Biscutaceae


Ancestry: Coccolithophores -> Mesozoic Survivors -> Biscutaceae
Sister taxa: Biscutaceae, Chiastozygaceae, Markalius, Watznaueriaceae,

Short diagnosis: Placoliths with two broad shields; central area narrow; distal shield formed from V-units; proximal shield and tube formed from R-units.


Daughter taxa (blue => in age window 0-300Ma) 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).

Taxonomy:

Citation: Biscutaceae Black, 1971
Rank: Family

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

Short diagnosis: Placoliths with two broad shields; central area narrow; distal shield formed from V-units; proximal shield and tube formed from R-units.


Morphology remarks: 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:
TagsLITHS: placolith, circular, elliptical,
MetricsLith size: 3->10┬Ám;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Lutetian Stage (41.15-47.84Ma, top in Lutetian stage). Data source: Total of range of species in this database
First occurrence (base): within Berriasian Stage (139.39-145.01Ma, base in Berriasian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

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

Bown, P.R. & Cooper, M.K.E., (1998). Jurassic. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 34-85.


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Biscutaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 23-10-2017

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