Distinguishing features: Elliptical with prominent, birefringent, axial cross.
Daughter taxa: (blue => in age window 0-800Ma) | ||||
![]() | ![]() | ![]() | ![]() | Crucibiscutum with relatively wide central area, relatively narrow rim and slender-armed axial cross. |
![]() | ![]() | ![]() | ![]() | Medium-sized (ca 5.5 µm), broadly elliptical Crucibiscutum coccoliths with a relatively wide central-area spanned by off-axial (slightly-rotated) cross-bars. |
![]() | ![]() | Small 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 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). | ||
Specimens not identified to species level | ||||
![]() | ![]() | ![]() | ![]() | Medium-sized (ca 6.3 µm), broadly elliptical Crucibiscutum coccoliths with a relatively wide central-area spanned by axial cross-bars. |
Taxonomy:
Farinacci & Howe catalog pages: Crucibiscutum *
Distinguishing features: Elliptical with prominent, birefringent, axial cross.
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:
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 Jakubowski, M. (1986). New calcareous nannofossil taxa from the Lower Cretaceous of the North Sea. INA Newsletter. 8: 38-42. gsReferences:
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Crucibiscutum compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-12-2019
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