Morphogenetic regulation in the shells of bivalves and brachiopods: evidence from the geometry of the spiral |
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Authors: | SPAFFORD C. ACKERLY |
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Affiliation: | Department of Geology and Applied Geology, University of Glasgow, Glasgow, G12 8QQ, UK. |
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Abstract: | Ackerly. S. C. 1992 07 15: Morphogenetic regulation in the shells of bivalves and brachiopods: evidence from the geometry of the spiral. Analyses of the spiral geometry in shells of the mollusc Pecten maximus and the brachiopod Terebratulina retusa indicate a relative reduction in morphological variability within the population during growth. The spiral, as measured by a model of exponential radial expansion, tends to converge on a particular adult form, irrespective of irregularities during early growth phases. The recurrence of this pattern of variability in populations from two separate phyla (molluscs and brachiopods) suggests a common mechanism controlling shell form. Brachiopoda. Mollusca, coiling, spiral. morphogenetic regulation, growth . |
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