Ammonoid diversity and disparity track episodes of chaotic carbon cycling during the early Mesozoic

Episodes of mass extinction represent the largest events of biodiversity loss known in the geologic record, and may provide tests of biodiversity-ecosystem stability hypotheses. Here we present the first correlation between ammonoid diversity and disparity and ecosystem stability as represented by s...

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Bibliographic Details
Published in:Geology (Boulder) 2011-02, Vol.39 (2), p.99-102
Main Authors: Whiteside, Jessica H, Ward, Peter D
Format: Article
Language:English
Subjects:
Ammonoidea
behavior
Biodiversity
Biogeography
Carbon
Carbon cycle
Cephalopoda
chaotic behavior
Ecosystems
Extinction
geochemical cycle
geochemistry
Invertebrata
invertebrate
Isotopes
lower Mesozoic
Lower Triassic
mass extinctions
Mesozoic
Mollusca
morphology
paleoecology
Paleontology
Paleozoic
Permian
Permian-Triassic boundary
species diversity
stratigraphic boundary
Stratigraphy
Triassic
Upper Permian
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Summary:Episodes of mass extinction represent the largest events of biodiversity loss known in the geologic record, and may provide tests of biodiversity-ecosystem stability hypotheses. Here we present the first correlation between ammonoid diversity and disparity and ecosystem stability as represented by stable carbon isotopic records spanning the end-Permian through end-Triassic mass extinctions. Ammonoid generic richness from a single biogeographic realm shows that nearly all taxa disappeared coincident with major carbon isotopic shifts to lighter values. The intervals following these two major mass extinctions were characterized by multiple positive-negative couplets of chaotic carbon cycling and were composed of low-richness ammonoid faunas characterized by higher proportions of passively floating, non-swimming morphotypes than before or after. In contrast, richness was highest during intervals of stable carbon isotope values. We propose that these "chaotic carbon episodes" reflect the breakdown of functional redundancy in the ecosystem, and that the post-extinction carbon cycle did not stabilize until redundancy was restored.
ISSN:0091-7613
1943-2682
DOI:10.1130/G31401.1