Signature of the End-Cretaceous Mass Extinction in the Modern Biota
Andrew Z. Krug,1
David Jablonski,1
James W. Valentine2
The long-term effects of mass extinctions on spatial and evolutionary
dynamics have been poorly studied. Here we show that the evolutionary
consequences of the end-Cretaceous [Cretaceous/Paleogene (K/Pg)]
mass extinction persist in present-day biogeography. The geologic
ages of genera of living marine bivalves show a significant
break from a smooth exponential distribution, corresponding
to the K/Pg boundary. The break reflects a permanent increase
in origination rates, intermediate between the Mesozoic rate
and the post-extinction recovery pulse. This global rate shift
is most clearly seen today in tropical bioprovinces and weakens
toward the poles. Coupled with the modern geographic distributions
of taxa originating before and after the K/Pg boundary, this
spatial pattern indicates that tropical origination rates after
the K/Pg event have left a permanent mark on the taxonomic and
biogeographic structure of the modern biota, despite the complex
Cenozoic history of marine environments.
2 Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, Berkeley, CA 94720, USA.
