Crucibiscutum


Classification: Mesozoic -> Podorhabdales -> Biscutaceae -> Crucibiscutum
Sister taxa: Biscutum, Discorhabdus, Similiscutum, Boletuvelum, Chiastella, Crucibiscutum, Gaarderella, Gephyrobiscutum, Helicorhabdus, Jimenezberrocosoia, Seribiscutum, Sollasites,

Distinguishing features: Elliptical with prominent, birefringent, axial cross.


Daughter taxa: (blue => in age window 0-800Ma)
Medium-sized (ca 5-6 µm)Crucibiscutum with relatively wide central area, relatively narrow rim and slender-armed axial cross.
Medium-sized (ca 5-7 µm), broadly elliptical Crucibiscutum; central-area relatively wide, with off-axial (slightly-rotated) cross-bars.
Small (ca 3-5 µm)Crucibiscutum with central cross that is only weakly birefringent and does not fill the central area, delineating four perforations that are clearly visible in XPL.
Crucibiscutum with an asymmetrical central cross.
Small (ca 3-5 µm) Crucibiscutum with narrow central area and birefringent cross. The central cross practically fills the narrow central area, and has the same intensity birefringence as the tube cycle (white).
Medium-sized (ca 5-6 µm), Crucibiscutum; broadly elliptical with a relatively wide central-area .

Specimens not identified to species level

Taxonomy:

Citation: Crucibiscutum Jakubowski, 1986
Rank: Genus
Type species: Cruciplacolithus salebrosus Black, 1971, designated by Jakubowski, 1986.

Farinacci & Howe catalog pages: Crucibiscutum *

Distinguishing features: Elliptical with prominent, birefringent, axial cross.

Search data:
TagsLITHS: placolith, elliptical, CA: cross-axial, ca_disjunct, process, diagonal cross, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
MetricsLith size: 3->7µm;
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 Cenomanian Stage (100% up, 93.9Ma, in Cenomanian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Berriasian Stage (0% up, 145Ma, in Berriasian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Black, M. (1971a). Coccoliths of the Speeton Clay and Sutterby Marl. Proceedings of the Yorkshire Geological Society. 38: 381-424. gs

Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Early Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 86-131. gs

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

Jakubowski, M. (1986). New calcareous nannofossil taxa from the Lower Cretaceous of the North Sea. INA Newsletter. 8: 38-42. gs V O


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Crucibiscutum compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 30-9-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10316 Go to Archive.is to create a permanent copy of this page - citation notes



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