Neochiastozygus imbriei

Classification: ntax_cenozoic -> Zygodiscales -> Zygodiscaceae -> Neochiastozygus -> Neochiastozygus imbriei
Sister taxa: N. concinnus, N. denticulatus, N. digitosus, N. distentus, N. eosaepes, N. imbriei, N. junctus, N. macilentus, N. modestus, N. perfectus, N. pusillus, N. rosenkrantzii, N. saepes, N. substrictus, N. tenansa, N. sp.


Citation: Neochiastozygus imbriei Haq & Lohmann, 1976
Rank: Species
Taxonomic discussion: In SEM these coccoliths show the presence of additional lateral bars and therefore resemble the smaller (~<3 µm) Danian species Chiastozygus ultimus Perch-Nielsen, 1981, Neochiastozygus denticulatus (Perch-Nielsen, 1969) and Neochiastozygus primitivus Perch-Nielsen, 1981, which were informally grouped as the Neochiastozygus ‘asymmetrical species’ by van Heck & Prins (1987).

Distinguishing features: Small Neochiastozygus with asymmetric cross bars rotated from axial by 10-20°.

Farinacci & Howe catalog pages: N. imbriei *

Search data:
TagsLITHS: murolith, elliptical, CA: ca_disjunct, diagonal cross, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
MetricsLith size: 3->8µm;
Data source notes: lith size from illustrated specimens (OD range of 6-9µm seems to high)
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within NP11 zone (53.70-54.17Ma, top in Ypresian stage). Data source: Bown 2005 (Varol 1989 records much lower top, witihn NP4)
First occurrence (base): within NP4 zone (61.51-63.25Ma, base in Danian stage). Data source: Varol, 1989, fig. 12.5

Plot of occurrence data:


Bown, P. R. (2005d). Palaeogene calcareous nannofossils from the Kilwa and Lindi areas of coastal Tanzania (Tanzania Drilling Project 2003-4). Journal of Nannoplankton Research. 27(1): 21-95. gs V O

Bown, P. R. (2010). Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14). Journal of Nannoplankton Research. 31(1): 11-38. gs V O

Bown, P. R. (2016). Paleocene calcareous nannofossils from Tanzania (TDP sites 19, 27 and 38). Journal of Nannoplankton Research. 36(1): 1-32. gs V O

Bown, P. R., Gibbs, S. J., Sheward, R., O’Dea, S. & Higgins, D. (2014). Searching for cells: the potential of fossil coccospheres in coccolithophore research. Journal of Nannoplankton Research. 34(special): 5-21. gs V O

Bybell, L. M. & Self-Trail, J. (1995). Evolutionary, biostratigraphic and taxonomic study of calcareous nanofossils from a continuous Palaeocene-Eocene boundary section in New Jersey. U.S. Geological Survey, Professional Paper. 1554: 1-36. gs V O

Haq, B. U. & Lohmann, G. P. (1976). Early Cenozoic calcareous nannoplankton biogeography of the Atlantic Ocean. Marine Micropaleontology. 1: 119-194. gs

Okada, H. & Thierstein, H. R. (1979). Calcareous nannoplankton - Leg 43, Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project. 43: 507-573. gs V O

Perch-Nielsen, K. (1977a). Albian to Pleistocene calcareous nannofossils from the Western South Atlantic, DSDP Leg 39. Initial Reports of the Deep Sea Drilling Project. 39: 699-823. gs V O

Perch-Nielsen, K. (1981b). New Maastrichtian and Paleocene calcareous nannofossils from Africa, Denmark, and USA and the Atlantic, and some Paleocene lineages. Eclogae Geologicae Helvetiae. 74(3): 831-863. gs V O

Shepherd, C. L. & Kulhanek, D. K. (2016). Eocene nannofossil biostratigraphy of the mid-Waipara River section, Canterbury Basin, New Zealand. Journal of Nannoplankton Research. 26(1): 33-59. gs V O

Steurbaut, E. & Sztrákos, K. (2008). Danian/Selandian boundary criteria and North Sea Basin–Tethys correlations based on calcareous nannofossil and foraminiferal trends in SW France. Marine Micropaleontology. 67: 1-29. gs

Varol, O. (1989c). Palaeocene calcareous nannofossil biostratigraphy. In, Crux, J. A. & van Heck, S. E. (eds) Nannofossils and their applications: Proceedings of the 2nd INA Conference, London 1987. British Micropalaeontological Society Publication Series. 265-310. gs V O


Neochiastozygus imbriei compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 21-1-2021

Taxon Search:
Advanced Search

Short stable page link: Go to to create a permanent copy of this page - citation notes

Comments (1)

Sort By
Page 1 of 1
Rui da Gama

Broad and narrow elliptical forms are herein included as N. imbriei. Also, there seems to be significant variations in size... Could we consider subdividing this group further?

Jeremy Young (Tonbridge, UK)

Hi Rui - sorry for a slow reply, that is a bit outside my expertise. Personally I have enough problems with the existing taxonomy not to want to encourage splitting further, and the coccospheres from Paul Bown show a lot of coccolith variation which again makes me cautious. Neochiastozygus is an interesting group though, and it would be nice if someone could find some good material and do a detailed study. Indeed with good material it could make a good masters project.


Page 1 of 1

Add Comment

* Required information
Captcha Image
Powered by Commentics