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Nannofossil evolutionary events in the mid-Pliocene: an assessment of the degree of synchrony in the extinctions of Reticulofenestra pseudoumbilicus and Sphenolithus abies

Nannofossil evolutionary events in the mid-Pliocene: an assessment of the degree of synchrony in the extinctions of Reticulofenestra pseudoumbilicus and Sphenolithus abies
Nannofossil evolutionary events in the mid-Pliocene: an assessment of the degree of synchrony in the extinctions of Reticulofenestra pseudoumbilicus and Sphenolithus abies
The mid-Pliocene was an interval of subtle reorganisation within the nannoplankton community, including the prominent and biostratigraphically important last occurrences of Sphenolithus abies and Reticulofenestra pseudoumbilicus. The transition is part of the Pliocene to Recent ‘attrition’ of nannofossil species that resulted from changes in the distribution of trophic resources, and deep-water and surface-water current systems, likely associated with the initiation of Northern Hemisphere glaciation.
The extinctions of Sphenolithus abies and Reticulofenestra pseudoumbilicus were analysed in detail at ODP Sites 659, 662, and 926 in the equatorial and subequatorial Atlantic. These taxa show significantly different patterns of duration and timing of decline based on high-resolution abundance records and calibration with oxygen isotope stratigraphy. The initiation of abundance decline between 3.71 and 3.67 Ma and the extinction of S. abies between 3.56 and 3.52 Ma are diachronous. This extinction may have been a response to the intensification of glacial intervals at this time. In contrast, the last occurrence of R. pseudoumbilicus at 3.81–3.82 Ma appears to be a valid example of biostratigraphic (although not necessarily biological) synchrony in the fossil record. Direct environmental forcing is not attributable for the extinction of R. pseudoumbilicus; however, indirect physical and/or biological environmental stress may explain the observed patterns.
pliocene, central atlantic, calcareous nannofossils, biostratigraphy, evolution, extinction
0031-0182
155-172
Gibbs, Samantha J.
82dfbcbc-3a8a-40da-8a80-fe7ad83f3110
Young, Jeremy R.
18d63549-d248-4012-91b1-64382581ef53
Bralower, Timothy J.
8d16a733-85c8-4837-aa95-f070d61494a7
Shackleton, Nicholas J.
eb79241d-5230-4332-8eee-78f57c1ca03b
Gibbs, Samantha J.
82dfbcbc-3a8a-40da-8a80-fe7ad83f3110
Young, Jeremy R.
18d63549-d248-4012-91b1-64382581ef53
Bralower, Timothy J.
8d16a733-85c8-4837-aa95-f070d61494a7
Shackleton, Nicholas J.
eb79241d-5230-4332-8eee-78f57c1ca03b

Gibbs, Samantha J., Young, Jeremy R., Bralower, Timothy J. and Shackleton, Nicholas J. (2005) Nannofossil evolutionary events in the mid-Pliocene: an assessment of the degree of synchrony in the extinctions of Reticulofenestra pseudoumbilicus and Sphenolithus abies. Palaeogeography, Palaeoclimatology, Palaeoecology, 217 (1-2), 155-172. (doi:10.1016/j.palaeo.2004.11.005).

Record type: Article

Abstract

The mid-Pliocene was an interval of subtle reorganisation within the nannoplankton community, including the prominent and biostratigraphically important last occurrences of Sphenolithus abies and Reticulofenestra pseudoumbilicus. The transition is part of the Pliocene to Recent ‘attrition’ of nannofossil species that resulted from changes in the distribution of trophic resources, and deep-water and surface-water current systems, likely associated with the initiation of Northern Hemisphere glaciation.
The extinctions of Sphenolithus abies and Reticulofenestra pseudoumbilicus were analysed in detail at ODP Sites 659, 662, and 926 in the equatorial and subequatorial Atlantic. These taxa show significantly different patterns of duration and timing of decline based on high-resolution abundance records and calibration with oxygen isotope stratigraphy. The initiation of abundance decline between 3.71 and 3.67 Ma and the extinction of S. abies between 3.56 and 3.52 Ma are diachronous. This extinction may have been a response to the intensification of glacial intervals at this time. In contrast, the last occurrence of R. pseudoumbilicus at 3.81–3.82 Ma appears to be a valid example of biostratigraphic (although not necessarily biological) synchrony in the fossil record. Direct environmental forcing is not attributable for the extinction of R. pseudoumbilicus; however, indirect physical and/or biological environmental stress may explain the observed patterns.

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More information

Published date: 11 February 2005
Keywords: pliocene, central atlantic, calcareous nannofossils, biostratigraphy, evolution, extinction

Identifiers

Local EPrints ID: 37839
URI: http://eprints.soton.ac.uk/id/eprint/37839
ISSN: 0031-0182
PURE UUID: 4faf3ffb-b9d3-4e60-ad44-1b1e6caa0155

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Date deposited: 26 May 2006
Last modified: 15 Mar 2024 08:01

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Contributors

Author: Samantha J. Gibbs
Author: Jeremy R. Young
Author: Timothy J. Bralower
Author: Nicholas J. Shackleton

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