Mode of life of some Silurian and Devonian platyceratids


Authors: Horný RJ

Published in: Bulletin of Geosciences, volume 75, issue 2; pages: 135 - 143;

Keywords: Platyceratid gastropods, Platyceras, Orthonychia, stationary mode of life, empty shells of orthoconic nautiloids, morphology of aperture, Silurian, Devonian, Barrandian area, Bohemia,

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The Silurian and Devonian platyceratid gastropods, by Knight et al. 1960 classified as subgenera Platyceras (Platyceras) and Platyceras (Orthonychia) were adapted not only to a stationary life on crinoid calices, but demonstrably lived also on various firm objects lying at the sediment surface. According to the morphology of aperture, these platyceratid gastropods were not selective in choosing their 'host'; some of them belonged to the community using empty shells of orthoconic nautiloids lying on the sediment surface, others probably inhabited fragments of crinoids, shells of brachiopods etc. or perhaps even lithified parts of bioclastic sediment. These small platyceratids, of course, were not coprophagous but probably either deposit or filter feeders. Unique finds demonstrate a shell with the aperture partly embracing an orthocone or showing its morphology reflected by the gastropod growth structures. The stationary mode of life influenced the withdrawal function and location of the main retractor, the attachment area of which was shifted adaperturally and dorsally to the shell centre of gravity. The research has been carried out on the material from the Barrandian area, Bohemia.