Placozygus


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

Distinguishing features: 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: (blue => in age window 0-800Ma)
Small Placozygus (holotype 4.4 µm) with crossbar dark in xpl and almost filling the central area
Like P. spiralis but bar fills less of central area and formed of multiple elements

Specimens not identified to species level

Taxonomy:

Citation: Placozygus Hoffman, 1970
Rank: Genus
Type species: Placozygus fibuliformis (Reinhardt, 1964) Hoffmann, 1970

Farinacci & Howe catalog pages: Placozygus *

Distinguishing features: Murolith with distal/outer-cycle that shows little or no imbrication and central area spanned by transverse bars; rim exhibits spiral interference pattern.

Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Turonian Stage (77% up, 90.7Ma, in Turonian stage). Data source: Total of range 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

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


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Placozygus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-9-2019

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Short stable page link: http://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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