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Nannotax3 - ntax_mesozoic - Placozygus Nannotax3 - ntax_mesozoic - Placozygus

Placozygus


Classification: ntax_mesozoic -> Eiffellithales -> Chiastozygaceae -> Placozygus
Sister taxa: Amphizygus, Archaeozygodiscus, Gorkaea, Placozygus, Reinhardtites, Tranolithus, Zeugrhabdotus ⟩⟨ Chiastozygus ⟩⟨ Staurolithites, Diadorhombus, Rhabdophidites ⟩⟨ Ahmuellerella, Bukrylithus, Diloma, Heteromarginatus, Misceomarginatus, Monomarginatus, Vacherauvillius ⟩⟨ Braloweria, Clepsilithus, Crepidolithus, Loxolithus, Neocrepidolithus, Tubirhabdus, C. - unidentified

Distinguishing features:
Parent taxon (Chiastozygaceae): Typical Eiffelithales - rim with well outer/upper clockwise-imbricate V-units and lower/inner R-units. Central area open or spanned by disjunct cross or bar supporting a spine.
This taxon: Murolith with distal/outer-cycle that shows little or no imbrication and central area spanned by transverse bars; rim exhibits spiral interference pattern.


Daughter taxa (time control age-window is: 0-800Ma)
Placozygus banneri
Small Placozygus (holotype 4.4 µm) with crossbar dark in xpl and almost filling the central area
Placozygus fibuliformis
Like P. spiralis but bar fills less of central area and formed of multiple elements
Placozygus spiralis

Placozygus sp.
Specimens not identified to species level

Taxonomy:

Citation: Placozygus Hoffman, 1970
Taxonomic rank: genus
Type species: Placozygus fibuliformis (Reinhardt, 1964) Hoffmann, 1970

Farinacci & Howe catalog pages: Placozygus *

Distinguishing features:
Parent taxon (Chiastozygaceae): Typical Eiffelithales - rim with well outer/upper clockwise-imbricate V-units and lower/inner R-units. Central area open or spanned by disjunct cross or bar supporting a spine.
This taxon: Murolith with distal/outer-cycle that shows little or no imbrication and central area spanned by transverse bars; rim exhibits spiral interference pattern.

Search data:
LITHS: murolith, elliptical, CA: bar, process, ca_disjunct, CROSS-POLARS: R-prominent, V-prominent, rim-bicyclic,
Lith size: 3.5->8µm;
Data source notes: size range of included species
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within UC9b subzone (89.49-89.95Ma, base in Turonian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

References:

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

Hoffmann, N. (1970a). Placozygus n. gen. (Coccolithineen) aus der Oberkreide des nordlichen Mitteleuropas. Geologie, Berlin. 19: 1004-1009. gs


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Placozygus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 23-3-2025

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10908 Go to Archive.is to create a permanent copy of this page - citation notes
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