A compilation of worldwide taxonomic diversity data for Recent Bivalvia shows a consistent poleward decrease in numbers of species, genera, and families. Spherical harmonic surfaces fitted to the raw data of bivalve diversity accurately predict the position of the present equator and rotational poles at each of the three taxonomic levels examined. These findings suggest that diversity studies of fossils at the specific, generic, or familial levels will prove useful for determining ancient equator and pole positions. In addition, residuals from the fitted surfaces show promise of indicating local areas of anomalous geographic or climatic history.

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