Archive for October 28th, 2016

Wooster’s Fossil of the Week: A naticid gastropod from the Pliocene of southern California

October 28th, 2016

polinices-galianor-sd-pliocene-1-copyThis week’s fossil comes from our teaching collection. It’s label appears to be from the late 19th Century. It is a naticid gastropod (“moon snail“) listed as Polinices galianor. That name, which I can only find in two lists and never with an author, may be a corruption of Polinices (Euspira) galianoi Dall 1909. It was collected from the Pliocene of San Diego County, California. It is preserved as both an internal mold and thin sheets of remnant original shell.

polinices-galianor-sd-pliocene-2-copyThis is a view of the underside along the axis of coiling. The hole is known as the umbilicus and is distinctive for the naticids. These snails are predatory, moving through loose sand with a very large foot and capturing shelled prey, like clams and other gastropods. They then drill a beveled hold through the shell of the prey with specialized teeth in their radulae. We’ve discussed the trace fossils they leave (Oichnus) in a previous post.

The genus Polinices was named in 1810 by Pierre Dénys de Montfort (1766–1820), a French malacologist (one who studies mollusks).

screen-shot-2016-10-22-at-11-52-46-amThe title page of de Monfort (1810).

screen-shot-2016-10-22-at-11-49-26-amThis brief paragraph is all it took in the early 19th Century to name a new taxon. The system is much more elaborate now.screen-shot-2016-10-22-at-8-20-44-pmPierre Dénys de Montfort is a tragic figure in science. First, he had the misfortune of being a French intellectual during the chaos of the French Revolution and the resulting Napoleonic dictatorship. Scientists struggled then, but after service in the revolutionary army and an apprenticeship with a geologist, de Monfort gained a position in the Jardin des Plantes, a research botanical garden in Paris. He did a massive study of mollusks, producing systematic tomes. De Monfort was a whiz at languages, so he did well as a translator after Napoleon was  finally defeated in 1815 and the Allied armies occupied Paris. Then he went off the rails. He had since 1801 championed the reports of mariners that giant cephalopods occasionally rose from the sea and attacked shipping, as shown in his above print (de Monfort, 1801, p. 256). The modern roots of the kraken! De Monfort took the idea too far, was ridiculed in the scientific community, and eventually died of starvation and alcoholism in the streets of Paris in 1820. The later discovery of giant squid salvaged his reputation a bit, but no one has yet found evidence of “le poulpe colossal”.


Dall, W.H. 1909. Contributions to the Tertiary paleontology of the Pacific coast. U.S. Geological Survey Professional Paper 59. U.S. Government Printing Office, 288 pages.

de Montfort, P.D. 1801. Histoire naturelle, générale et particuliere des Mollusques, animaux sans vertèbres et á sang blanc. Volume 2. Paris, 424 pages.

de Montfort, P.D. 1810. Conchyliologie systématique, et classification méthodique de coquilles. Volume 2. Paris, 692 pages.