Neochiastozygus imbriei


Classification: Coccolithophores -> 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.,

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


Taxonomy:

Citation: Neochiastozygus imbriei Haq & Lohmann, 1976
Rank: Species
Notes & 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).

Farinacci & Howe catalog pages: Neochiastozygus imbriei *

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

Search data:
TagsLITHS: murolith, elliptical, RIM: outer wall acw-imbricate, rim-narrow, CA: cross, cross-diagonal-asym,
CSPH: not known, V-UNITS: c-str, outer-rim, R-UNITS: inner-rim, DETAILS: ca_disjunct, rim-bicyclic,
MetricsLith size: 3->8µm;
Sources: 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:

  • Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
  • Taxon plotted: Neochiastozygus imbriei, synonyms included - Neochiastozygus imbrei; Neochiastozygus imbriei; space-time plot :: Samples map :: Parent: Neochiastozygus

    References:

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

    Varol, O., (1989). Palaeocene calcareous nannofossil biostratigraphy. In: Crux, J.A. and van Heck, S.E. (Editors), Nannofossils and their applications. Ellis Horwood, Chichester, pp. 265-310.

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    Neochiastozygus imbriei compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-1-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=909Go to Archive.is to create a permanent copy of this page - citation notes
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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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