Bown, PR; Kim, H; Gibbs, SJ; (2023) Danian calcareous nannofossil evolution and taxonomy with focus on sites from the North Atlantic Ocean (IODP Expedition 342, Sites U1403 and U1407). Journal of Nannoplankton Research , 41 (2) pp. 110-157. 10.58998/jnr3943.

Text Bown et al JNR Sept 2023 accepted with figs.pdf - Accepted Version Access restricted to UCL open access staff until 2 November 2025. Download (8MB)

Abstract

Danian nannofossil taxonomy is problematic because many of the new taxa that appeared in the aftermath of the Cretaceous/Paleogene (K/Pg) mass extinction were exceptionally small (less than 3 μm), simply constructed, morphologically similar, and inconspicuous when observed using cross-polarised light microscopy. As both identification and classification are challenging, this makes comparison of data from different workers difficult, and significantly hinders the analysis of broader questions regarding post-extinction evolutionary rates and the timing of ocean recolonisation and ecosystem recovery. Here we provide an illustrated account of Danian nannofossil taxonomy using two Integrated Ocean Drilling Program Expedition 342 sites, U1403 and U1407, that together provide a complete Paleocene composite section with good calcareous nannofossil preservation. Site U1403 includes a K/Pg boundary section that has an intact spherule layer and appears to be stratigraphically complete. The Site U1407 section is incomplete across the boundary interval due to a stratigraphic gap, but above this there is an almost complete Paleocene section with good nannofossil preservation. We describe the Danian nannofossil recovery succession recorded at both sites, focusing particularly on the survivorship record and emergence of new Cenozoic lineages. The sites reveal a succession of acme intervals, recording the incoming of new taxa and lineages, with Neobiscutum, Cruciplacolithus, Praeprinsius, Coccolithus, and Toweius being especially notable. We attempt to bring consistency to the taxonomy of these groups and address the practicality and logic of the higher taxonomy, especially the use of the genera Prinsius, Praeprinsius, Futyania, and Toweius.

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