Interesting borings

Stephen K Donovan (The Netherlands) It is unfortunate that the miscellaneous holes, pits and depressions produced in wood, rocks and skeletons (bones, shells and tests), both pre- and post-mortem, by a wide range of invertebrates, plants and fungi, are called borings. A less inspiring name for a fascinating suite of structures is hard to imagine. Borings represent a range of activities, although most can be interpreted as feeding – predation or parasitism – or construction of a domicile (=home). Borings may or may not be assignable to a particular species, although shelly borers, such as gastropods, may rarely be preserved in situ (see, for example, Baumiller, 1990, text-fig. 1). And borings are real evidence of ancient organism-organism or organism-substrate interactions that would be impossible to determine based on the evidence of skeletal remains alone. Therefore, borings breathe life into a dead fossil record and, in truth, are exciting. Small round holes in shells Borings vary in complexity from the complicated interconnected chambers of clionoid sponges and the trace fossil (ichnogenus) Entobia Bronn (Fig. 1), to the simplicity of small round holes, formerly included in the ichnogenus Oichnus Bromley, although this is now considered a junior synonym of Sedilichnus Müller (Zonneveld and Gingras, 2014). Fig. 1. Entobia cretacea (Portlock, 1843), the Natural History Museum, London (BMNH) S.9015, clionoid sponge boring preserved in flint, chalk drift (=clay-with-flints?), Croydon, Surrey (after Donovan and Fearnhead, 2015, fig. 2). Note the cushion-shaped chambers connected by fine canals; the small tubercle-like structures in the centre of … Read More

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