Discoaster prepentaradiatus


Classification: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. pentaradiatus group -> Discoaster prepentaradiatus
Sister taxa: D. pentaradiatus, D. prepentaradiatus, D. hamatus, D. bellus,

Daughter taxa: Variants (could also be distinguished informally) (blue => in age window 0-800Ma)
Form with slender bifurcations
Form with broad bifurcations
4-rayed D. prepentaradiatus, often asymmetric
3-rayed D. prepentaradiatus

Taxonomy:

Citation: Discoaster prepentaradiatus Bukry and Percival, 1971
Rank: Species
Variants: As shown in the table above three and four-rayed forms of D. prepentaradiatus occur and species names have ben propsed for them. Likewise forms with robust or delicate biforcations can be spearated. We prefer to regard these as intra-specific varaints of D. prepentaradiatus.
Notes & discussion: This species is only superficially similar to D. pentaradiatus. It is complanate, and does not show any birefringence.
Browning et al. (2017) propose subdivision of the species into two sub-species based on bifurcation thickness and two new species based on ray-number. This is probably not biologically justifiable, but may be biostratigraphically useful. They explain that in the Gulf of Mexico a series of events based on these morphotypes can be consistently recognised, and have long been used. However, they also document significant range differences in the Ceara Rise Leg 154 material, so these events may be more useful for regional correlation than long-range biostratigraphy.

Distinguishing features: Symmetric with bifurcations; rays planar and all show similar birefringence.

Farinacci & Howe catalog pages: Discoaster prepentaradiatus + *


Morphology remarks: 5-rayed symmetric discoaster with broad bifurcations; rays planar and all show similar birefringence. The central area is not large but is distinct, there are usually low knobs on both the distal and proximal side.

Evolution & Phylogeny: The last occurrence of D. prepentaradiatus is close to the first occurrence of D. pentaradiatus but there is no evidence that they are directly related. It is quite possible that D. prepentaradiatus evolved from D. bollii, whilst D. pentaradiatus was independently derived from D. exilis.

Search data:
TagsLITHS: nannolith-radiate, star-shaped, RIM: tips-bifurcate, free-rays-long, PROCESS: boss, boss-proximal,
CSPH: not known, V-UNITS: all, R-UNITS: none, DETAILS: 1ou,
MetricsLith size: 8->20µm; Segments: 5->5;
Sources: size from illustrated specs
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Occurance ends in Zone NN10A
Last occurrence (top): within NN10 zone (8.29-9.53Ma, top in Tortonian stage). Data source: Young 1998
First occurrence (base): within NN9 zone (9.53-10.55Ma, base in Tortonian 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 prepentaradiatus, synonyms included - Discoaster prepentaradiatus;
  • space-time plot :: Samples map :: Parent: D. pentaradiatus group

    References:

    Bukry, D. & Percival, S. F. (1971). New Tertiary calcareous nannofossils. Tulane Studies in Geology and Paleontology. 8: 123-146. gs

    de Kaenel, E. & Villa, G. (1996). Oligocene-Miocene calcareous nannofossil biostratigraphy and paleoeecology from the Iberian Abyssal Plain. Proceedings of the Ocean Drilling Program. Scientific Results. 149: 79-145. gs

    Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gs

    Wei, W. (2003). Upper Miocene nannofossil bistratigraphy and taxonomy of Exxon core CH30-43-2 from the Gulf of Mexico. Journal of Nannoplankton Research. 25(1): 17-23. 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 prepentaradiatus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-10-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=495 Go to Archive.is to create a permanent copy of this page - citation notes



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