Return to the Pliocene at Altavilla Milicia, Sicily

June 8th, 2013

9. Altavilla Milicia 060813Our last stop of the day on the IBA field trip was to a classic fossil locality on the north coast of Sicily about an hour east of Palermo. These are fine sandstones and marls preserving a diverse array of mollusks from the Pliocene, including the bivalves shown below. Over 130 bryozoan species have been recorded from this site since 1921. The most interesting features to me were the numerous sclerobionts, including shallow worm and barnacle borings and encrusting bryozoans and barnacles.
10. Altavilla Milicia fossils 060813From here it was a long drive to the beautiful and ancient city of Milazzo to prepare for our last day of the field trip.

Pliocene marls white as snow in southern Sicily

June 6th, 2013

6. Pliocene Cliff 060613SCIACCA, SICILY, ITALY–Our last stop of the day on this International Bryozoology Association pre-conference field trip was to a massive outcrop of foraminiferan-rich marls known as the Trubi. A view of the cliffs with the sun setting behind them is above.

7. Hans Arne Pliocene 060613My colleague (and roommate on this trip) Hans Arne Nakrem is serving as a scale to show the regular cyclicity of these marls. Appropriately, he is from snowy northern Norway. These sediments were deposited immediately after the Messinian Salinity Crisis when the entire Mediterranean was reduced to a shallow series of evaporitive ponds. These marls mark the opening of the Strait of Gibraltar which flooded the Mediterranean Basin with normal seawater (the Zanclean Flood) 5.33 million years ago.

8. Pliocene Cliff 060613I wish I had better lighting to show just how brightly white these rocks are. They are now used as the base type section of the Zanclean Stage.

SicilyBeachSandHere is a late addition to this post (June 23, 2013). I collected some sand from the beach in front of these chalky rocks. A close-up image is shown above. Note that the chalk itself is eroded so quickly that it leaves no trace in the sand. We see here mostly rounded quartz grains and shell fragments.

Wooster’s Fossils of the Week: More bryozoan etchings and an African slug surprise

March 3rd, 2013

CheilostomeEtchings2_585This is the inside of a modern cockle shell (Dinocardium vanhyningi) found on a beach in Wilmington, North Carolina. Across the surface is a radiating series of pits, each of which was formed under a zooid of an encrusting cheilostome bryozoan colony, much like Ropalonaria described last week. This etched shell gives me an opportunity to tell a cautionary tale of trace fossils, slugs and taxonomy.
pdt12291This scanning electron microscope image was taken by my friend and colleague Paul Taylor at The Natural History Museum in London. It shows a cheilostome bryozoan etching (the elongated pits) across a shell surface very much like the modern shell at the top of the page. In the lower right is a bit of the cheilostome bryozoan Amphiblestrum. This particular bryozoan did not make the pits themselves (it is oriented in a different direction), but another colony of the same species likely did. This assemblage comes from the Coralline Crag Formation (Pliocene) exposed in Broom Pit, Suffolk, England.

In 1999, Paul Taylor, Richard Bromley and I published a paper in the journal Palaeontology describing these bryozoan etching pits as a new ichnogenus (a category of trace fossil) with a Late Cretaceous to Holocene range. We invented (or so we thought) the name Leptichnus using the Greek roots leptos (‘flimsy, delicate, subtle’) and ichnos (‘track, footprint’). It was a fun little project, and we provided a useful name to embed this fossil in the literature.

This past fall, thirteen years after publication, I decided to write a Fossil of the Week entry on Leptichnus. In my innocence I searched Google for “Leptichnus” and was very surprised to find it has a Wikipedia page — and it was an East African slug! Yes, the beautiful name Leptichnus was preoccupied by a urocyclid terrestrial gastropod, Leptichnus Simroth, 1896, found in Kenya and Tanzania. 1896 is a long time before 1999, so Simroth’s name has priority over ours. The ichnogenus Leptichnus Taylor, Wilson and Bromley, 1999, thus became a junior homonym of the gastropod genus Leptichnus Simroth, 1896. We had to come up with a new name for it.
LeptichnusOriginalDescription_585 copyAbove is the original 1896 description of Leptichnus The Slug by Heinrich Rudolf Simroth (1851-1917). He apparently came up with the name because this shell-less snail left a subtle trail behind it when it slithered. It is the first time I’ve seen the -ichnus suffix used for anything but a trace fossil.
Heinrich_Simroth_1902Herr Doktor Professor Simroth was a German zoologist and malacologist educated at the University of Leipzig. He was a schoolteacher for his whole career, doing prodigious research in his spare time. His speciality was, unsurprisingly, terrestrial slugs. He worked on specimens brought back by scientific expeditions, including one in the short-lived colony of German East Africa. It is from this collected material he described Leptichnus. Simroth’s type collection was long considered lost, but many specimens were recently rediscovered in Berlin (Glaubrecht, 2010). These do not, alas, include any representatives of Leptichnus. The image above is of Simroth in 1902.

Taylor, Wilson and Bromley (2013) proposed the new name Finichnus to replace Leptichnus Taylor, Wilson and Bromley, 1999. To preserve the meaning of the original name, we substituted the Greek finos (‘fine, delicate’) for leptos.

The lesson of this story? Search, search, search for homonyms of new taxonomic names. In our defense, searching wasn’t as easy back in the 90s (Google’s search engine came online in 2000, for example, and Wikipedia began in 2001). At least the adventure introduced us to Heinrich Rudolf Simroth and his slugs!


Glaubrecht, M. 2010. Slug(-gish) science, or an annotated catalogue of the types of tropical vaginulid and agriolimacid pulmonates (Mollusca, Gastropoda), described by Heinrich Simroth (1851–1917), in the Natural History Museum Berlin. Zoosystematics and Evolution 86: 15–335.

Rosso, A. 2008. Leptichnus tortus isp. nov., a new cheilostome etching and comments on other bryozoan-produced trace fossils. Studi Trentini – Acta Geologica 83: 75–85.

Simroth, H. 1896. Über bekannte und neue Urocycliden. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft 19: 281–312.

Taylor, P.D., Wilson, M.A. and Bromley, R.G. 1999. Leptichnus, a new ichnogenus for etchings made by cheilostome bryozoans into calcareous substrates. Palaeontology 42: 595–604.

Taylor, P.D., Wilson, M.A. and Bromley, R.G. 2013. Finichnus, a new name for the ichnogenus Leptichnus Taylor, Wilson and Bromley, 1999, preoccupied by Leptichnus Simroth, 1896 (Mollusca, Gastropoda). Palaeontology (in press).

Wooster’s Fossil of the Week: A swimming clam from the Pliocene of Cyprus

December 23rd, 2012

In the summer of 1996, I was a co-director of a Keck Geology Consortium project in Cyprus. One of my students was Steve Dornbos (’97), now a professor at the University of Wisconsin, Milwaukee. We had a great time exploring the Nicosia Formation (Pliocene) and its fossils on the Mesaoria Plain near the center of this Mediterranean island. (We published the study — Steve’s Independent Study thesis at Wooster — in 1999.)

One of our most common fossils in the Nicosia Formation is shown above. It is the pectinoid bivalve Amusium cristatum Röding, 1798. It is a remarkably thin and delicate shell that still retains much of its color after over four million years. Note that it is almost completely equilateral, meaning that it is nearly symmetrical. There’s a functional reason for this we’ll get to later.

Amusium is a genus still very much in existence today. They are usually found in abundance on carbonate platforms, often in the deeper portions. They are called “saucer scallops” or “moon shells” by collectors. There are many living species of Amusium, and they are apparently good eating (see below a platter from Thailand).

Both the genus and species of Amusium were named by Peter Friedrich Röding (1767–1846), a German shell specialist from Hamburg. He wrote a 1798 sale catalogue of a mollusk collection, providing the first publication of over 1500 taxonomic names. His descriptions were minimal, but enough to meet the requirements for new taxa, including Amusium cristatum.

Now, what is the functional importance of the symmetry of this particular scallop? Turns out it is one of the best swimmers in the bivalve world. By clapping its valves together with its strong adductor muscle, Amusium can swim at an average of 37-45 cm/second, usually for 8-10 seconds. Symmetry of the shell gives it good control over swimming direction. Features that also enhance the swimming abilities of Amusium include strengthening ribs (visible in our specimen above), a centrally-located adductor muscle, and a mantle that can direct water expulsion during the “clapping” actions of swimming.

We can be certain, then, that Amusium cristatum was a beautiful and unusually active mollusk in those shallow seas that once covered the beautiful island of Cyprus.


Aguirre, J. 2009. Biological concentrations of Amusium cristatum. Journal of Taphonomy 2-3: 263-264.

Dornbos, S.Q. and Wilson, M.A. 1999. Paleoecology of a Pliocene coral reef in Cyprus: Recovery of a marine community from the Messinian Salinity Crisis. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 213: 103-118.

Morton, B. 1980. Swimming in Amusium pleuronectes (Bivalvia: Pectinidae). Journal of Zoology 190: 1469-7998.

Röding, P.F. 1798. Museum Boltenianum sive catalogus cimeliorum e tribus regnis naturæ quæ olim collegerat Joa. Fried Bolten, M.D. p. d. per XL. annos proto physicus Hamburgensis. Pars secunda continens conchylia sive testacea univalvia, bivalvia & multivalvia. – pp. [1-3], [1-8], 1-199. Hamburgi, Trapp.

Williams, M.J. and Dredge, M.C.L. 1981. Growth of the saucer scallop, Amusium japonicum balloti Habe, in central eastern Queensland. Australian Journal of Marine and Freshwater Research 32: 657–666.

Wooster’s Fossils of the Week: Corkscrew shells from the Pliocene of Cyprus

May 20th, 2012

Steve Dornbos (’97), now a professor at the University of Wisconsin, Milwaukee, and I found these intricate shells by the hundreds in the Nicosia Formation (Pliocene) of Cyprus during his Independent Study field work. (We published this study in 1999.) They are the gastropod (snail) species Turritella tricarinata (Brocchi 1814).

Turritellid snails are still very common today, so we know quite a lot about their ecology and physiology. They are an unusual mix of deposit-feeder and filter-feeder, eating organic particles on the sediment surface and in the water. They do it by creating a current with cilia, drawing water into their mantle cavities. There they have a complex system of tentacles that filter out the largest particles, allowing only the small, digestible goodies onto the surfaces of their gills. The organics are coated with mucus and made into a kind of sticky string that is pulled into the mouth (Graham, 1938). These snails are usually found in large aggregations, just like what we found in the Pliocene of Cyprus.
Turritella tricarinata was originally described by Giovanni Battista Brocchi in 1814 as Turbo tricarinata. Brocchi (1772-1826) was an Italian natural historian who made significant contributions to botany, paleontology, mineralogy and general geology. He was born in Bassano del Grappa, Italy, and studied law at the University of Padova. He liked mineralogy and plants much better than lawyering, though, and became a professor in Brescia. His work resulted in an appointment as Inspector of Mines in the new kingdom of Italy.

Brocchi wrote the first thorough geological assessment of the Apennine Mountains, and he included in it a remarkable systematic study of Neogene fossils. He compared these fossils to modern animals in the Mediterranean — a very progressive thing to do at the time.
Above are drawings made by Brocchi of the turritellid fossils he found in the Apennines during his extensive study published in 1814. Note that in the Continental fashion still followed today, the shells are figured aperture-up. Americans and the rest of the English-speaking world orient them in the proper way.

Brocchi was an adventurous traveler, but it eventually did him in. He died in Khartoum in 1826, a “victim of the climate” and a martyr for field science.


Brocchi, G.B. 1814. Conchiologia fossile subapennina con osservazioni geologiche sugli Apennini e sul suolo adiacente. Milano Vol. I: pp. LXXX + 56 + 240; Vol. II, p. 241-712, pl. 1-16.

Dornbos, S.Q. and Wilson, M.A. 1999. Paleoecology of a Pliocene coral reef in Cyprus: Recovery of a marine community from the Messinian Salinity Crisis. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 213: 103-118.

Graham, A. 1938. On a ciliary process of food-collecting in the gastropod Turritella communis Risso. Proceedings of the Zoological Society of London A108: 453–463.

Wooster’s Fossil of the Week: an Italian keyhole limpet (Pliocene of Cyprus)

November 6th, 2011

This week’s fossil is a beautiful little gastropod (snail) scientifically known as Diodora italica (Defrance, 1820), and commonly as the Italian Keyhole Limpet. I collected it with Steve Dornbos (’97) during the 1996 Keck Geology Expedition to Cyprus, where it was part of Steve’s Independent Study project describing a Pliocene reef.
Diodora italica belongs to the Family Fissurellidae and is not a “true limpet”. The hole at the top gives it away as something different than the usual simple cap-like limpet shell. Several gastropod groups have evolutionarily converged on the flat shell because it is efficient at withstanding the stresses of strong waves and, curiously, the high pressures in the deep sea. Diodora is still alive, as you can see in this nice (and copyrighted) image.

The hole at the top of the shell, the “keyhole”, is part of the respiration system of these snails. They take in water under the edge of the shell, pass it over a pair of gills, and then send the used water out the “chimney” of the keyhole.

Keyhole limpets scrape algae and bacteria from rock surfaces, using the strong foot to adhere to the substrate

Diodora italica was described by the oh-so-French naturalist and collector Jacques Louis Marin Defrance (1758-1850). I can’t find much about him, but there is a nice portrait!


McLean, J.H. 1984. Shell reduction and loss in fissurellids: a review of genera and species in the Fissurellidae group. American Malacological Bulletin 2: 21–34.

Murdock, G.R. and Vogel, S. 1978. Hydrodynamic induction of water flow through a keyhole limpet (Gastropoda, Fissurellidae). Comparative Biochemistry and Physiology Part A: Physiology 61(2): 227–231.

Wooster’s Fossil of the Week: Pelican’s-foot snail (Pliocene of Cyprus)

July 17th, 2011

This week’s fossil was found on the same 1996 Keck Geology Expedition to Cyprus that produced the Thorny Oyster highlighted in January. Stephen Dornbos (’97) was there, but this fossil was not part of the Pliocene coral reef complex he and I described (Dornbos & Wilson, 1999), but it was in nearby shallow marine embayment muddy sediments.

The pelican’s-foot snail is Aporrhais pespelecani (Linnaeus, 1758). It got its common name before Linnaeus because of its resemblance to a pelican’s webbed foot. When the snail reached a mature size, it extended the outer lip of its aperture into spines as an anti-predatory defense (probably against crabs) and as possibly a way to spread its weight (“footprint”, if you like) on soft sediment.

A. pespelecani belongs to the Superfamily Stromboidea, a very large group that includes familiar snails like the true conch (Strombus). A recent morphological analysis suggests they are also related to the carrier shells (Xenophoridae), although genomic sequencing is needed for support (Simone, 2005).

The pelican’s-foot snail lives today in the eastern Atlantic as well as the Baltic, Black and Mediterranean seas. It is a carnivore on clams and has the ability to “flick” its muscular foot to escape predators.

These distinctive shells have been known in Europe for a very long time. I like this particular illustration by Niccolò Gualtieri (1688–1744) in which they appear to be dancing:

As is often the case with writing these little essays, I learned something about a brilliant scientist now almost forgotten. Niccolò Gualtieri was a Florentine polymath skilled in medicine, poetry, drawing, and the developing natural sciences. He had his own shell museum, so he can be said to be one of the first conchologists.

I’m sure we shared Gualtieri’s delight when we first saw these distinctive shells scattered across a dry Cypriot plain.


Dornbos, S.Q. and Wilson, M.A. 1999. Paleoecology of a Pliocene coral reef in Cyprus: Recovery of a marine community from the Messinian Salinity Crisis. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 213: 103-118.

Gualtieri, N. 1742. Index Testarum Conchyliorum, quae adservantur in Museo Nicolai Gualtieri (“List of the shells of shellfish which are preserved in the museum of Niccolò Gualtieri”).

Manganelli, G. and Benocci, A. 2011. Niccolò Gualtieri (1688–1744): biographical sketch of a pioneer of conchology. Archives of Natural History 38: 174-177.

Simone, L.R.L. 2005. Comparative morphological study of representatives of the three families of Stromboidea and the Xenophoroidea (Mollusca, Caenogastropoda), with an assessment of their phylogeny. Arquivos de Zoologia 37: 141–267.

Wooster’s Fossil of the Week: The Multidisciplinary European Thorny Oyster (Pliocene of Cyprus)

January 30th, 2011

In the summer of 1996, I was a co-director of  a Keck Geology Consortium project on the island of Cyprus. My students and I worked on the hot central plains far from the well known ophiolite complex in the cool mountains. One day Wooster student Steve Dornbos and I stumbled across a fantastic coral reef weathering out of Pliocene silts and clays. (Check out the locality on Google Maps at N35° 5.767′, E33° 8.925′. We weren’t far from the UN Buffer Zone between us and the “Turkish Cypriot political entity” to the north.) Describing this fossil reef and its associated organisms, and interpreting it as a recovery fauna after the Messinian Salinity Crisis, became the basis of Steve’s Independent Study. I like to think it is what made him the famous paleontologist he is today.

The reef framework was made by the scleractinian coral Cladocora, and there was a wonderful diversity of other organisms preserved in and on its branches. (You can read our paper about the reef by downloading this pdf: Dornbos & Wilson, 1999.) One of the most spectacular is shown above: the European Thorny Oyster Spondylus gaederopus Linnaeus 1758. This filter-feeding pectinoid bivalve (not a true oyster) cemented itself to the coral and then filtered the surrounding water for nutrients. It had long spines on both valves, most of which are broken off in our specimen. The exterior of this bivalve is composed of resistant, long-lasting calcite; the interior of shiny, less resistant aragonite.

Spondylus gaederopus has been well known in Europe for at least 5000 years. Its thick shell and mix of calcite and aragonite made it ideal for carving beads, bracelets, rings and other cultural items. The shells were harvested in the Mediterranean and then traded throughout the continent. (Here is the outline of a 2007 European Association of Archaeologists meeting devoted just to Spondylus.) This species was one of the first bivalves named by the famous Swedish taxonomist Carl Linnaeus, and it was cited by Charles Lyell as an important species for sorting out Tertiary and Quaternary geologic time divisions.

Today the versatile shell of Spondylus gaederopus serves another purpose: helping track annual fluctuations in sea surface temperatures and salinities in the Mediterranean. These animals were long-lived and their thick shells preserve isotopes of calcium and oxygen from past seawater.

The species has lasted over 23 million years from the Early Miocene until today. I wish I could show you an image of a living Spondylus gaederopus, but the only public domain photographs available are of the related species Spondylus varians from East Timor:

In life the animal has creepy rows of eyes in its colorful mantle around the edge of the shell. For a bivalve it has a rather advanced nervous system, complete with optic lobes for the eyes.

So here’s to the multidisciplinary Spondylus gaederopus who has been in our service from Neolithic times to today. We can even say this particular specimen helped launch a paleontological career.

« Prev