Nannotax3 - ntax_cenozoic - Biscutaceae Nannotax3 - ntax_cenozoic - Biscutaceae


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

Circular placoliths with moderately birefringent shields, bright inner tube cycle and narrow or closed central areas.
Markalius apertus
Markalius inversus
Markalius latus
Markalius neuquenensis
Markalius walvisensis
Markalius 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: 20-4-2024

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

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