Wooster’s Fossil of the Week: A mytilid bivalve from the Middle Jurassic of southern Israel

August 5th, 2016

1 Mytilus (Falcimytilus) jurensis 585This week’s specimen comes from one of my favorite fossiliferous units: the Matmor Formation (Middle Jurassic, Callovian) of Makhtesh Gadol in southern Israel. I’ve been delighted by the fossils and lithologies of the Matmor since 2003. This particular fossil is exposed in a bedding plane of the very rich subunit 65, which I’ve mentioned before in this blog. It is a mytilid bivalve identified as Mytilus (Falcimytilus) jurensis It has the classic wing shape of its order.
2 Mytilus (Falcimytilus) jurensisM. jurensis is very common in the Matmor Formation, especially in the upper third where it can be seen protruding from limestones at a variety of angles. The species was widespread throughout the Tethys Ocean, now recorded by sediments in the Middle East and Mediterranean regions.
3 mytilids090809Mytilid bivalves are very common today as well, and they have the same life mode as they did at least 150 million years ago. They attach to hard substrates in shallow waters with strong fibers they secrete called byssal threads. Above we see our M. jurensis shell with several others clustered around a gastropod shell to which they were attached. The organic byssal threads are long gone, of course, but the shells remain in their living positions.

I like to use these Fossils of the Week to explore their taxonomic histories. The specimens, after all, are usually not exceptionally well preserved or rare, but they all have stories. Mytilus (Falcimytilus) jurensis proved to be a challenge when it came to identifying the author of the species.
4 MNHN figFirst I went to the online catalogue of the Muséum National D’Histoire Naturelle in Paris — an excellent resource. There I found the above image and information. Someone named Roemer named the species in 1836. So who was this Roemer and what was the publication?
5 Friedrich Adolph RoemerAfter considerable searching, I learned our taxonomist was Friedrich Adolph Roemer (1809-1869), a German geologist born in Hildesheim, part of the Kingdom of Westphalia. He had a younger brother, Carl Ferdinand von Roemer, who was also a geologist, creating some confusion.
6 Oolithen-GebrigesFriedrich Roemer has an 1836 book (above) that roughly translates as The Fossils of the North German Oolitic Mountains, “oolitic” referring to a kind of limestone common in the European Jurassic; for awhile it was essentially synonymous with “Jurassic”.
7 Plate IV, fig 10On Plate IV, fig. 10, of this 1836 book is a pair of drawings of Mytilus jurensis. So far all is on track for sorting out the taxonomic history of the species.
8 p 89Surprise! When we look at the description in the text on page 89, we see that Roemer gives an undated credit for the species to “Merain”. Who is Merain?
9 Thurmann p 13I thought I’d never find the identity of this “Merain”, but through the extraordinary resource of Google Books, I uncovered the earliest record of Mytilus jurensis. It is on page 13 of Thurmann (1833). Note that following the species (fourth line above) is “Mèr.” and then “n. sp.”, meaning “new species”. (I have no idea what the intervening “M. Bas.” indicates. [Update: See comment by Christopher Taylor below.]) There is no description of the species, and no illustration, but there’s the first mention of it.

So is “Mèr.” short for Roemer’s “Merain”? Turns out Roemer misspelled the last three letters — it is “Merian”.
10 Peter_MerianPeter Merian (1795-1883) was a Swiss geologist and paleontologist who was born in Basel. He studied scientific topics at the University of Basel, the Academy of Geneva, and the University of Gottingen. After two years in Paris, Merian returned to Baasel and began to specialize in the geology and fossils of the Jura Mountains. He was appointed a professor of physics and chemistry at the University of Basel, and later an honorary professor of geology and paleontology. He was also Director of the Natural History Museum in Basel. Along with his work on Triassic and Jurassic fossils, he also made contributions to glaciology and meteorology. Peter Merian died in Basel in 1883 after a long, notable career. He certainly looked the part of a dashing 19th Century Swiss geologist. Kevin McNally could play him in the movie! And now we know that he was the man who named Mytilus jurensis in 1833. Roemer (1836) was probably credited with the species at one point because he had the first description and figures. Merian, apparently, just provided the name in someone else’s book.
11 Merian map JuraHere is an 1829 geological map by Peter Merian of a portion of the Jura Mountains, one of the first of the region.


Cox, L.R. 1937. Notes on Jurassic Lamelibranchia V. On a new subgenus of Mytilus and a new Mytilus-like genus. Journal of Molluscan Studies 22: 339-348.

Freneix, S. 1965 – Les Bivalves du Jurassique moyen et supérieur du Sahara tunisien (Arcacea, Pteriacea, Pectinacea, Ostreacea, Mytilacea). Annales de Paléontologie, t. 51, vol. 1, p. 51-113.

Liu, C. 1995. Jurassic bivalve palaeobiogeography of the Proto-Atlantic and application of multivariate analysis method to palaeobiogeography. Beringeria 16: 31123.

Liu, C., Heinze, M. and Fürsich, F.T. 1998. Bivalve provinces in the Proto-Atlantic and along the southern margin of the Tethys in the Jurassic. Palaeogeography, Palaeoclimatology, Palaeoecology 137: 127-151.

Merian, P. 1829. Geognostischer Durchschnitt durch das Jura-Gebirge von Basel bis Kestenholz bey Aarwangen, mit Bemerkungen über den Schichtenbau des Jura im Allgemeinen. Zürich.

Roemer, F.A. 1836. Die Versteinerungen des Nordeutschen Oolithen-Gebirges. Hahn. 218 pages.

Thurmann, J. 1833. Essai sur les soulèvemens Jurassiques du Porrentruy, avec une description géognostique des terrains secondaires de ce pays, et des considérations générales sur les chaines du Jura. Mém. Soc. Hist. Nat. Strasbourg 1: l-84.

A Wooster Geologist visits the caves of Tel Maresha in central Israel

March 21st, 2016

1 Bell caves MareshaTEL AVIV, ISRAEL — My last day in Israel was spent with my friend Yoav Avni exploring some sites in the central part of the country before my flight left Tel Aviv late in the evening. The most geological place we visited was Maresha (which later became, in order, Beit Guvrin, Eleutheropolis, Bethgibelin, Bayt Jibrin, Kibbutz Beit Guvrin and Beit Guvrin National Park — you know there’s a long story there!). Maresha was an 8th Century BCE Israelite city in Judah that guarded several trade routes and access to the Judean hills from the coast. It thus had significant strategic value and was subject to just about every conqueror of the region since the Iron Age. The bedrock has a very thick section of the Maresha Formation (Eocene), a homogeneous soft chalk that is easily carved. This chalk has long been quarried for building stone and the main component of plaster and cement. The typical quarries are bell-shaped, with a small circular entrance from ground level and an expanding cone downwards. Above we see several intersecting quarries exposed by a roof collapse.

2 Bell caves signHere is a helpful diagram showing the construction of bell caves. The top geological layer is a hard calcrete (caliche) locally called nari. It provides a strong roof for the quarries.

3 Bell cave openingThe opening of a bell cave through the calcrete upper layer.

4 Bell cave carving marksThe sides of the quarries easily show the tool marks made by the workers as they spiraled down into the bedrock. This rock is soft enough to dig with your fingernails.

5 Columbarium Maresha

Residents of Maresha, especially in the diverse Hellenistic times (2nd-3rd centuries BCE), reused the quarries for living and working spaces, expanding several into new rooms. Above Yoav is standing in the largest columbarium, a place to raise doves for food and rituals. (Not for the storage of ancestral ashes or bones, as was once thought.)

6 Yoav in Columbarium MareshaI didn’t want to crop out Yoav’s happy face! He is standing in the bottom of a bell cave repurposed as a columbarium.

7 Olive cracker MareshaThere are several underground olive oil factories that were active from the 3rd Century BCE until modern times. This device was driven by a donkey to crush raw olives.

8 Large olive press MareshaThis is an underground olive press. Heavy stones were attached to the beams to press the juices out of olives cracked first by the donkey apparatus above.

9 Siddonian cavesThe Sidonian tombs (about 2nd Century BCE) are very impressive. All the carving is original, but the paint shown above is a modern reconstruction. This inscription on a tomb here is haunting:

Nothing else remains that I can do for you, or that will pleasure you. I am sleeping with someone else, but it is you I love, dearest to me of all.

In the name of Aphrodite, I am happy about one thing, that your cloak has been left to me as a pledge.

But I flee, and permit you expanses of freedom. Do anything you desire.

Do not strike the wall; it only makes noise. We will motion to each other; this will be the sign between us.

10 Maresha countrysideThe scenery above ground at Tel Maresha is lush and green. This region received more than the usual amount of rain this season, and it shows. We are looking here from the tel towards Hebron in the Judean hills. Note the herd of sheep in the middle ground distance.

11 Bedouin sheep MareshaLater in the day we met those sheep and their Bedouin shepherds.

12 Tel MareshaAnd here is Tel Maresha itself. Only 10% has been excavated, so much more remains to be discovered.


My tradition at the end of a field excursion is to include my most important GPS numbers and coordinates:

125: N29.99183°, E35.07680° Gerofit Junction Ora Formation
126: N30.94310°, E34.97972° SU62 below oolite; nice corals
127: N30.94323°, E34.99110° Top Zohar Cliff
128: N30.95774°, E35.00615° SU65 bedding plane
129: N30.94358°, E34.97828° SU65 in Matmor Hills
130: N30.94812°, E35.00099° Lowest exposed Zohar
131: N30.33491°, E34.92828° Road to Be’er Ada
132: N30.32229°, E34.90701° Be’er Ada
133: N30.32553°, E34.90683° Near Be’er Ada along fault
135: N30.32973°, E34.91417° Ada Canyon top view
136: N30.32001°, E34.97467° Wadi Paran cliffs

Wildflowers of the Negev, 2016 version

March 21st, 2016

1 purple flower 031616MITZPE RAMON, ISRAEL — One of my last posts from a trip into the Negev is a selection of flower images. (Here is the previous wildflower post. None of the blooms are the same.) I don’t know any of their names, so I depend on commentators to help me add them. Above is a nice purple flower from Makhtesh Ramon.

2 Light purple flowersAnother purple flower, this one with four petals. Makhtesh Ramon.

3 Flower with two insectsThis swirly purple flower has two insects on it. Did one arrive to eat the other? Makhtesh Gadol.

4 Blood red flowersThese blood-red flowers are on a common shrub in the wadis.

5 Red flowersThese flowers of unusual shape are very common in all the wadis I visited.

6 Spiky bubbles bushA spiky bubble bush in Makhtesh Gadol.

7 Spiky bubbles closeA closer view of the spiky bubble bush. I was told that squeezing the bubbles produces a foul smell. I did not experiment.

8 Wrapped thistleThese thistle-like plants are always wrapped in some sort of insect or spider silk.

It was a beautiful season for flower diversity, if not abundance. Comments welcome!

Last day of fieldwork in Israel: More Jurassic enjoyment

March 20th, 2016

1 SU66 at Meredith 032016MITZPE RAMON, ISRAEL — For my last day of fieldwork during this short Spring Break trip to Israel, I returned to Makhtesh Gadol to collect a bit more data from subunits 65 and 66 of the Matmor Formation (Middle Jurassic, Callovian). The above image shows part of my field site in the Meredith section north of the “British Road” across the top of the makhtesh. The yellowish marls are subunit 66, with the white limestone of subunit 65 peeking out at their base. The Matmor Formation is distinguished by this alternation of carbonates and marls, and the faunas in each sediment type are very different.

2 SU65 bivalve at Meredith 032016I did not do any collecting today. Most of my work was tracing rock units, photographing fossils, and taking lots of notes. Above is a nice bivalve in the limestone of subunit 65.

3 SU65 bivalve and bullet 032016Here’s another bivalve with a spent bullet for scale. (Dramatic effect. There is far less ordnance in Makhtesh Gadol than other places I’ve worked in the Negev.) Note that the bivalve is articulated (both valves are locked together), meaning it likely was buried alive. Almost all the bivalves in subunit 65 are articulated.

4 SU65 branching coral 032016There is one horizon in subunit 65 with a surprising number of branching corals. These look very much like the modern Acropora, but they’re not.

5 SU65 SU66 boundary at Meredith 032016This is again the boundary between the white and resistant subunit 65 and the yellowish and nonresistant subunit 66. I have no images of fossils to show you from subunit 66 because they weren’t very photogenic. They are relatively rare and consist mostly of small solitary and colonial corals and occasional oysters.

Thus ends my 2016 fieldwork in Israel! I learned a lot in these eight days of exploration and study, and I worked with excellent colleagues. I have some ideas now for a project that will place these Middle Jurassic rocks and fossils in a global paleobiogeographic and evolutionary context. Many future Independent Study projects are possible!

My neighborhood in Mitzpe Ramon, southern Israel

March 20th, 2016

1 My street MR 032016MITZPE RAMON, ISRAEL — Some images from the little town in the Negev where I spend my nights. I like being based here because my students and I are central to all of our diverse geological localities. It is also my friend Yoav Avni’s home. Plus, it reminds me of my hometown of Barstow, California, in its desert setting, diverse population, and edge-of-civilization feeling. (The architecture, though, is not at all the same!)

Hotel MR 031916I stay in the Ramon Suites hotel, which is very comfortable and reasonably priced. It is a short walk from here to the edge of Makhtesh Ramon.

2 Brooklyn house MR 032016Near the hotel is a building from Brooklyn! This is a Chabad-Lubavitch house. I’ll let this link to 770 Eastern Parkway begin the explanation. There are replicas of this house all over the world, each with the number 770.

3 Edge of town MR 032016The southwestern edge of town, with a new school and synagogue. The edge of the makhtesh is a few meters beyond the conical hill.

4 Skyline with New Hotel MROn the top of the skyline is a very fancy hotel well beyond my means. It looks cool, and strangely ancient.

5 Skyline with Makhtesh MR 032016A view to the southeast showing a wall of the makhtesh in the far background.

6 Water tower MR 032016The iconic Mitzpe Ramon water tower, visible for many kilometers. It is the most interesting thing I can see from my hotel room.

7 Childrens mural MR 032016A children’s mural on the outside of a school. Note the water tower on the left, the desert wildlife, and even a dinosaur. (No dinosaurs have been found here, alas.) This children’s view of their dry town is strangely watery.

8 Grocery store MR 032016Last and least, the town’s grocery store. Crowded and unfriendly. Always feels a bit Soviet to me, probably because as in that regime there was little choice where to shop. Still, they have kept me and my students supplied.

A geological obstacle course in Ada Canyon, southern Israel

March 19th, 2016

1 Ada canyon startMITZPE RAMON, ISRAEL — As part of our Shabbat trip today, Yoav Avni wanted to take me up Ada Canyon (N30.32973°, E34.91417°) to explore the Hazeva (Miocene) and Arava (Pleistocene). He cryptically said, “There will be places we can barely get through”. True, that. Above is Yoav at the start of the hike. Turns out this is a slot canyon with challenges.

2 Arava narrows begin“The narrow part begins”, he says helpfully.

3 Narrowing AravaAt this point I have to take off my pack to reduce my sideways width.

4 Narrow AravaAnd sideways with a twist is the only way through as the walls close in. Pro tip: Never do this when it is raining.

5 Problematic Arava sectionNow it gets problematic with boulder scrambling and claustrophobia.

6 First ladder aravaA ladder! I never did mention my aching shoulder.

7 Second ladder AravaSteps cut in the rock and then a second ladder. Going down is always easier than going up, right?

8 Rope climb AravaA knotted rope to climb the cliff! Note the shadow of successful me at the top of the last obstacle. Wondering, though, what these climbs are like on the way back.

9 Ada view 031916The view at the top of the mountain, though, really was spectacular. This is a view towards Be’er Ada, with the fault described in the previous post running diagonally across the background.

10 Hazeva cobbles 585And yes, the geology along the way! It was very impressive. The Hazeva Formation is mostly sandstone with some layers of sandy conglomerate as in the above image. It was deposited in a wetlands with occasional floods (which produced the coarse layers). The cobbles are rounded cherts derived from Jordan to the east.

11 Arava faciesThe Arava Formation was deposited in a desert much like what we see today. It is interbedded gravels (from wadis) and unconsolidated silts (from playas and saline lakes). Classic sed/strat material. It was all well worth the adventure for this aging geologist!


A Shabbat trip to Be’er Ada in the southern Negev

March 19th, 2016

1 Road to Beer AdaMITZPE RAMON, ISRAEL — Yoav Avni and I have a tradition on Shabbat. We drive somewhere to explore interesting geology and history unconnected to current projects. It’s not really work — it’s geotourism. We are, though, always talking about new ideas. Today we traveled south of Mitzpe Ramon into the “deep desert” of the Arava below the Negev Highlands.

2 MR view to JordanThe morning view south across Makhtesh Ramon was spectacular. It isn’t conveyed very well through an image only 585 pixels wide, but it is a perspective of unusual clarity. The purple streak at the top represents mountains in western Jordan. The haze just below them is in the Arava Valley. We are looking across most of the Negev.

3 Acacia grove Beer AdaOur mission today was to visit Be’er Ada (Bir Abu ‘Auda), an historic well, and the geology around it. (N30.32229°, E34.90701°, if you’re following at home.) The top image on this post is a view from the road to the well. Just above is a grove of acacia trees near the well. The abundance of these trees, and their good health, is an indication of accessible water.

4 Yoav at Beer AdaHere is Yoav peering down into Be’er Ada. (“Be’er” means well.) It is at least twenty meters deep. The base is filled with silt, so it will have to be dug out to supply water again. This well is thousands of years old and has been a critical watering spot in the Negev for traveling groups. The next nearest well is to the east about 40 km away. Another 40 km or so to the west is another well. Be’er Ada was active as late as the 1950s, and likely had sporadic use afterwards. The water here accumulates on the impermeable clays of the Taqiya Formation (Paleocene).

5 Acacia outcrop view 031916This is a view from near Be’er Ada to the main geological interest for me: the the orangish Hazeva Formation (Miocene) topped unconformably by the gray Pleistocene Arava Formation. We will spend much more intimate time with these units in the next post. Note the graceful acacia trees.

6 Beer Ada faultThis area is next to a complex fault system. On the left is a down-dropped block of Hazeva and Arava, with Cretaceous rocks on the right. The fault is also part of the reason for the subterranean water resources at Be’er Ada.

7 Ada profileIn the middle of the image is an example of the pareidolia so common in stark landscapes. Some people see a face in profile. Apparently tour guides like to call this the head of “Ada” for whom the well was named. However, there never was such a woman!

Note the excellent weather in these images. A perfect Negev day! Thank you to Yoav for being such a generous host.

Wooster’s Fossils of the Week: A Jurassic seafloor assemblage

March 18th, 2016

1 DSC_0184 copyImages from fieldwork this week. These are all fossils exposed on a single bedding plane in the Matmor Formation (Middle Jurassic, Callovian) exposed in Makhtesh Gadol. I found them many years ago while working through the stratigraphy near the top of the formation. They present a vignette of life in a shallow carbonate Jurassic sea. They are so well preserved you can almost feel the gentle waves and hear the squawks of the pterosaurs wheeling above. In the top image we have my favorite of the set: A gastropod shell in the middle surrounded by mytilid bivalves. The bivalves were no doubt attached to the gastropod by their thin byssal threads, holding them in place in the choppy waters. The preservation is remarkable. All these shells are calcitized, but retain their ornamentation. They are exposed on a bank of a wadi, and so they have been lightly etched from the matrix by sandy water during floods.

2 DSC_0180 copyJust to show the gastropod-bivalve association is not a fluke of preservation, here’s another set. On this bedding plane are four such assemblages.

3 DSC_0178 copyHere’s another gastropod, this one with heavy spines.

4 DSC_0179 copyA high-spired gastropod is on the left, with a mytilid in side-view on the right.

5 DSC_0181 copyAnother gastropod to end the set. These are just a few of the many such fossils exposed on this bedding plane of the Matmor Formation.

Exploring the top of the Matmor Formation (Middle Jurassic) in Makhtesh Gadol

March 16th, 2016

1 SU65 south view 031616MITZPE RAMON, ISRAEL — Today I joined four Israeli colleagues to study in detail the top of the Matmor Formation (Callovian, Middle Jurassic) in Makhtesh Gadol, Negev Highlands, southern Israel. The view above is looking south in the Matmor Hills along this upper section. You can see why this kind of exposure is popular with geologists. I love to be able to walk along a single rock unit for kilometers, noting its changes and the distribution of its fossils.

2 Field start 031616Our party consisted of the two Yaels (Edelman-Furstenberg and Leshno), Rivka Rabinovich from Hebrew University and the National Natural History Collections, and her undergraduate student Or Eliasson. We started along the Goldberg section and worked our way up the formation.

3 Quadrat group 031616We concentrated on getting Yael Leshno’s PhD dissertation data collection methods established. Here she sits (in the green scarf) with her advisors Rivka Rabinovich on the left and Yael Edelman-Furstenberg on the right. They are gathering data from a quadrat in Subunit 65 of the Matmor.

4 SU65 view 031616This particular subunit (a term and designation from Goldberg, 1963) is of particular importance to us because it is exposed in the north of the makhtesh as a spectacularly fossiliferous bedding plane. Here we see the same fossils, but they are fully embedded in the calcareous matrix. Or is the young man above searching for fossils, a task he is very good at.

5 Field end of day 031616That was basically our day! The weather was better, with less wind (although still plenty) and far less dust.

A day in the Zohar and Matmor Formations of the Negev

March 15th, 2016

1 Zohar outcrop 031516MITZPE RAMON, ISRAEL — It was another very windy day in southern Israel, but still just fine for fieldwork. Yael Edelman-Furstenburg, Yael Leshno and I returned to Makhtesh Gadol to work on Yael Leshno’s data collection procedures for her PhD project in the Middle Jurassic sequence here. Our first task was figuring out the detailed stratigraphy, which is not especially easy considering all the faulting and somewhat dated lithological descriptions for orientation. The above image is of the Zohar Formation just below its contact with the Kidod Formation (depending on what stratigraphic scheme you follow!).

2 Zohar disconformityThe top few meters of the Zohar Formation are a series of argillaceous limestones with numerous trace fossils (Planolites and Thalassinoides, mainly) and this gorgeous erosion surface (disconformity). The white limestone beneath was lithified when it was exposed and downcut by sand-bearing currents. On the left you can see pieces of the limestone incorporated into the overlying calcareous sandstone. Classic.

3 Goldberg trench 031516We then moved up section into the Kidod Formation (or upper Zohar!) to the site of the first stratigraphic column constructed through these rocks. Right of center you can see a trench dug into the marls by Moshe Goldberg in 1962. This was part of his project to describe the entire Jurassic section in Makhtesh Gadol. We still use his iconic work today as “Goldberg, 1963”.

4 Quadrat start 031516Here are the Yaels starting the very first quadrat measurements within the Matmor Formation. Within a half-meter square they are counting and identifying all the fossils — every little bit over a few millimeters. Student Yael has many of these quadrats in her future!

5 Makhtesh view 031516Here is a view of the Makhtesh with the Yaels at work. You can see our white field vehicle from the Geological Survey in the middle distance.

6 Matmor bedding plane 031516We ended the day at this bedding plane in the upper Matmor Formation I remembered finding many years ago. It has spectacular clam and gastropod fossils across its surface, many in apparent life positions. I’d show you images of the critters, but I’m saving them for a Fossil of the Week post!


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