SPECIES ABUNDANCE CHANGES DURING MASS EXTINCTION AND THE INVERSE SIGNOR-LIPPS EFFECT: APPARENTLY ABRUPT GRAPTOLITE MASS EXTINCTION AS AN ARTIFACT OF SAMPLING

摘要

1 INTRODUCTIONGraptolites,like most marine invertebrate groups,experienced profound mass extinction during the Himantian Age at the end of the Ordovician(Chela et al.,2005；Koren,1990；Koren,1991；Melchin and Mitchell,1991；Sheehan,2001).Both genetic turnover patterns (Bambach et al.,2004)and taxon-specific,species-level data(Chen et al.,2005)reveal that the Hirnantian crash in taxonomic diversity was a consequence of accelerated extinction.