Nannotax3 - ntax_mesozoic - Nephrolithus frequens

Distinguishing features:
Parent taxon (Nephrolithus): Reniform; central-area net with two to numerous pores
This taxon: Central area with 2-15 perforations each surrounded by neat rings of rhombic elements

Citation: Nephrolithus frequens Górka, 1957

Synonyms: List from Pospichal & Wise (1990), same list given by Prins & Sissingh, in Sissingh (1977)

Nephrolithus barbarae Gorka, 1957, p. 264, pl. 5, fig. 9.
Nephrolithus furcatus Gorka, 1957, p. 263, pl. 5, fig. 8.
Nephrolithus trientis Gorka, 1957, p. 263, pl. 5, fig. 10.
Nephrolithus gorkae Åberg 1966

Geological Range:
Notes: FAD highly diachronous, occurring UCboreal20b in N. Europe; at base UC17 in the Tethyan Province; and in UC15e in the "extreme Tethyan province (Burnett 1998). Its regional FAD can be a valuable marker within the Maastrichtian but needs to be used with caution, Watkins et al. 1996, Pospichal & Wise 1990.
Last occurrence (top): within Late Maastrichtian Substage (66.04-70.10Ma, top in Maastrichtian stage). Data source: Burnett 1998
First occurrence (base): in mid part of UC15d subzone (50% up, 76.3Ma, in Campanian stage). Data source: Burnett 1998

References:

Åberg, M. (1966). Electron microscope studies on Nephrolithus (Coccolithophoraceae). Stockholm Contributions in Geology. 13: 63-67. gs

Bown, P. R. & Young, J. R. (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 21-36. gs

Bralower, T. J. & Siesser, W. G. (1992). Cretaceous calcareous nannofossil biostratigraphy of Sites 761, 762, and 763, Exmouth and Wombat Plateaus, northwest Australia. Proceedings of the Ocean Drilling Program, Scientific Results. 122: 529-556. gs

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs O

Górka, H. (1957). Les Coccolithophoridés du Maestrichtien supérieur de Pologne. Acta Palaeontologica Polonica. 2: 239-284. gs

Perch-Nielsen, K., Sadek, A., Barakat, M. G. & Teleb, F. (1978). Late Cretaceous and Early Tertiary Calcareous nannofossil and Planktonic foraminifera zones from Egypt. Actes du VI Colloque Africain de Micropaléontologie - Tunis 1974. Annales des Mines et de la Géologie Tunissienne. 28: 337-403. gs

Pospichal, J. J. & Wise, S. W. (1990). Maestrichtian calcareous nannofossil biostratigraphy of Maud Rise ODP leg 113 sites 689 and 690, Weddell Sea. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 465-487. gs

Sissingh, W. (1977). Biostratigraphy of Cretaceous calcareous nannoplankton. Geologie en Mijnbouw. 65(1): 37-65. gs

Watkins, D. K., Wise, S. W., Pospichal, J. J. & Crux, J. (1996). Upper Cretaceous calcareous nannofossil biostratigraphy and paleoceanography of the Southern Ocean. In, Moguilevsky, A. & Whatley, R. (eds) Microfossils and Oceanic Environments. University of Wales, Aberystwyth Press 355-381. gs

Nephrolithus frequens

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Sub-taxa & variants (time control age-window is: 0-800Ma)
				Nephrolithus frequens subsp. frequens Forms of N. frequens, with >2 holes in the central area (usually larger than N. frequens miniporus)
				Nephrolithus frequens subsp. miniporus Reniform to elliptical subspecies of N. frequens with only two holes within the central area.