Distinguishing features:
Parent taxon (R. lockeri group): Elliptical reticulofenestrids with relatively open central area spanned on the proximal surface by a robust grill (clearly visible in lm as a birefringent plate with variable number of perforations).
This taxon: Large to very large (>10 µm) with wide central area, net weakly visible in LM
| LITHS: placolith, elliptical, CA: ca_conjunct, grill, closed, CSPH: equant, monomorphic, CROSS-POLARS: rim-unicyclic, R-prominent, |
| Lith size: 10->14µm; |
Geological Range:
Last occurrence (top): within NP15c subzone (42.87-44.12Ma, top in Lutetian stage). Data source: Bown & Newsam 2017
First occurrence (base): within NP15b subzone (44.12-45.49Ma, base in Lutetian stage). Data source: Bown & Newsam 2017
Plot of occurrence data:
Bown, P. R. & Newsam, C. (2017). Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411). Journal of Nannoplankton Research. 37(1): 25-60. gs O De Kaenel, E. & Mojon, P. -O. (2023). Calcareous nannofossil biostratigraphy of the Eocene/Oligocene boundary (Zones NP19–21) in the parautochthonous Subalpine UMM of the Swiss Molasse Basin (Canton Fribourg, Western Switzerland). Journal of Nannoplankton Research. 41(2): 64-96. gs O Perch-Nielsen, K. (1971c). Elektronenmikroskopische untersuchungen an Coccolithen und verwandten Formen aus dem Eozan von Danemark. Biologiske Skrifter, Kongelige Danske Videnskabernes Selskab. 18(3): 1-76. gs O Wise, S. W. (1983). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 71 in the Falkland Plateau region, Southwest Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 71: 481-550. gs OReferences:

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Reticulofenestra onusta compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-7-2026
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