A shelly bonanza from the Pleistocene of Sicily

June 5th, 2013

5. MegaraDitch060513NOTO, SICILY, ITALY–Our second stop of the day on this International Bryozoology Association field trip was in an unimpressive ditch (above) near Megara. But, of course, there is paleontological gold here: an assemblage of extremely well-preserved marine fossils.

6. AndrejMegara060513Colleague Andrej Ernst is examining a layer of shells extending the length of the drainage ditch.

7. SerpulidsMegara060513Her are some beautiful pectinid bivalves (scallops) with the treat for me: abundant serpulid worm tubes. There is an extensive sclerobiont (hard substrate dwelling) community on these shells.

7a. TurritellidsMegara060513Turritellid gastropods (snails) are extremely common in this assemblage. Note that several of these specimens have small holes drilled in them by predatory gastropods. We found naticid gastropods here too, which were probably the culprits.

8. HornedQuadrupedsMegara060513This mother lode of fossils was guarded by a herd of horned beasts. This one had a bell on it, so I assumed it was the most dangerous and stayed far away. (Love this new zoom lens!)

 

Sicilian fossils at last!

June 4th, 2013

FieldStopOne060413CATANIA, SICILY, ITALY–After lunch our International Bryozoology Association field trip actually collected fossil bryozoans. We visited a quarry exposure of Lower Pleistocene cemented marls rich in the bryozoan Celleporaria palmata (Michelin), along with many other species. These were apparently from a thicket of bryozoan colonies broken up in a storm and deposited as a debris flow down slope. The location is south of Catania at Pianometa.

Celleraria060413Lower Pleistocene Celleporaria palmata fragments at Pianometa. This was a very rapid-growing, branching bryozoan colony easily fragmented by storm currents.

Volcaniclastic060413Below those bryozoan-loaded beds is this unusual sequence. The darker layered units are volcaniclastic sediments derived from early eruptions from the Mount Etna complex. Occasionally boulders would roll downslope and be deposited as xenoliths (“foreign rocks”) Later the cemented sediments cracked repeatedly due to the intense earthquake activity associated with this tectonic boundary between the European and African plates. Those cracks filled with marly sediment from above.

SheepCheeseFarm060413The last visit of the day was to a sheep cheese farm. One sheep produces about a liter of sheep’s milk. The cheese we sampled (some more than others) is very soft — like cottage cheese without the lumps, or a soft ricotta. Interesting (and unpasteurized). We watched four rams beat each other bloody in an ongoing context monitored by large black dogs. I suppose it is part of the herding process, grim as it is.

Products of an angry giant

June 4th, 2013

SicilyCyclopeanIslands060413CATANIA, SICILY, ITALY–They may look like impressive sea stacks to you, but it turns out these are three huge stones thrown by the aggrieved and wounded cyclops Polyphemus at Odysseus as he escaped that infernal cave. Who knew?

This morning we traveled north of Catania to the Ciclopi Marine Protected Area near Aci Castello and Aci Trezza to look at the evidence of the ancient volcanic activity that led to Mount Etna, and to snorkel and dive on the life-encrusted rocks in the blue, blue waters.

Island060413We took a boat ride all of about 300 meters across the bay to the tiny island of Lachea, shown above. Notice that there is a crack running through the rocks seen just above the boat. This is an active fault that runs through the middle of the island. Also note that there is a mix of light and dark rocks visible.

IslandBasalticIntrusion060413Lachea is a combination of whitish marls and claystones above with black basalt injected from below. This is the very beginning of volcanic activity in this region as hot magma began to work its way into the overlying sediments of a shallow sea. When the lava erupted onto the seafloor, masses of pillow basalts formed (see previous post). The cyclopean rocks in the top image are eroded roots of the massive basalt flows. They show beautiful columnar jointing.

Etnafromisland060413From Lachea we can see the glowering outline of Mount Etna, the true giant in our story.

StationSign060413The island of Lachea and its surrounding rocks has been the site of a research station for over a century. The fauna and flora of both the island and the seafloor down to 110 meters are protected by law.

IslandLizard585This pretty green lizard is common on Lachea and apparently endemic (found only there). It is Podarcis sicula ciclopica. Its mating season of three months is about to begin, so there was much lizardly activity.

Grotto060413One of the first places we visited on the island was this tiny historical grotto. Only five of us could crawl into this completely dark chamber at a time. Once inside you can carefully stand up and (at least some of us) touch your head on the ceiling. That turned out to be a mistake because the guiding biologists then show you the unique cave spiders hanging on their webs about your ears!

Lunch060413Finally I must show you at least one of our large Sicilians lunches, this one back in Catania after our morning marine excursion. We are eating well, if a bit later than usual — and with much more time in the process!

 

Wooster’s Fossil of the Week: Cast of a lower jawbone of the largest ape ever (Pleistocene, southern China)

March 17th, 2013

Gigantopithecus_blacki_mandible_010112The above is one of my favorite “fossils”, a commercially-available cast of the lower jawbone of Gigantopithecus blacki, a giant extinct ape. It was produced from an actual Pleistocene fossil found in a cave near Liucheng, Guangxi, in southern China. I like it especially because it is sometimes associated with the mythical “Bigfoot”.

Gigantopithecus blacki was the largest ape that ever lived: up to three meters tall and weighing over 500 kilograms. (G. blacki is known only from teeth and mandibles such as that shown above, so these size estimates are based on scaling.) It was a contemporary with early versions of our own species, which must have led to a few astounding encounters for our ancestors. G. blacki was two or three times heavier than the largest gorillas today.

Gigantopithecus blacki appears to have lived in bamboo forests. Striations on its teeth, and the occasional phytolith stuck in the enamel, shows that this species was a vegetarian. It may have even had a lifestyle much like today’s pandas.

The molars of Gigantopithecus blacki look surprisingly like ours with their multiple cusps and broad surfaces. This is the result of convergent evolution and not an indication of a recent common ancestry. (They are analogous features, not homologous.) G. blacki is now classified in the Subfamily Ponginae with their cousins the orangutans.

What is most fun about Gigantopithecus these days is its association with the “Bigfoot” illusion. Look at how seriously the people at the “Bigfoot Field Researchers Organization” take the possible connection of Gigantopithecus and Bigfoot. Despite their objections, we really can wonder why we’ve never found evidence of this giant ape in North America, including bones, teeth, legitimate footprints or real photographs. A living three-meter tall ape is a bit difficult for science to have missed! (Unless, of course, Bigfoot has supernatural powers.)

References:

Coichon, R. 1991. The ape that was – Asian fossils reveal humanity’s giant cousin. Natural History 100: 54–62.

Ciochon, R., et al. 1996. Dated co-occurrence of Homo erectus and Gigantopithecus from Tham Khuyen Cave, Vietnam. Proceedings of the National Academy of Sciences of the United States of America 93: 3016–3020.

Jin, C., et al. 2009. A newly discovered Gigantopithecus fauna from Sanhe Cave, Chongzuo, Guangxi, South China. Chinese Science Bulletin 54: 788-797.

Wooster’s Fossil of the Week: A crab from the Pleistocene of northern Australia

November 18th, 2012

Isn’t this amazing preservation? This fossil crab, which we received as a donation a few years ago, is Macrophthalmus latreillei (Desmarest, 1822) from the Pleistocene of northern Australia. It is virtually identical to its modern counterpart of the same species, Latreille’s Sentinel Crab.

M. latreillei has large, stalked eyes. It likes to hide under a layer of sand with its eyes sticking out looking for predators. It is mostly active in the night, burrowing through the sediment collecting deposited organic material. It is found throughout the Indo-Pacific region.

The modern crab species M. latreillei was named in 1822 by the French zoologist Anselme Gaëtan Desmarest (1784–1838), shown above. He was a student of two other famous French scientists: Georges Cuvier and Alexandre Brongniart. He was the Professor of Zoology at the École nationale vétérinaire d’Alfort, succeeding the zoologist Pierre André Latreille (1762-1833), for whom he named this crab.
Latreille (above) was a most interesting fellow. He was an entomologist and a specialist in crustaceans. In 1786, when he was 24 years old, he was ordained a priest. This turned out, in hindsight, to be an almost fatal mistake. He was arrested by French revolutionaries in 1794 on suspicion of being a counter-revolutionary monarchist cleric (which he likely was). He was sentenced to deportation to a miserable tropical island prison. Just before he was scheduled to be shipped away, his jailers found him carefully studying a beetle crawling across his grungy cell floor. The authorities thought he had gone crazy in prison, but Latreille announced that the insect was a very rare species. This got back to an expert who confirmed the beetle as Necrobia ruficollis. Other experts then intervened to rescue the perceptive Latreille from prison and a tropical grave. To this day an image of this beetle is engraved on Latreille’s tombstone in Paris. Taxonomy saved a life.

References:

Barnes, R.S.K. 1967. The Macrophthalminae of Australia, with a review of the evolution and morphological diversity of the type genus Macrophthalmus (Crustacea: Brachyura). Transactions of the Zoological Society of London 31: 195-262.

Dupuis, C. 1974. Pierre André Latreille  (1762-1833): the foremost entomologist of his time. Annual Review of Entomology 1974: 1-13.

Wooster’s Fossil of the Week: A mastodon tusk (Late Pleistocene of Holmes County, Ohio)

June 24th, 2012

This long and weathered tusk sits in a display case outside my office. It is from the American Mastodon (Mammut americanum) and was found many decades ago in Holmes County, just south of Wooster. A tooth found with it was a previous Fossil of the Week. Such tusks are rather rare because the ivory tends to disintegrate faster than tooth and bone. Our specimen is, in fact, hollow and held together by wires.
Above is a closer view of the proximal end of the tusk (the part closest to the face). You can see the hollowness and, curiously, that the ivory is charred. I used to tell students that the mastodon must have been hit by lightning, but I stopped when they took me too seriously!

This gives me a chance to mention a mastodon specimen I recently saw in a visit earlier this month to this famous place:
Monticello is, of course, the home of Thomas Jefferson, a Founding Father and the third president of the United States. Jefferson was a science enthusiast, and paleontology was one of his passions. He was fascinated with ancient life, and some have considered him the first American paleontologist. One room of the White House, for example, appears to have been devoted to his fossil bone collection.

Mastodons were particularly interesting to Jefferson because of an odd idea that was in vogue in France at the time. Georges-Louis Leclerc, Comte de Buffon, a famous French naturalist, wrote that “a niggardly sky and an unprolific land” caused life in the New World to be weak, small and degenerate. Life in North America was considered by the French to be quite inferior to that in Europe. Jefferson knew, of course, this was nuts. Having the bones of a North American elephant, as large or larger than any other elephants, would show the Frenchies how wrong they were. And Buffon eventually agreed, although he died before he could correct his books.
Above is a lower jawbone of Mammut americanum in Monticello. I wish I could have taken my own photograph, but this was not allowed. I’ve had to make do with one of their images online.

Curiously, Jefferson had one serious deficit when it comes to calling him a paleontologist. He apparently did not believe that species ever go extinct. When he dispatched Lewis and Clark on their expedition, for example, he expected them to find living mastodons deep in the American interior. Too bad they didn’t!

References:

Conniff, R. 2010. Mammoths and Mastodons: All American Monsters. Smithsonian Magazine, April 2010.

Semonin, P. 2000. American Monster: How the Nation’s First Prehistoric Creature Became a Symbol of National Identity. New York University Press, New York, 502 pages.

Thomson, K.S. 2008. The Legacy of the Mastodon: the Golden Age of Fossils in America. New Haven, Connecticut, Yale University Press.

Wooster’s Fossil of the Week: a nestling bivalve (Pleistocene of The Bahamas)

April 22nd, 2012

This weathered and encrusted shell was pulled from a round hole bored in a Pleistocene reef (about 125,000 years old) exposed on San Salvador Island, The Bahamas. It is Coralliophaga coralliophaga (Gmelin 1791), a derived venerid bivalve (a type of heterodont, meaning that it has cardinal and lateral articulating teeth inside its valves.) I collected it back in 1991 while studying an inter-reef unconformity that recorded a drop and rise of sea level (Wilson et al., 1998; Thompson et al., 2011).

Coralliophaga means “coral eater”, which is a bit of a bum rap for this clam. It is found inside borings in coral, true enough, but those holes were drilled by some other types of clams. C. coralliophaga only occupies the holes after the original dweller is dead and gone (Morton, 1980). We call this kind of behavior “nestling“, which seems a polite way of saying “squatting”. These bivalves grew to adulthood in these cavities protected from most predators as they filtered the seawater for food.
The trace fossil Gastrochaenolites torpedo (the elongate borings) with a nestling (and broken) C. coralliophaga in the lower right corner.

The posterior ends of these shells are encrusted by a variety of calcareous algae and other organisms during life, so they look a bit rough on their outsides. Often the encrustations are so thick that the shells are difficult to extract from the holes, so getting a nice complete shell like the one at the top of this entry is rare.
C. coralliophaga was named by Johann Friedrich Gmelin (1748–1804) in 1791. Gmelin was an accomplished naturalist from Tübingen, Germany. He received an MD degree in 1769, with his father (Philipp Gmelin) as his advisor. He taught at Tübingen and the University of Göttingen, writing many textbooks in fields from chemistry through botany. He published the 13th edition of Systema Naturae by Carolus Linnaeus, inserting his new taxa in the text, including our new friend Coralliophaga coralliophaga.

References:

Gmelin, J.F. 1791, in Linnaeus, C. Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis. 13th Edition, Lyon : J.B. Delamolliere Tom.

Morton, B. 1980. Some aspects of the biology and functional morphology of Coralliophaga (Coralliophaga) coralliophaga (Gmelin, 1791) (Bivalvia: Arcticacea): a coral-associated nestler in Hong Kong. pp. 311-330, in: Morton, B., The Malacofauna of Hong Kong and southern China. Proceedings of the First International Workshop on the Malacofauna of Hong Kong and Southern China, Hong Kong, 1977. Hong Kong: Hong Kong University Press.

Thompson, W.G., Curran, H.A., Wilson, M.A. and White, B. 2011. Sea-level oscillations during the Last Interglacial highstand recorded by Bahamas corals. Nature Geoscience 4: 684–687.

Wilson, M.A., Curran, H.A. and White, B. 1998. Paleontological evidence of a brief global sea-level event during the last interglacial. Lethaia 31: 241-250.

Sand and Gravel in the Holmesville Moraine

April 13th, 2012

The College of Wooster Geomorphology class set out to explore the Holmesville Moraine, a 20 minute drive south of Wooster straight down the Killbuck River Valley. It was a beautiful day, except for the rain. The first stop was Holmesville Sand and Gravel, a company which mines and sorts the deposit and sells it for various building and homeowner applications. We ended up classifying this as a Kame Moraine as most of the sediment is sand and gravel intermixed with diamict all piled up into a great cross valley ridge. This is likely the dam for Glacial Lake Killbuck, which was impounded to the north.

The Separator – This machine and associated conveyors sorts the gravel from the sand from the silt.

Sorted piles – note the varying angles of repose.

 

 

 

 

 

 

 

 

 

 

 

 

 

The dredge sucks sand from 70 feet down in this lake. It is then piped to the Separator.

 

Fine-grained sand and silt is returned to the lake – note the delta. A wave-dominated delta that is revealed with a modest drop in lake level.

Continue reading this post to see why the group is dumbfounded.

Ice-contact stratified drift – sediments range from diamicts to stratified sands and gravels. Many of the gravels are cemented. Note that the lower left is a bedrock contact. This is the guts of the kame moraine.

Cemented sand and gravel – note the evenly-space joints where the rivelets have excavated the materials – joints from unloading?

Cemented and partially stratified diamict – this unit is a major challenge to remove in mining.

Raindrop imprints on mudcracks.

Ditch draining the floor of former Glacial Lake Craigton – note the peaty sediments and the tiles. Note the meandering thalweg within the ditch.

Wooster’s Fossils of the Week: Sponge and clam borings that revealed an ancient climate event (Upper Pleistocene of The Bahamas)

September 11th, 2011

This week’s fossils celebrate the publication today of a paper in Nature Geoscience that has been 20 years in the making. The title is: “Sea-level oscillations during the Last Interglacial highstand recorded by Bahamas coral”, and the senior author is the geochronological wizard Bill Thompson (Woods Hole Oceanographic Institution). The junior authors are my Smith College geologist friends Al Curran and Brian White and me.

The paper’s thesis is best told with an explanation of this 2006 image:
This photograph was taken on the island of Great Inagua along the coast. The flat dark surface in the foreground is the top of a fossil coral reef (“Reef I”) formed during the Last Interglacial (LIG) about 123,000 years ago. It was eroded down to this flat surface when sea-level dropped, exposing the reef to waves and eventually terrestrial weathering. The student sitting on this surface is Emily Ann Griffin (’07), one of three I.S. students who helped with parts of this project. (The others were Allison Cornett (’00) and Ann Steward (’07).) Behind Emily Ann is a coral accumulation of a reef (“Reef II”) that grew on the eroded surface after sea-level rose again about 119,000 years ago. These two reefs show, then, that sea-level dropped for about 4000 years, eroding the first reef, and then rose again to its previous level, allowing the second reef to grow. (You can see an unlabeled version of the photograph here.) The photograph at the top of this post is a small version of the same surface.

The significance of this set of reefs is that the erosion surface separating them can be seen throughout the world as evidence of a rapid global sea-level event during the Last Interglacial. Because the LIG had warm climatic conditions similar to what we will likely experience in the near future, it is crucial to know how something as important as sea-level may respond. The only way sea-level can fluctuate like this is if glacial ice volume changes, meaning there must have been an interval of global cooling (producing greater glacial ice volume) that lowered sea-level about 123,000 years ago, and then global warming (melting the ice) that raised it again within 4000 years. As we write in the paper, “This is of great scientific and societal interest because the LIG has often been cited as an analogue for future sea-level change. Estimates of LIG sea-level change, which took place in a world warmer than that of today, are crucial for estimates of future rates of rise under IPCC warming scenarios.” With our evidence we can show a magnitude and timing of an ancient sea-level fluctuation due to climate change.

Much of the paper concerns the dating techniques and issues (which is why Bill Thompson, the essential geochronologist, is the primary author). It is the dating of the corals that makes the story globally useful and significant. Here, though, I want to tell how the surface was discovered in the first place. It is a paleontological tale.

In the summer of 1991 I worked with Al Curran and Brian White on San Salvador Island in The Bahamas. They were concentrating on watery tasks that involved scuba diving, boats and the like, while I stayed on dry land (my preferred environment by far). I explored a famous fossil coral exposure called the Cockburntown Reef (Upper Pleistocene, Eemian) that Brian and Al had carefully mapped out over the past decade. The Bahamian government had recently authorized a new harbor on that part of the coastline and a large section of the fossil reef was dynamited away. The Cockburntown Reef now had a very fresh exposure in the new excavation quite different from the blackened part of the old reef we were used to. Immediately visible was a horizontal surface running through the reef marked by large clam borings called Gastrochaenolites (see below) and small borings (Entobia) made by clionaid sponges (see the image at the top of this post).
Inside the borings were long narrow bivalve shells belonging to the species Coralliophaga coralliophaga (which means “coral eater”; see below) and remnants of an ancient terrestrial soil (a paleosol). This surface was clearly a wave-cut platform later buried under a tropical soil.


My colleagues and I could trace this surface into the old, undynamited part of the Cockburntown Reef, then to other Eemian reefs on San Salvador, and then to other Bahamian islands like Great Inagua in the far south. Eventually this proved to be a global erosion surface described or at least mentioned in many papers, but its significance as an indicator of rapid eustatic sea-level fall and rise was heretofore unrecognized. Finally getting uranium-thorium radioactive dates on the corals above and below the erosion surface placed this surface in a time framework and ultimately as part of the history of global climate change.

This project began 20 years ago with the discovery of small holes left in an eroded surface by humble sponges and clams. Another example of the practical value of paleontology.

References:

Thompson, W.G., Curran, H.A., Wilson, M.A. and White, B. 2011. Sea-level oscillations during the Last Interglacial highstand recorded by Bahamas coral. Nature Geoscience (DOI: 10.1038/NGEO1253).

White, B.H., Curran, H.A. and Wilson, M.A. 1998. Bahamian coral reefs yield evidence of a brief sea-level lowstand during the last interglacial. Carbonates and Evaporites 13: 10-22.

Wilson, M.A., Curran, H.A. and White, B. 1998. Paleontological evidence of a brief global sea-level event during the last interglacial. Lethaia 31: 241-250.

Wooster’s Fossil of the Week: A woolly mammoth tooth (Late Pleistocene of Holmes County, Ohio)

March 27th, 2011

Since we had a mastodon tooth as our last Fossil of the Week, paleontological symmetry demands we have a mammoth tooth this week. The fossil above also comes from the productive bogs of Holmes County a few miles south of Wooster.

Our tooth is from a young woolly mammoth (Mammuthus primigenius). These were true elephants, unlike the mastodons which were only distant cousins in another family. You can tell a mammoth tooth from a mastodon tooth by the flat ridges on its chewing surface rather than pointy cusps.

The woolly mammoth had long tusks (one of which we have in a display case outside my office) and, of course, plenty of long hair to keep it warm in the tundra environments it inhabited. They were grazers, apparently digging up grass and other ground vegetation with their tusks.

Mammuthus primigenius appeared about 150,000 years ago during the Pleistocene, and the last individual died surprisingly only 3700 years ago on a small Alaskan island. They are well known from frozen remains in Siberia — and from a new Japanese attempt to clone them from frozen tissue. (I’ve heard that one so many times …)

In June 2008, a Wooster Independent Study team saw cross-sections of mammoth footprints at The Mammoth Site, Hot Springs, South Dakota (see below). They could only be identified as such because of the dozens of mammoth skeletons around them!

Woolly mammoths in northern Spain (from a mural by Mauricio Antón).

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