D. nodifer group


Classification: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. nodifer group
Sister taxa: D. brouweri group, D. pentaradiatus group, D. quinqueramus group, D. variabilis group, D. exilis group, D. musicus group, D. deflandrei group, D. nodifer group, D. lodoensis group, D. multiradiatus group, D. araneus group, D. sp.,

Daughter taxa: (blue => in age window 0-800Ma) Granddaughter taxa
4-rayed, symetric, ray tips curved downwards

5-7 almost wedge-shaped rays separated by very narrow and deep interradial incisions (Romein 1979)

A discoaster with 8 bifurcating rays without a prominent central knob. The rays form an overlapping pattern that spirals dextrally and is distinctive of this species.

≥8 near-parallel-sided rays with rounded to pointed tips that radiate with little free length from a large circular central area. May show inter-ray ridges, a low central boss, and the development of nodes towards the ray tips.

Usually 8 rays with free ray length that approaches half the diameter of the central area or greater and prominent lateral nodes and pointed ray tips.

6-9 rayed stellate discoaster with prominent lateral nodes on their rays and ray-end notches or bifurcations.

5-6 rayed stellate discoasters; ray tips with bifurcation and lateral nodes (resemble spanners).

>6 rayed stellate discoasters; ray tips with bifurcations (similar to D. deflandrei apart from number of rays)

5 rayed stellate discoaster with long free rays of uniform width terminating in a flat or slightly notched ray-end. May show poorly developed unpaired lateral nodes on some rays.

5 rayed large stellate discoaster with prominent lateral nodes on their rays, ray-end notches or bifurcations and a stellate central boss.

Ornate 5-rayed discoaster

5 rayed, usually very large, stellate discoaster, with wide bifurcate ray tips.

5-6 rayed discoaster with broad central area that is distinctly elevated on both faces. The rays are narrow and free for around half their length. Paired lateral nodes just before the ray tips are present in some specimens

5-7 (typically 6) rayed, simple, stellate discoasters with broad, tapering rays joined along 1/2 their length.

4- to 7-rayed very large (20-45µm) discoaster, with long, thin, tapering free rays (broadest at their mid-point) and small central area.

Taxonomy:

Citation: Discoaster nodifer group - informal grouping
Rank: species group

Distinguishing features: Stellate discoasters with straight rays; rays free for >1/3 of their length; rays with bifurcations or nodes; 5-10 rays

Farinacci & Howe catalog pages:

Search data:
TagsLITHS: nannolith-radiate, star-shaped,
CSPH: not known, V-UNITS: all, R-UNITS: none, DETAILS: 1ou,
MetricsLith size: 5->45µm;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): in upper part of Rupelian Stage (74% up, 29.6Ma, in Rupelian stage). Data source: Total of range of species in this database
First occurrence (base): near base of Thanetian Stage (8% up, 59Ma, in Thanetian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:


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D. nodifer group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-10-2019

Taxon Search:
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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=422 Go to Archive.is to create a permanent copy of this page - citation notes



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