Nannotax3 - ntax_mesozoic - Bibreviconus

Bibreviconus


Classification: ntax_mesozoic -> Watznaueriales -> Watznaueriaceae -> Bibreviconus
Sister taxa: Bussonius, Cyclagelosphaera, Diazomatolithus, Lotharingius, Watznaueria ⟩⟨ Ansulasphaera, Bibreviconus, Perchnielsenella

Distinguishing features:
Parent taxon (Watznaueriaceae): Placoliths or modified placoliths with R-unit well developed, forming proximal and distal shield elements with opposite senses of imbrication; the V-unit typically forms a narrow distal cycle near the inner edge of the shield. Central-area structures are typically disjunct. Birefringent LM image, in which the V-unit cycle appears only as a thin, dark line.
This taxon: High, cylindrical morphology with a peg-like distal cycle; possibly the isolated central part of Cyclagelosphaera deflandrei specimens which have lost the shields.


Daughter taxa (time control age-window is: 0-800Ma)
Bibreviconus atlanticus
High, cylindrical morphology with a peg-like distal cycle; possibly the isolated central part of Cyclagelosphaera deflandrei specimens which have lost the shields.
Bibreviconus sp.
Specimens not identified to species level

Taxonomy:

Citation: Bibreviconus Rahman & Roth, 1991
Rank: Genus
Type species: Bibreviconus atlanticus Rahman and Roth, 1991

Farinacci & Howe catalog pages: Bibreviconus *

Distinguishing features:
Parent taxon (Watznaueriaceae): Placoliths or modified placoliths with R-unit well developed, forming proximal and distal shield elements with opposite senses of imbrication; the V-unit typically forms a narrow distal cycle near the inner edge of the shield. Central-area structures are typically disjunct. Birefringent LM image, in which the V-unit cycle appears only as a thin, dark line.
This taxon: High, cylindrical morphology with a peg-like distal cycle; possibly the isolated central part of Cyclagelosphaera deflandrei specimens which have lost the shields.

Search data:
TagsLITHS: placolith, circular, elliptical, cylindrical, CA: closed, CROSS-POLARS: rim-unicyclic, R-prominent,
MetricsLith size: 3->5µm;
Data source notes: size range of included species
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 Tithonian Stage (100% up, 145Ma, in Berriasian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Tithonian Stage (0% up, 152.1Ma, in Kimmeridgian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

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

Rahman, A. & Roth, P. H. (1991). Upper Jurassic calcareous nannofossils from the DSDP Site 534 in the Blake Bahama Basin, western North Atlantic. Eclogae Geologicae Helvetiae. 84: 765-789. gs V O


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Bibreviconus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 9-12-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10055 Go to Archive.is to create a permanent copy of this page - citation notes



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