Nannotax3 - ntax_mesozoic - Helicorhabdus

Helicorhabdus


Classification: ntax_mesozoic -> Podorhabdales -> Biscutaceae -> Helicorhabdus
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 with proximal shield wider than distal; spine with helical structure


Daughter taxa (time control age-window is: 0-800Ma)
Helicorhabdus asymetricus
Helicorhabdus species with well-developed spine topped by an asymmetric plate-like calyx
Helicorhabdus sp.
Specimens not identified to species level

Taxonomy:

Citation: Helicorhabdus Lambert, 1987
Rank: Genus
Type species: Helicorhabdus asymetricus Lambert, 1987

Farinacci & Howe catalog pages: Helicorhabdus *

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 with proximal shield wider than distal; spine with helical structure


Morphology:


Size:


Ecology & Biogeography


Biology & life-cycles

Phylogenetic relations
Lambert included the genus in heterococcoliths incertae sedis, however, the basal structure seems similar to that of the Biscutaceae apart from the different relative sizes of the shields.

Search data:
LITHS: placolith, circular, CA: process, closed, CROSS-POLARS: rim-unicyclic, V-prominent,
Lith size: 1.5->2.5µm;
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 Albian Stage (100% up, 100.5Ma, in Albian stage). Data source: Total of range of species in this database
First occurrence (base): in lower part of Albian Stage (43% up, 107.6Ma, in Albian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Lambert, B. (1987). Nannofossiles calcaires de l'Albien supérieur et du Vraconnien du Cameroun méridional. Cahiers de Micropaléontologie. 2(2): 33-60. gs O


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Helicorhabdus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 30-11-2022

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10513 Go to Archive.is to create a permanent copy of this page - citation notes



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