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