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.

References:

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!


References:

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.

References:

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.

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