Earth and Atmospheric Sciences, Department of


Date of this Version



Marine Micropaleontology 92–93 (2012) 61–80; doi 10.1016/j.marmicro.2012.05.003


U.S. government work.


Biotic response of calcareous nannoplankton to abrupt warming across the Paleocene/Eocene boundary reflects a primary response to climatically induced parameters including increased continental runoff of freshwater, global acidification of seawater, high sedimentation rates, and calcareous nannoplankton assemblage turnover. We identify ecophenotypic nannofossil species adapted to low pH conditions (Discoaster anartios, D. araneus, Rhomboaster spp.), excursion taxa adapted to the extremely warm climatic conditions (Bomolithus supremus and Coccolithus bownii), three species of the genus Toweius (T. serotinus, T. callosus, T. occultatus) adapted to warm, rather than cool, water conditions, opportunists adapted to high productivity conditions (Coronocyclus bramlettei, Neochiastozygus junctus), and species adapted to oligotropic and/or cool‐water conditions that went into refugium during the PETM (Zygrablithus bijugatus, Calcidiscus? parvicrucis and Chiasmolithus bidens). Discoaster anartios was adapted to meso- to eutrophic, rather than oligotrophic, conditions. Comparison of these data to previous work on sediments deposited on shelf settings suggests that local conditions such as high precipitation rates and possible increase in major storms such as hurricanes resulted in increased continental runoff and high sedimentation rates that affected assemblage response to the PETM.

Watkins MM 2012 Calcareous nannofossil assemblage--SUPPL1.xls (46 kB)
Table A1. Percent abundance of selected calcareous nannofossil species from the South Dover Bridge core, MD.

Watkins MM 2012 Calcareous nannofossil assemblage--SUPPL2.xls (140 kB)
Table A2. Counts of 400 calcareous nannofossil specimens from each sample in the South Dover Bridge core.

Watkins MM 2012 Calcareous nannofossil assemblage--SUPPL3.xls (37 kB)
Table A3. Counts of calcareous nannofossils of the Rhomboaster/Discoaster assemblage. Counts were tallied by noting the number of Discoaster araneus, D. anartios, and Rhomboaster spp. specimens per 100 discosters (sans D. araneus and D. anartios).