Nannotax3 - ntax_mesozoic - Discorhabdus Nannotax3 - ntax_mesozoic - Discorhabdus

Discorhabdus


Classification: ntax_mesozoic -> Podorhabdales -> Biscutaceae -> Discorhabdus
Sister taxa: Biscutum, Discorhabdus, Similiscutum ⟩⟨ Boletuvelum, Chiastella, Crucibiscutum, Gaarderella, Gephyrobiscutum, Helicorhabdus, Jimenezberrocosoia, Seribiscutum, Sollasites

Distinguishing features:
Parent taxon (Biscutaceae): Regular placoliths; rim broad, central area relatively narrow, with variable central structures.
The distal shield is formed from V-units and the proximal shield and tube cycle are formed from R-units.

This taxon: Circular, shields broad, usually without a prominent inner tube cycle; central-area typically narrow, may contain a spine.


Daughter taxa (time control age-window is: 0-800Ma)
Discorhabdus biradiatus
Discorhabdus with gaps between distal shield elements
Discorhabdus corollatus
Small Discorhabdus with narrow central area from which a tall, narrow spine protrudes.
Discorhabdus criotus
Discorhabdus with a narrow, distal inner cycle, narrow/closed central area and distal shield sutures that kink near the shield's outer edge. Bicyclic rim image.
Discorhabdus hannibalis
Small (3-5 µm), with two closely appressed shields; proximal shield is wider than the distal shield, protruding beyond it and is at least twice as thick as the distal shield in side view.
Discorhabdus ignotus
Small to medium-sized Discorhabdus with closed central area that may or may not contain a spine.
Discorhabdus patulus
Placoliths with a tall flaring spine.
Discorhabdus striatus
Medium to large Discorhabdus with closed central area.
Discorhabdus watkinsii
Species with low broad open protrusion and reduced proximal shield,
Discorhabdus sp.
Specimens not identified to species level

Taxonomy:

Citation: Discorhabdus Noël, 1965
Rank: Genus
Type species: Rhabdolithus patulus Deflandre, 1954.
Synonyms: Bidiscus Bukry 1969 - widely used in the literature
Cenorbiculus Burns 1976

Farinacci & Howe catalog pages: Discorhabdus + * , Cenorbiculus * , Bidiscus *

Distinguishing features:
Parent taxon (Biscutaceae): Regular placoliths; rim broad, central area relatively narrow, with variable central structures.
The distal shield is formed from V-units and the proximal shield and tube cycle are formed from R-units.

This taxon: Circular, shields broad, usually without a prominent inner tube cycle; central-area typically narrow, may contain a spine.

Search data:
LITHS: placolith, circular, CA: process, closed, CROSS-POLARS: rim-bicyclic, V-prominent,
Lith size: 3->8µm;
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 Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of range of species in this database
First occurrence (base): in lower part of Toarcian Stage (27% up, 180.4Ma, in Toarcian 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 O

Bown, P. R. & Young, J. R. (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 21-36. gs V O

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs O

Noël, D. (1965). Sur les Coccolithes du Jurassique Européen et d'Afrique du Nord. Essai de classification des coccolithes fossiles. Éditions du Centre National de la Recherche Scientifique, Paris. 1-209. gs


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Discorhabdus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 31-3-2023

Taxon Search:
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Short stables page link: https://mikrotax.org/Nannotax3/index.php?id=10387 Go to Archive.is to create a permanent copy of this page - citation notes



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