Fossil folklore: Molluscs

Paul D Taylor (UK) The final article of this series on fossil folklore focuses on molluscs, excluding the ammonites, which were covered earlier (see Fossil folklore: ammonites in Deposits, Issue 46, pp. 20–23). Molluscs are second only to arthropods in the number of species living today and the resistant calcareous skeletons possessed by the majority of species accounts for their extremely rich fossil record. Most fossil molluscs belong to one of three major groups – bivalves (oysters, clams and so on), gastropods (snails and slugs) and cephalopods (ammonites, belemnites and so on). Added to these are a few minor groups, such as the monoplacophorans and scaphopods (tusk shells). Fossil molluscs are usually recognisable instantly as belonging to this phylum because of their close similarities with the shells of familiar species of modern molluscs. Some, however, are not quite so straightforward. These are more likely to have been the sources of fanciful stories about their origins and significance. Among the more obscure ancient molluscs are those dubbed ‘difficult fossils’ by Martin Rudwick in the context of the early history of palaeontology and doubts over the origin of fossils. They include the solid internal casts (steinkerns) formed by lithification of sediment enclosed by the shell and subsequent loss of the defining shell itself. In addition, there are some mollusc fossils – notably belemnite guards – that bear little resemblance to any living species, adding to their enigmatic nature. Belemnites: thunderbolts and Devil’s Fingers The first fossils I ever came across were belemnites … Read More

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Geology and fossil fauna of the South Ferriby foreshore

John P Green (UK) The large working quarry at South Ferriby, North Lincolnshire (SE991204) is a well known and productive source of Late Jurassic and Cretaceous fossils, exposing beds from the Upper Oxfordian stage, Upper Jurassic (Ampthill clay, Ringsteadia psuedocordata zone) to the Terebratulina lata zone of the Turonian stage (Welton Chalk Formation, Upper Cretaceous). Research on the stratigraphy and palaeontology of the site has been carried out by many authors, and a generalised section detailing the overall stratigraphy and macrofossil occurrences was published by the local amateur geologist, Dr Felix Whitham (1992). However, in recent years, access to the quarry for geologists has been relatively curtailed due to health and safety concerns. In light of this, my research at South Ferriby has shifted to the nearby geological exposures on the easily accessible foreshore, on the southern banks of the Humber Estuary. Fig. 1. South Ferriby foreshore, looking east. In general terms, the beds exposed on the South Ferriby foreshore tilt eastward, exposing the older (Jurassic) rocks to the west and the younger (Cretaceous) rocks to the east. The exposures are largely wave-cut platforms, accessible only at low tide, and are often covered with sand and estuarine sediments, as well as a large variety of erratic rocks and fossils. Especially prominent among the latter are carboniferous corals and limestones, Cretaceous flints, the Jurassic oyster, Gryphaea, and specimens of the Cretaceous (Late Campanian) belemnite, Belemnitella mucronata, most likely derived from chalk of this age that floors the North Sea. The low … Read More

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Essential collectibles #3: Gryphaea oysters

Dr Neale Monks (UK) One of the most interesting aspects of fossil collecting is learning about the folklore attached to them, and few fossils rival Gryphaea when it comes to this sort of thing! Known as ‘devil’s toenails’ because of their curves and gnarly shape, during medieval times they were used in magical treatments for arthritis and other types of painful joints. This is a classic example of what folklorists call sympathetic magic, where something that looks like another thing is used to influence or banish that thing. Other examples included the use of ammonites (as ‘snake stones’) to combat snakebites, and loaf-shaped Cretaceous-era sea urchins (as ‘fairy loaves’) as charms in bakeries to ensure the quality of the bread produced there. Whatever their magical value, Gryphaea are in fact a genus of oyster that were inhabitants of warm, shallow seas for an unusually long period of time. First appearing in the late Triassic about 230 millions years ago, Gryphaea-type oysters were hugely diverse during the Jurassic and Cretaceous, but unlike a lot of the organisms we associate with Mesozoic faunas they persisted into the Tertiary, the last ones into dying out in the Eocene. Actually, it’s a bit more complicated than a single lineage of oysters persisting for hundreds of millions of years, and some geologists prefer to limit the use of Gryphaea to only one particular, strictly Jurassic branch of the oyster family Gryphaeidae. Later species belong to allied, but distinct, genera such as Exogyra and Pycnodonte. One … Read More

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