A computer aided palaeoecological study of selected Red Crag (Lower Pleistocene) gastropods

Harrison, Martin David (1984) A computer aided palaeoecological study of selected Red Crag (Lower Pleistocene) gastropods. Doctoral thesis, Polytechnic of North London.


The thesis sets out to study the palaeoecology and palaeoethology of the Buccinidae, Muricidae, Naticidae and Turritellidae families of gastropods from the Red Crag (Lower Pleistocene), with particular reference to interactive fauna. The Red Crag is a fully marine deposit and contains large numbers of molluscan fossils. The methods of study include much use of the computer as a tool to the Palaeontologist.

The shell shape of Nucella lapillus (L.) is studied and used as a palaeoenvironmental indicator showing that the rocky coasts of the Red Crag were not exposed to severe wave action. Neptunea conträria (L.) shell shape is analysed using Raupian parameters with a computer program and the variation in shape is recorded. A study of the encrusting organisms on the gastropod shells is undertaken and the strange phenomenon of uncoiling is explained by the overgrowth of soft bodied encrusting annelids.

A study of the diets of the hole boring muricid and naticid gastropods shows the muricids to have favoured the shallow burrowing and coarse sediment dwelling bivalves Astarte, Glycymeris and the gastropod Turritella. The naticids however favoured the bivalves Spisula and Macoma which inhabited finer grained sediments. Rates of predation in these prey are shown to be comparable to those of the present day. The distribution of borehole loci is studied using a new method of producing composite diagrams of bored bivalve populations and testing these distributions for randomness. This shows that the muricids drilled Astarte in random positions while Glycymeris was bored preferentially on the dorsal half of their valves. Naticids demonstrated great stereotypy in their drilling habits boring Macoma in the centre of their valves and Spisula close to their umbones.

Octopus predation is recorded on Nucella lapillus and predation on gastropods by crabs is studied with a discussion on the problems associated with the interpretation of aperture breaks in gastropods. From the information amassed on predation a primitive invertebrate food web is constructed.

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