It has been repeatedly suggested that reversals of Earth's magnetic field play a controlling role in evolution. Empirical evidence put forward to support this hypothesis has come from comparisons of the stratigraphic positions of microfossil extinctions with individual reversals and from comparisons of various estimates of changes in Phanerozoic diversity or turnover rates to some measurement of polarity change. Published associations between microfossil extinctions and magnetic reversals are reanalyzed using probabilistic techniques. The interrelationships of Phanerozoic diversity and turnover rates to measurements of the magnetic field are examined through correlation analysis. Results indicate that no currently demonstrable relationship exists between faunal extinctions and geomagnetic reversals.