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.

Taxonomy:

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:

References:

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

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

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Comments (1)

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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?

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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.

Jeremy

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