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Nannotax3 - ntax_mesozoic - Placozygus banneri Nannotax3 - ntax_mesozoic - Placozygus banneri

Placozygus banneri


Classification: ntax_mesozoic -> Eiffellithales -> Chiastozygaceae -> Placozygus -> Placozygus banneri
Sister taxa: P. banneri, P. fibuliformis, P. spiralis, P. sp.

Distinguishing features:
Parent taxon (Placozygus): Murolith with distal/outer-cycle that shows little or no imbrication and central area spanned by transverse bars; rim exhibits spiral interference pattern.
This taxon: Small Placozygus (holotype 4.4 µm) with crossbar dark in xpl and almost filling the central area


Taxonomy:

Citation: Placozygus banneri Lees, 2007
Taxonomic rank: species

Farinacci & Howe catalog pages: P. banneri *

Distinguishing features:
Parent taxon (Placozygus): Murolith with distal/outer-cycle that shows little or no imbrication and central area spanned by transverse bars; rim exhibits spiral interference pattern.
This taxon: Small Placozygus (holotype 4.4 µm) with crossbar dark in xpl and almost filling the central area


Morphology:

"A small species of Placozygus that has the spiral-rim extinction pattern that is typical of the genus, a distinctive wide, bright inner cycle, and a dark short-axis bar, apparently composed of two blocks, that almost fills the small central area. Differentiation: This new species is distinguished from other placozygids by its wide, bright inner cycle, narrow central area and almost indistinguishable short- axis bar" [Lees 2007]

Size:
Holotype dimensions: L = 4.4μm, W = 3.08μm.

Search data:
LITHS: murolith, elliptical, CA: bar, process, ca_disjunct, CROSS-POLARS: R-prominent, V-prominent, rim-bicyclic,
Lith size: 3.5->5µm;
Data source notes: holotype and extended
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Early Maastrichtian Substage (70.10-72.17Ma, top in Maastrichtian stage). Data source: Lees 2007 (original description)
First occurrence (base): within Late Campanian Substage (72.17-76.20Ma, base in Campanian stage). Data source: Lees 2007 (original description)

Plot of occurrence data:

References:

Lees, J. A. (2007). New and rarely reported calcareous nannofossils from the Late Cretaceous of coastal Tanzania: outcrop samples and Tanzania Drilling Project Sites 5, 9 and 15. Journal of Nannoplankton Research. 29(1): 39-65. gs O


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Placozygus banneri compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 25-3-2025

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10909 Go to Archive.is to create a permanent copy of this page - citation notes
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