Good Genes and Good Luck: Ammonoid Diversity and the End-Permian Mass Extinction

Abstract

“Rapid” Recovery The Permian-Triassic extinction 252 million years ago was Earth's most severe biotic crisis since the Precambrian and is thought to have depressed diversity in its wake for millions of years. Brayard et al. (p. 1118 ; see the Perspective by Marshall and Jacobs ) show, however, that ammonoids, a large group of marine organisms that were severely affected, recovered remarkably quickly. Only 1 million years after the extinction, ammonoids had recovered to levels higher than in the Permian, compared with the 10-million-year biotic recovery period for other benthic organisms. The Triassic recovery seems to include several cycles, but the immediate recovery of ammonoids may have left them as one of the most diverse groups in the earliest Triassic.