Nannotax3 - ntax_mesozoic - Biscutum depravatum

Nannotax3 - ntax_mesozoic - Biscutum depravatum Nannotax3 - ntax_mesozoic - Biscutum depravatum

Biscutum depravatum

Classification: ntax_mesozoic -> Podorhabdales -> Biscutaceae -> Biscutum -> Biscutum depravatum
Sister taxa: B. constans, B. ellipticum ⟩⟨ B. coronum, B. dekaenelii, B. magnum, B. melaniae ⟩⟨ B. arrogans, B. asymmetricum, B. boletum, B. dissimilis, B. zulloii ⟩⟨ B. hattneri, B. notaculum, B. virginica ⟩⟨ B. gaultensis, B. thurowii ⟩⟨ B. davyi, B. depravatum, B. dorsetensis, B. dubium, B. erismatum, B. grande, B. intermedium, B. planum, B. profundum, B. sp.

Distinguishing features:
Parent taxon (Biscutum): Elliptical 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).
This taxon: Normally elliptical Biscutum with relatively narrow shields and open central area spanned by cross bars slightly rotated from axial. Unicyclic image in XPL.

BownCooper1998 4-04-09.jpg
Bown 1987 pl06-11.JPG
Bown 1987 pl06-12.JPG
Grun & Zweili 1980 pl05-12.JPG
Grun & Zweili 1980 pl06-01.JPG
Grun & Zweili 1980 pl06-03.JPG
Grun & Zweili 1980 pl06-02.JPG
Grun & Zweili 1980 pl06-04.JPG
Bown 1987 pl14-01.JPG
BownCooper1998 4-12-06.jpg
BarnardHay74pl5-02.JPG
Grun & Zweili 1980 f22.JPG

Taxonomy:

Citation: Biscutum depravatum (Grün & Zweili, 1980) Bown, 1987

taxonomic rank: Species

Basionym: Axopodorhabdus depravatus Grün & Zweili, 1980

Taxonomic discussion: Often cited as B. depravatus but the correct form is B. depravatum, as noted by van Heck (1990)

Farinacci & Howe catalog pages: A. depravatus *

Morphology:

The longitudinal cross-bar is slightly sinuous

Search data:

LITHS: placolith, elliptical, CA: ca_disjunct, process, diagonal cross, cross-axial, CROSS-POLARS: rim-unicyclic, V-prominent,

Lith size: 5->7µm;
Data source notes: original description

The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Middle Oxfordian Substage (156.60-159.40Ma, top in Oxfordian stage). Data source: Bown & Cooper 1998
First occurrence (base): within Aalenian Stage (170.90-174.70Ma, base in Aalenian stage). Data source: Bown & Cooper 1998

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
(NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Biscutum

References:

Barnard, T. & Hay, W. W. (1974). On Jurassic coccoliths: A tentative zonation of the Jurassic of Southern England and North France. Eclogae Geologicae Helvetiae. 67(3): 563-585. gs O

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

Bown, P. R. (1987a). Taxonomy, evolution, and biostratigraphy of Late Triassic-Early Jurassic calcareous nannofossils. Special Papers in Palaeontology. 38: 1-118. gs

Grün, W. & Zweili, F. (1980). Das kalkige Nannoplankton der Dogger-Malm-Grenze im Berner Jura bei Liesberg (Schweiz). Jahrbuch der Geologischen Bundesanstalt. 123: 231-341. gs

van Heck, S. E. (1990). The ICBN: Things you need to know - 1. INA Newsletter. 12(1): 19-20. gs

Biscutum depravatum compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 16-10-2024

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