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Vegetation pattern across the Cretaceous–Paleogene mass extinction (free pdf)

Ben Creisler

A new paper that may be of interest (in open access):

Vivi Vajda & Antoine Bercovici (2014)
The global vegetation pattern across the Cretaceous–Paleogene mass
extinction interval: A template for other extinction events.
Global and Planetary Change (advance online publication) Open Access
DOI: 10.1016/j.gloplacha.2014.07.014

We summarized the paleontological signal across the K-Pg boundary
The palynological signal across the K-Pg was used as template for other events
The end-Permian and end-Triassic events have similar vegetation signals as K-Pg
By comparing the palynological signals of different events, causes can
be deduced
Relative abundance data should be used to define mass-extinction events

Changes in pollen and spore assemblages across the
Cretaceous–Paleogene (K–Pg) boundary elucidate the vegetation response
to a global environmental crisis triggered by an asteroid impact in
Mexico 66 Ma. The Cretaceous–Paleogene boundary clay, associated with
the Chicxulub asteroid impact event, constitutes a unique, global
marker bed enabling comparison of the world-wide palynological signal
spanning the mass extinction event. The data from both hemispheres are
consistent, revealing diverse latest Cretaceous assemblages of pollen
and spores that were affected by a major diversity loss as a
consequence of the K–Pg event. Here we combine new results with past
studies to provide an integrated global perspective of the terrestrial
vegetation record across the K–Pg boundary. We further apply the K–Pg
event as a template to asses the causal mechanism behind other major
events in Earths history. The end-Permian, end-Triassic, and the K–Pg
mass-extinctions were responses to different causal processes that
resulted in essentially similar succession of decline and recovery
phases, although expressed at different temporal scales. The events
share a characteristic pattern of a bloom of opportunistic "crisis"
tax followed by a pulse in pioneer communities, and finally a recovery
in diversity including evolution of new taxa.

Based on their similar extinction and recovery patterns and the fact
that Last and First Appearance Datums associated with the extinctions
are separated in time, we recommend using the K–Pg event as a model
and to use relative abundance data for the stratigraphic definition of
mass-extinction events and the placement of associated
chronostratigraphic boundaries.