Wooster’s Fossils of the Week: ribbed brachiopods (Middle Jurassic of Israel)

July 15th, 2012

These delightful brachiopods are from the Matmor Formation (Jurassic, Callovian) of the Negev in southern Israel. They are part of a long-term Wooster project describing and interpreting a diverse paleocommunity. The latest trip to study these fossils was this past March with Melissa Torma and our Israeli colleague Yoav Avni. The shells above are Burmirhynchia jirbaenesis Muir-Wood 1935. We identified them using the excellent work on Matmor brachiopods by Feldman et al. (2001).

The location in Makhtesh Gadol, Negev, Israel, where these specimens were collected.

Burmirhynchia jirbaensis was originally named from a collection of specimens found in the Biheh Limestone of the Jirba Range in British Somaliland (modern-day Somalia). This is a wonderful place for Jurassic paleontology, but not one I’m likely to visit soon!

Burmirhynchia is an important brachiopod in the Jurassic of the Tethyan Realm. It has been found throughout the Middle East, southern Europe, Africa and Australia. It has, apparently, been overly “split” into over 90 species, most of which are dubious at best (Shi and Grant, 1993). B. jirbaensis, though, is a legitimate species based on internal characteristics you can only see by sectioning or internal tomography (Feldman et al., 2001).

The genus Burmirhynchia was described in 1918 by an interesting character: Sydney Savory Buckman (1860-1929). Buckman is best known for his work on ammonites, but he was also a novelist, social reformer and (gasp) a fossil dealer (to support his geological work). He was born in Cirencester, England, but grew up in Dorset among some of the most spectacular Jurassic geology in the world. Buckman was briefly a farmer, but he most enjoyed amateur geology and working on collections in local museums. Ammonites were his passion — he worked on several large monographs describing hundreds of new species. (The complaints about his taxonomic splitting began then.) His most eccentric idea was that ammonites may have suffered from a kind of flatulence produced by “nervous apprehension of danger”, with the resulting gas increasing their buoyancy and helping them flee to safety. I don’t recall hearing that one in school!

Curiously enough, Sydney Savory Buckman made one progressive addition to the vocabulary of paleontology: in 1893 he invented the term “palaeo-biology” (Sepkoski, 2012).

References:

Buckman, S.S. 1918. The Brachiopoda of the Namyau Beds, Northern Shan States, Burma. Memoirs of the Geological Survey of India, Palaeontologia lndica, new series 3: 1-299.

Feldman, H.R., Owen, E.F. and Hirsch, F. 2001. Brachiopods from the Jurassic (Callovian) of Hamakhtesh Hagadol (Kurnub Anticline), southern Israel. Palaeontology 44: 637–658.

Sepkoski, D. 2012. Rereading the Fossil Record: The Growth of Paleobiology as an Evolutionary Discipline. University Of Chicago Press, Chicago, 440 pages.

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

Wooster’s Fossils of the Week: Wiggly little foraminiferans from the Middle Jurassic of southern England

July 1st, 2012

These shell fragments are of the oyster Praeexogyra hebridica var. elongata, and I picked them up long ago from a remarkable unit made almost entirely of them. It is the Elongata Bed at the base of the Frome Clay (Middle Jurassic) near Langton Herring in Fleet Lagoon, Dorset, England. (See House (1993) for more details, and this site has a nice geological map.) Nearly every oyster piece is covered with elongated, flaky white encrusters easily overlooked. They are attached foraminiferans known as Vinelloidea crussolensis Canu, 1913. (I labelled the specimens with the better-known name “Nubeculinella Cushman, 1930″ when I collected them. Voigt (1973) had earlier shown that this genus is a junior synonym of Vinelloidea. I should have known better.)

Vinelloidea is in the Order Miliolida of the Foraminifera. It is a very common sclerobiont in shallow water Jurassic and Cretaceous deposits, especially in western Europe. Curiously, I’ve not yet seen it in the Jurassic or Cretaceous of Israel, and I’ve looked very hard at the encrusting faunas there. Vinelloidea grew as a series of glassy chambers across shells, pebbles and hardgrounds (Reolid and Gaillard, 2007; Zaton et al., 2011). When the conditions were right, as they were in the Middle Jurassic in southern England, it could be one of the most abundant encrusting organisms in life’s history.

References:

Canu, F. 1913. Contribution à l’étude des Bryozoaires fossiles XIII. Bryozoaires jurassiques. Bulletin de la Société géologique de France, série 4, 13:267-276.

Cushman, J.A. 1930. Note sur quelques foraminifères jurassiques d’Auberville (Calvados). Bulletin de la Société linnéenne de Normandie, série 8, vol. 2 (1929): 132-135.

House, M.E. 1993. Geology of the Dorset Coast. Geologists Association Guide No. 22. 2nd edition, 164 pages.

Reolid, M. and Gaillard, C. 2007. Microtaphonomy of bioclasts and paleoecology of microencrusters from Upper Jurassic spongiolithic limestones (External Prebetic, southern Spain). Facies 53: 97-112.

Voigt, E. 1973. Vinelloidea Canu, 1913 (angeblich jurassische Bryozoa Ctenostomata) = Nubeculinella Cushman, 1930 (Foraminifera). Paläontologische Abhandlungen 4: 665-670.

Zaton, M., Machocka, S., Wilson, M.A., Marynowski, L. and Taylor, P.D. 2011. Origin and paleoecology of Middle Jurassic hiatus concretions from Poland. Facies 57: 275-300.

Wooster’s Fossils of the Week: dinosaur gastroliths (Jurassic of Utah, USA)

June 10th, 2012

These rounded stones are labeled in our collections as gastroliths (literally “stomach stones”) from Starr Springs near Hanksville, Wayne County, Utah. I’m featuring them this week in honor of our Utah Project team working right now in the baking Black Rock Desert near Fillmore, Utah.

From their reported location, these stones are likely out of the Summerville Formation (Middle-Upper Jurassic) and, in another plausible supposition, probably from some sort of dinosaur. Sometimes we just have to trust the labels on our specimens, at least for educational purposes!

My friend Tony Martin recently wrote an excellent blog post on gastroliths, so I won’t repeat his insights here. The general wisdom is that these stones were consumed by herbivorous dinosaurs to aid in their digestion. They would have lodged them in the equivalent of a gizzard and used them to grind their food, much like modern birds. (And yes, dinosaurs were birds themselves.) Gastroliths usually have a resistant lithology to be useful as grinders. The gastroliths above are chert, one of the hardest rock types.

Identifying gastroliths correctly is a bit of a challenge if you don’t find them inside a dinosaur skeleton. The most common indicators are that they are very smooth, are in a location where they were unlikely to have been transported inorganically, and are of a lithology unlike the surrounding rock (“exotics” as geologists like to call them). Still, even with all these criteria met, we must be a tad suspicious if we didn’t find them associated with dinosaur bones. I would never, for example, buy a gastrolith in a rock shop. Without context, it could be just a stream-worn stone. I’m trusting the label on ours that we have the real deal!

References:

Stokes, W.L. 1987. Dinosaur gastroliths revisited. Journal of Paleontology 61: 1242-1246.

Wings, O. 2007. A review of gastrolith function with implications for fossil vertebrates and a revised classification. Acta Palaeontologica Polonica 52: 1-16.

Wooster’s Fossils of the Week: A calcareous sponge with a crinoid holdfast (Matmor Formation, Middle Jurassic, Israel)

April 8th, 2012

The Class Calcarea of the Phylum Porifera is a group of sponges characterized by spicular skeletons made of calcium carbonate (calcite in this case). The spicules (small elements of the skeleton) are often fused together, causing the sponges to look a bit like corals or bryozoans. They are among the most common fossils in the Matmor Formation (Middle Jurassic, Callovian) of southern Israel. Melissa Torma and I collected this particular fossil on our expedition last month. It is another indication that the Matmor Formation was deposited in very shallow waters.
This is the underside of the Matmor calcareous sponge. (I wish we had a name for it, but the taxonomy is in considerable flux right now.) You can see the way it grew radially around an encrusting center. In the lower right a circular oyster attachment is visible.
A close view of the top surface of the calcareous sponge showing radiating canals called astrorhizae. They were used to channel water currents for the sponge’s filter-feeding system.
This crinoid holdfast (the base of an attaching stem) locked onto the calcareous sponge after its death. We can tell this because it is bound to the spicular skeleton itself, which was only exposed after the sponge’s soft tissues rotted away. It is not possible to identify the crinoid, but it is likely in the genus Apiocrinites.
The Class Calcarea was named by James Scott Bowerbank in 1864. Bowerbank (1797-1877) was an English naturalist born in London. He helped run a distillery with his brother, making enough money to support his diverse interests in natural history. He collected many fossils in his life, specializing in the London Clay (Eocene). His various publications gained him membership in the Royal Society in 1842. His greatest work was probably a four-volume set titled “A Monograph of the British Spongidae”. (You can read at least part of this work online.) He was well known as a strong supporter of young scientists, opening his home and collections (and use of his valuable microscopes) to all those seriously interested in natural history. I like to think he would have been happy as a liberal arts geology professor!

Wooster’s Fossil of the Week: A curving scleractinian coral (Middle Jurassic of Israel)

March 18th, 2012

Since Melissa Torma and I recently returned from our expedition to southern Israel (see immediately previous posts), I thought our weekly fossil highlight should be one of our specimens collected from the Middle Jurassic Matmor Formation of Makhtesh Gadol.

This is a colonial scleractinian coral, a group that first appeared in the Triassic. It was originally made of aragonite and is now recrystallized to calcite. The exterior is well preserved, but the interior is coarsely crystalline. You can just make out faint outlines of the individual corallites that make up the colony.

The distinctive feature of this specimen is that it shows different growth directions. Apparently it was disturbed on the seafloor as it grew, so it periodically had to change its direction to keep growing upwards towards the sunlight. It needed the light because it had photosynthetic symbionts in its tissues.

This coral is one of many indications of the shallow paleoenvironment we’ve proposed for the Matmor Formation. It is also encrusted by a variety of sclerobionts, so it is a bit of a community all on its own.

 

A field day cut short by angry camels and a threat of rain … but at least the dust is gone!

March 15th, 2012

MITZPE RAMON, ISRAEL–Compare the image above to the one taken in the same place two days ago. Much better! Our only dust today was a local product from the unending winds. The Saharan dust is gone. We paid for this clarity, however, with a dramatic drop in temperature. It was 8°C (46°F) when we started work this morning. This is typical for spring fieldwork in the northern Negev. The weather is less predictable, and the temperatures can swing wildly from day to day. The summers are very predictable: sunny, hot, dry, and not a breeze. I don’t take my hat’s chinstrap in the summers, but in the spring it is tied firmly all day.

Our goal today was to travel as far south as we could along the strike of the Matmor Formation, sampling “subunit 51″ when we could. Melissa and I walked into the makhtesh about five kilometers. This was not a long distance, but in the summer we just couldn’t carry enough water to pull it off without a four-wheel drive vehicle.

We walked south from the Negev Minerals mine, where we park, along an old pipeline road until we reached Wadi Hatira (shown above). This is the wadi that drains the makhtesh through its single opening in the northeast. It is the greenest zone in the structure because it has the most soil moisture. There were some beautiful flowers along its banks, photos of which I’ll post later. From the wadi we climb up to the old British road and continue south into the Matmor Hills.

Melissa is standing above at the base of Subunit 51 of the Matmor Formation (Middle Jurassic). This is typical of its exposure in the central part of the makhtesh where there is higher relief in the Matmor Hills. The unit is difficult to follow because of an abundance of small faults cutting perpendicular to strike. Its marly nature means it is often covered with debris from the units above. The northern outcrops have lower relief, which in our case means we have more gentle slopes to search for fossils.

Around noon we ran into a camel herd wandering around our outcrops. (The most active of the beasts is shown above.) They had calves with them and were immediately disturbed by our appearance. They started to make angry camel noises. We did not want a run in with riled-up camels, nor did we want to give their Bedouin herdsmen any reason to think we were harassing them. Since the camels weren’t going anywhere, we reluctantly turned around and headed back.

To aid our decision to retreat, the skies looked very threatening (see above). Rain? Who would have thought? We could smell rain and see what looked like rain to the northeast. We did not want to be in a big rock bowl if it really did pour, so we hastened back to the car. It didn’t actually rain on us, but it may have in the makhtesh after we left.

We got a minimum amount of work done today, though, so it was not a loss. Now we’re back in our warm rooms listening to the wind continue to howl outside.

Wooster Geologists in Paleontological Heaven

March 14th, 2012

MITZPE RAMON, ISRAEL–The above is an untouched view of an eroding marl of the Matmor Formation (Middle Jurassic) in Makhtesh Gadol. I simply placed a one shekel coin in the scene for scale. This is why we love this place — the fossils are just rolling out of the outcrops (once you know where to look). Our ultimate goal is to describe the communities in this particular unit, and you can see that we have rich material to work with. You can try to identify the fossils you see here. I’ll give the answers below!

Melissa walking across the northern end of Makhtesh Gadol through the middle part of the Matmor Formation. You can see in the distance that dust (and the wind that brought it) is still an issue.

Ready for the answers to the fossil quiz above? 1 = scleractinian coral; 2 = Apiocrinites (crinoid) calyx base; 3 = Apiocrinites calyx plate; 4 = terebratulid brachiopod; 5 = Apiocrinites stem fragment; 6 = echinoid spine; 7 = oyster; 8 = Apiocrinites calyx plate; 9 = another kind of oyster.

In a close-up yet another type of brachiopod is visible. The red circle shows a thecideide brachiopod (no doubt Moorellina negevensis) attached to a crinoid column.

Cool, eh? And this is just a taste of what we saw today. Heaven indeed.

Another dusty day of fieldwork in the makhtesh

March 13th, 2012

MITZPE RAMON, ISRAEL–It was a little warmer today in Makhtesh Gadol, but the sun was still obscured by the dust blown across the southern Mediterranean from the Sahara Desert. I may have an innate tolerance for dust from my childhood in the Mojave Desert, but this particular dust triggers a kind of hay fever for me. Maybe it is because Saharan dust is rumored to have a significant fraction of insect parts!

The top image is from the Mt. Avnon overview of Makhtesh Gadol (looking south along the west wall). The road below was built by the British in the early 1940s in an attempt to find and exploit oil from the makhtesh structure. The road is very well built and has survived with relatively little repair beyond paving it. It is astonishingly narrow, though, especially when you meet large mining trucks and tour buses on it. The trip down the most challenging portion was immortalized in a 2011 movie by filmaker Will Cary. Note the blue skies that summer.

Melissa and I located a series of outcrops in the Matmor Formation (Middle Jurassic) exposing “subunit 51″, which has a diverse crinoid-brachiopod community preserved in it. This assemblage has a very patchy distribution, so we want to see as many exposures of it we can to make certain we’ve collected a representaive fossil fauna. Ordinarily our outcrops of this marly subunit look like the one above. The yellow-brown color is distinctive, so it is relatively easy to find throughout the area. There is no hope, though, of seeing sedimentary and paleontological structures in such a loose sediment — it simply erodes too quickly.

We found one site, though, where subunit 51 is preserved in a cliff (above), which prevented it from disintegrating in the usual manner. From Melissa’s hat on down is the top portion of this critical marl. We could see no structures in the featureless marl itself, but on the base of the limestone above there are infillings of a trace fossil known as Thalassinoides. These were probably created by burrowing crustaceans (likely shrimp) that dug down into the very top of our subunit 51 mud.

Our favorite fossil find of the day is this little rhynchonellid brachiopod shown below (likely Burmirhynchia) with a round hole in its dorsal valve. It is tempting to say this is a predatory borehole — the work of a carnivore of some kind — but we can’t tell for certain. It is not beveled on its periphery, so we can’t distinguish it from just a hole punched after death through the vicissitudes of burial, preservation or exposure. Still, it is fun to think of it as a fossil predatory interaction.

 

A dusty but successful start on field work in southern Israel

March 12th, 2012

MITZPE RAMON, ISRAEL–Melissa Torma, our friend Yoav Avni (Geological Survey of Israel), and I just ended a productive first day in the field. The two of them are shown above in classic paleontological poses. They are collecting fossils from Subunit 51 of the Matmor Formation (Middle Jurassic) in Hamakhtesh Hagadol in the northern Negev. We found excellent crinoid stems and calyx plates, brachiopods, corals, sponges, echinoid spines, serpulid worms, clams, and oysters.The day was very windy but seasonably cool.

You might be wondering why the sky in the above photograph is not the usual bright blue for this region? It is because the air is filled with dust blown off the Sahara Desert to the eastern Mediterranean countries (see NASA image below from 2011). This is a common occurrence here in the spring when a storm system is on its way. In the course of a year, every square kilometer in Israel receives 30-60 tons of this dust. The storm will bring rain to northern Israel tomorrow and Wednesday, but it is very unlikely to break the drought here in the southern dessert.

Shown below is a curious fossil Yoav found at our new site in the Matmor Formation we’ve called (creatively) “halfway”. It is a crinoid stem with a pair of skeletal galls, each with several holes. It appears some organisms infected the living crinoid, which then responded by growing skeletal tissue around the offending critters. Eventually the walled-in organisms drilled their way out, leaving the holes. This is what it looks like, anyway. Feel free to speculate!

I’ve placed a slightly different view of the fossil below to show that these are not encrusters but rather echinoderm skeletal material.

We had a great day despite the pervasive dust and wind gusts. It feels so good to get back to a desert again.

Wooster Geologists in southern Israel for Spring Break fieldwork

March 11th, 2012

It’s a low-light, iPad photo, but at least it shows Wooster geology junior Melissa Torma enjoying a fine meal in the Hotel Ramon of Mitzpe Ramon, deep in the Negev of Israel. We arrived here this afternoon after a 22-hour journey from Ohio. The hardest part for me was enduring the 10.5-hour flight and then making a quick transition to driving through heavy Tel Aviv traffic on our southern journey. It all went well, though, and we are safely in our rooms getting ready for our first day of fieldwork tomorrow.

Melissa and I are here to measure sections and collect specimens for her Senior Independent Study project involving the description and paleoecological analysis of a Jurassic brachiopod-crinoid community in the Matmor Formation of Hamakhtesh Hagadol. I’ve collected these crinoids before here, and now Bill Ausich of Ohio State University and I are describing them as a new species of Apiocrinites. Melissa and I want to find more specimens (we hope more complete specimens) of this crinoid and place them in the context of the entire marine community they inhabited. Our partner in this effort is again our friend Yoav Avni of the Geological Survey of Israel.

When we left the USA yesterday there was a series of violent actions between terrorists in Gaza and the Israel Defense Forces. You may hear about rockets from Gaza striking southern Israel, but they are far from us. We see no evidence of the fighting here. We are very safe in the vastness of the Negev Highlands.

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