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Evolution and extinction in the marine realm: some constraints imposed by phytoplanktonThe organic and mineralized remains of planktonic algae provide a rich record of microplankton evolution extending over nearly half of the preserved geological record. In general, Phanerozoic patterns of phytoplankton radiation and extinction parallel those documented for skeletonized marine invertebrates, both augmenting and constraining thought about evolution in the oceans. Rapidly increasing knowledge of Proterozoic plankton is making possible the recognition of additional episodes of diversification and extinction that antedate the Ediacaran radiation of macroscopic animals. In contrast to earlier phytoplankton history, the late Mesozoic and Cainozoic record is documented in sufficient detail to constrain theories of mass extinction in more than a general way. Broad patterns of diversity change in planktonic algae show similarities across the Cretaceous-Tertiary and Eocene-Oligocene boundaries, but detailed comparisons of origination and extinction rates in calcareous nannoplankton, as well as other algae and skeletonized protozoans, suggest that the two episodes were quite distinct. Common causation appears unlikely, casting doubt on monolithic theories of mass extinction, whether periodic or not. Studies of mass extinction highlight a broader class of insights that paleontologists can contribute to evolutionary biology: the evaluation of evolutionary change in the context of evolving Earth-surface environments.
Document ID
20040089986
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Knoll, A. H.
(Botanical Museum, Harvard University Cambridge, Massachusetts 02138, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 1989
Publication Information
Publication: Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Volume: 325
ISSN: 0962-8436
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 52-30
NASA Discipline Exobiology
Non-NASA Center
NASA Program Exobiology

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