Paleoecological Implications of the Mineralogy, Structure, and Strontium and Magnesium Contents of Shells of the West Coast of the Genus Mytilus

Citation

Dodd, James Robert (1961) Paleoecological Implications of the Mineralogy, Structure, and Strontium and Magnesium Contents of Shells of the West Coast of the Genus Mytilus. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/9MMH-RM22. https://resolver.caltech.edu/CaltechETD:etd-04212006-171409

Abstract

Large specimens of M. californianus, M. edulis edulis, and M. edulis diegensis show a positive correlation with temperature in the percent aragonite in their shells. Shell thickness and probably other unknown factors also affect the shell mineralogy of M. californianus. Shell size and salinity are the most important factors affecting the mineralogy of M. edulis edulis and M. edulis diegensis. The shell structure of M. californianus is temperature dependent. A method making possible the quantitative determination of paleotemperatures from shell structure is devised. The age of specimens of M. californianus can be determined from shell structure making possible the estimation of growth rates, which are in part a function of temperature. The magnesium and strontium contents of the outer prismatic layer of the west coast species of Mytiles are positively correlated with temperature. The strontium content is affected by the size of the specimen but is independent of salinity in the samples in this study. The strontium content of the nacreous layer shows a negative correlation with temperature. Shell structure, strontium content, shell mineralogy, and growth rates are used to determine paleotemperatures for fossils from four localities in the upper Pleistocene of California and Baja California and one locality in the lower Pleistocene of California. These methods indicate that the temperatures were much like the present temperatures at these localities.

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