Nannotax3 - ntax_cenozoic - Biscutaceae Nannotax3 - ntax_cenozoic - Biscutaceae


Classification: ntax_cenozoic -> Mesozoic Survivors -> Biscutaceae
Sister taxa: Biscutaceae, Chiastozygaceae, Markalius, Watznaueriaceae

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
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).
Biscutum harrisonii
Biscutum braloweri
Biscutum neocoronum
Biscutum sp.


Discorhabdus ignotus
Discorhabdus sp.


Citation: Biscutaceae Black, 1971
taxonomic rank: Family

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.

Farinacci & Howe catalog pages: Biscutaceae [no catalog entry yet]


Placoliths with two broad shields that may or may not include a distal inner-cycle (tube cycle). The relatively narrow central areas are vacant, filled with granular calcite or spanned by variably oriented bars or axial cross-bars. The distal shield is formed from V-units and the proximal shield and tube cycle are formed from R-units; the distal shield elements are joined along radial or near-radial sutures (+/- 'kinks') and show little or no imbrication. The LM image is generally dark, but bright inner-cycles are common. Coccospheres are well known and usually spherical or cylindrical.

Search data:
Lith size: 3->10µm;
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 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 O


Biscutaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 25-7-2024

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Short stable page link: Go to to create a permanent copy of this page - citation notes

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