The end-Cretaceous mass extinction in the marine realm: year 2000 assessment

TitleThe end-Cretaceous mass extinction in the marine realm: year 2000 assessment
Publication TypeJournal Article
Year of Publication2001
AuthorsKeller, G
JournalPlanetary and Space Science
Pagination817 - 830
Date PublishedJan-07-2001

The current database indicates that the terminal decline and extinction, or near extinction, of many groups commonly attributed to an asteroid or comet impact at the Cretaceous–Tertiary (K–T) boundary (e.g., ammonites, bivalves, planktic foraminifera) began during the last 500 k:y: of the Maastrichtian. By the time of the K–T boundary, extinction-prone tropical and subtropical marine faunas and 4oras were almost gone, or had severely reduced species populations struggling to survive. The K–T boundary kill-e5ect was largely restricted to these struggling tropical and subtropical populations that accounted for 2=3 of the species among planktic foraminifera, but less than 10% of the total foraminiferal population. No signi7cant extinctions occurred among ecological generalists that dominated across latitudes. No single kill mechanism can account for this mass extinction pattern. The last 500 k:y: of the Maastrichtian were characterized by a series of rapid and extreme climate changes characterized by 3–4◦C warming between 65.4 and 65:2 Ma, major volcanic activity between 65.4 and 65:2 Ma, a spherule-producing event between 65.3 and 65:2 Ma, and an impact at the K–T boundary (65:0 Ma). All of these events caused major environmental perturbations and biotic stresses that resulted in severe reductions in species populations and extinctions that culminated at the K–T boundary. The mass extinction pattern, and the parallel environmental changes during the last 500 k:y: of the Maastrichtian, suggest that both long-term (climate, sea-level) and short-term (impact, volcanism) events contributed to the K–T boundary mass extinction.   PDF

Short TitlePlanetary and Space Science