Mass Extinctions and Changing Taphonomic Processes

Abstract

The biotic crisis of the Middle Permian through Early Triassic is unmatched in the Phanerozoic in terms of taxonomic diversity losses and paleoecological reor- ganization. However, the potential taphonomic bias from post mortem diagenesis for this crucial time has not been evaluated. We assessed the quality of the fossil record during this interval by quantifying the number of Lazarus taxa using our own database, data available in the Paleobiology Database and previous compilations. We also quantitatively tested for paleoecological differences between silicified versus non-silicified faunas. Herein we report that there is no major taphonomic bias due to skeletal mineralogy or fossil preservation affecting the Middle and Late Permian fos- sil record, but that aragonite-shelled molluscs may exhibit a significant Lazarus effect during the Induan. We propose that a variety of mechanisms affected the fossil record of the Paleozoic/Mesozoic transition, including ocean chemistry, paleobiology of the examined groups, and human influences on taxonomic and sampling practices.