Zygodiscus


Classification: ntax_cenozoic -> Zygodiscales -> Zygodiscaceae -> Zygodiscus
Sister taxa: Lophodolithus, Neochiastozygus, Zygodiscus ⟩⟨ Chiphragmalithus, Isthmolithus, Neococcolithes, Nannotetrina

Daughter taxa (time control age-window is: 0-800Ma)
Zygodiscus adamas
Zygodiscus with “lozenge-shaped” bar.
Zygodiscus cearae
Large (11.0-13.5 µm) murolith coccolith with a broad central-area spanned by a transverse bar made up of crystallographically distinct units that appear as low-angle diagonal cross-bars at certain orientations in XPL.
Zygodiscus clausus
Medium sized elliptical murolith comprising an unadorned plate with a central hole spanned and filled by a disjunct bar. The precise crystallographic orientation of the bar appears to vary.
Zygodiscus herlyni

Zygodiscus multiforus
Medium- to large-sized elliptical murolith with a relatively broad, birefringent rim that has a perforate appearance on one side. The central-area is spanned by a transverse bar.
Zygodiscus plectopons
Murolith with wide central area spanned by a parallel side bar.
Zygodiscus sheldoniae
Medium to large sized murolith with a broad plate enclosing a small disjunct bar.
Zygodiscus sp.
Specimens which cannot be assigned to any established species

Taxonomy:

Citation: Zygodiscus Bramlette and Sullivan, 1961
Rank: Genus
Type species: Zygodiscus adamas Bramlette & Sullivan, 1961

Distinguishing features: Muroliths with well-developed V- and R-units and transverse bar in central-area. LM image is dominated by bright, broad R-unit inner cycle; V-unit cycle is narrow.

Farinacci & Howe catalog pages: Zygodiscus + + *


Size: Coccolith medium to large size (5-14 µm), no great size variation between species.

Search data:
TagsLITHS: murolith, elliptical, CA: ca_disjunct, bar, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
MetricsLith size: 5->14µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: The decribed species are not well-differentitated and all appear to have similar ranges, predominantly occurring in the Late Paleocene (NP6 to NP9) but extending into the Early Eocene (NP10-11).
Last occurrence (top): in lower part of Ypresian Stage (28% up, 53.7Ma, in Ypresian stage). Data source: Total of range of species in this database
First occurrence (base): near top of Selandian Stage (87% up, 59.5Ma, in Selandian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bramlette, M. N. & Sullivan, F. R. (1961). Coccolithophorids and related nannoplankton of the Early Tertiary in California. Micropaleontology. 7(2): 129-188. gs


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Zygodiscus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 16-4-2021

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1516 Go to Archive.is to create a permanent copy of this page - citation notes



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