Figure 1. Heuristic diagram showing diversity patterns of significant classes of taxa during mass extinction and postextinction intervals. Many taxa will disappear from the record prior to the onset of the extinction event simply due to incomplete preservation. Other taxa (Lazarus taxa) will be absent from the fossil record for significant periods following the extinction, for both preservational and ecological reasons. Disaster and opportunistic taxa flourish during the survival interval immediately after an event, but then wane in importance as other lineages begin to recover. Disaster taxa are very rare except following significant biodiversity crises, while opportunistic taxa are present, but of less abundance except in disturbed habitats or after ecological disturbances that allow such ‘weedy’ species to become abundant. The appearance of newly diversifying lineages generally marks the end of the survival interval and the onset of the recovery interval. Each recovery is different, however, and different lineages will display different patterns during the same recovery.