we stopped in a quarry near the pretty little town of Aubry-en-exmes. There we found thousands of cylindrical white stones. Where broken, we could see they contained some sort of fossil in the center. When I got back to Wooster I cut a few open and polished them down to their centers, revealing the gorgeous snail shells seen above. The shells were originally the mineral aragonite now replaced with coarsely-crystalline calcite.

The snail is known as Bactroptyxis trachaea of the extinct Family Nerineidae in the informal group “Lower Heterobranchia” (which is still around). Cross sections of nerineids like this show their most distinctive feature: elaborate chamber walls inside the whorls of the shell (as seen in a close up below). It was once thought that these complicated structures evolved to strengthen the shell against shell-crushing predators, but now the most common view is that they held special digestive glands to enable them to exploit nutrient-poor organics on carbonate substrates (Barker, 1990).

There is another fossil type here as well: the thick, white calcareous coating of the snails. These are oncolites, a precipitate formed by cyanobacteria. The shells rolled around in a current as the bacteria added layer after layer of calcium carbonate, preserving the shells in such fine detail — and by the thousands.

Reference —

Barker, M.J., 1990. The palaeobiology of nerineacean gastropods. Historical Biology 3: 249-264.

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