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Ichthyosaur extinction in Cenomanian (free pdf)

Ben Creisler

A new paper with free pdf:

Valentin Fischer, Nathalie Bardet, Roger B. J. Benson, Maxim S.
Arkhangelsky & Matt Friedman (2016)
Extinction of fish-shaped marine reptiles associated with reduced
evolutionary rates and global environmental volatility.
Nature Communications 7, Article number: 10825
http: // www.nature.com/ncomms/2016/160308/ncomms10825/full/ncomms10825.html

Despite their profound adaptations to the aquatic realm and their
apparent success throughout the Triassic and the Jurassic,
ichthyosaurs became extinct roughly 30 million years before the
end-Cretaceous mass extinction. Current hypotheses for this early
demise involve relatively minor biotic events, but are at odds with
recent understanding of the ichthyosaur fossil record. Here, we show
that ichthyosaurs maintained high but diminishing richness and
disparity throughout the Early Cretaceous. The last ichthyosaurs are
characterized by reduced rates of origination and phenotypic evolution
and their elevated extinction rates correlate with increased
environmental volatility. In addition, we find that ichthyosaurs
suffered from a profound Early Cenomanian extinction that reduced
their ecological diversity, likely contributing to their final
extinction at the end of the Cenomanian. Our results support a growing
body of evidence revealing that global environmental change resulted
in a major, temporally staggered turnover event that profoundly
reorganized marine ecosystems during the Cenomanian.



http: // phys.org/news/2016-03-slower-evolution-climate-drove-ichthyosaurs.html