Two equations regarding preservation probability were incorrectly given in a recent paper (Foote 2000). As presented therein, equation (24a) disregards taxa extant at the start of the time span of interest, and equation (25a) ignores taxa extant at the end of this time span. It is necessary to add a single term to each equation to yield the correct forms:
Results presented were based on the correct equations. The conclusions of the paper therfore do not need to be modified.