Distinguishing features:
Parent taxon (Tubodiscus): Tubodiscids with high and birefringent proximal collar cycle and wide central-area. Rim image is clearly bicyclic in XPL.
This taxon: Medium sized (5-7 µm) with relatively broad shields/relatively narrow central area; in xpl inner rim cycle significantly narrower than the outer rim cycle.
Taxonomy:
Farinacci & Howe catalog pages: T. frankiae *
Distinguishing features:
Parent taxon (Tubodiscus): Tubodiscids with high and birefringent proximal collar cycle and wide central-area. Rim image is clearly bicyclic in XPL.
This taxon: Medium sized (5-7 µm) with relatively broad shields/relatively narrow central area; in xpl inner rim cycle significantly narrower than the outer rim cycle.
Morphology:
The width contrast between the two rim cycles is greater than that seen in other tubodiscids. The shield morphology and LM appearance are similar to Sollasites coccoliths, but no central area structures have been observed.
Size:
LITHS: placolith, elliptical, CA: vacant, CROSS-POLARS: R-prominent, V-prominent, rim-bicyclic, |
Lith size: 5->7µm; Data source notes: original description +/-0.5 µm |
Geological Range:
Last occurrence (top): within NC4 zone (128.82-133.09Ma, top in Hauterivian stage). Data source: Bown 2005
First occurrence (base): within NC2 zone (137.41-141.12Ma, base in Berriasian stage). Data source: Bown 2005
Plot of occurrence data:
Tubodiscus frankiae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-12-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=11275 Go to Archive.is to create a permanent copy of this page - citation notes |
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