Daughter taxa (time control age-window is: 0-800Ma) | Granddaughter taxa | ||||
Biscutum Elliptical placoliths with broad shields with or without a prominent inner tube cycle; the central-area may be imperforate or narrow and vacant or spanned by a simple structure (plate, cross or bar). | |||||
Discorhabdus |
Taxonomy:
Distinguishing features:
Parent taxon (Mesozoic Survivors): Mesozoic taxa which occur in low abundances in the early Palaeogene.
This taxon: Placoliths with two broad shields; central area narrow; distal shield formed from V-units; proximal shield and tube formed from R-units.
Original description: Diagnosis.—Imperforate coccoliths consisting of two shields closely moulded against each other, the rays being without imbrication in either shield.
Farinacci & Howe catalog pages: Biscutaceae
Morphology:
Lith size: 3->10µm; |
Geological Range:
Last occurrence (top): at top of CP12 zone (100% up, 46.3Ma, in Lutetian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Jurassic Period (143.10-201.36Ma, base in Hettangian stage). Data source: Total of ranges 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. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 34-85. gs OReferences:
Biscutaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 12-9-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=79 Go to Archive.is to create a permanent copy of this page - citation notes |
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