Discoaster druggii


Classification: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. deflandrei group -> Discoaster druggii
Sister taxa: D. deflandrei, D. calculosus, D. salomonii, D. emblematicus, D. durioi, D. saundersi, D. nephados, D. leroyi, D. kugleri, D. hexapleuros, D. cuspidatus, D. druggii, D. shumnykii,

Taxonomy:

Citation: Discoaster druggii Bramlette and Wilcoxon, 1967
Rank: Species
Variants: de Kaenel et al. (2017) record three size variants with significantly different ranges:
Synonyms: Discoaster extensus Bramlette and Wilcoxon, 1967 (invalid because homonym of D. extensus Hay et al. The replacement name D. druggii was proposed in the next issue of the journal).
Notes & discussion: D. druggii is essentially a variety of D. deflandrei but is more consistently developed than most others. It is characterised by its large size, and by tapering rays ending in a terminal notch and lateral nodes, but no true bifurcations. A weak distal knob may be present but otherwise both sides are featureless.

de Kaenel et al. (2017) provide by far the best documentation of this species and greatly clarify its use. In particular they show that the most age-diagnostic large forms (>15 µm) have a restrted range from NN2 to NN3 whilst smaller forms range from NP26 to NN5 

Original description:  Asterolith large and varying greatly in peripheral outline, with six rays that may be bluntly rounded, truncated, or notched at the rips. The central area is broad and nearly flat or complanate. Specimens are distinctly rugose, and commonly show indistinct sutures, extending from the center to the margin between the rays. Diameter 15-22 µm usually about 18µm·
Remarks: Despite much variation in outline illustrated by the seven specimens, all gradations occur in this character [i.e. outline] in the single sample where the species is common, making any subdivision difficult and of questionable value. [Bramlette & Wilcoxon 1967]

Distinguishing features: Like D. deflandrei but larger, >15µm, and without distinct bifurcations

Farinacci & Howe catalog pages: Discoaster druggi + * ,

Search data:
TagsLITHS: nannolith-radiate, star-shaped, RIM: tips-bifurcate, free-rays-long,
CSPH: not known, V-UNITS: all, R-UNITS: none, DETAILS: 1ou,
MetricsLith size: 15->22µm; Segments: 6->6;
Sources: size from OD
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: In the absence of more reliable markers its first occurrence is used as the base of NN2.
de Kaenel et al. (2017) record three size variants with separate ranges:


Last occurrence (top): within NN3 zone (17.95-19.00Ma, top in Burdigalian stage). Data source: Young 1998
First occurrence (base): within NN2 zone (19.00-22.82Ma, base in Aquitanian stage). Data source: Young 1998

Plot of occurrence data:

  • Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
  • Note to users in China - the diagram may not plot unless you use a VPN since I use google services on the website. If this is a problem please contact me 谢谢.
  • Taxon plotted: Discoaster druggii, synonyms included - Discoaster druggii; Discoaster druggii (< 15 microns); space-time plot :: Samples map :: Parent: D. deflandrei group

    References:

    Bramlette, M. N. & Wilcoxon, J. A. (1967b). Middle Tertiary calcareous nannoplankton of the Cipero section, Trinidad, W.I. Tulane Studies in Geology and Paleontology. 5: 93-131. gs

    Bramlette, M. N. & Wilcoxon, J. A. (1967a). Discoaster druggi nom. nov. pro Discoaster extensus Bramlette and Wilcoxon, 1967, non Hay, 1967. Tulane Studies in Geology and Paleontology. 5: 220-. gs

    Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gs


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    Discoaster druggii compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 16-7-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=467 Go to Archive.is to create a permanent copy of this page - citation notes



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