Geological Range: Last occurrence (top): in lower part of NN4 zone (30% up, 17Ma, in Langhian stage). Data source: Boesiger et al 2017 First occurrence (base): in upper part of NN2 zone (70% up, 20.1Ma, in Aquitanian stage). Data source: Boesiger et al 2017
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
(NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: H. ampliaperta group
Boesiger, T. M., de Kaenel, E., Bergen, J. A., Browning, E. & Blair, S. A. , . (2017). Oligocene to Pleistocene taxonomy and stratigraphy of the genus Helicosphaera and other placolith taxa in the circum North Atlantic Basin. Journal of Nannoplankton Research. 37(2-3): 145-175. gsVO
Helicosphaera alata compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 13-6-2021