Discoaster mediosus


Classification: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. nodifer group -> Discoaster mediosus
Sister taxa: D. cruciformis, D. colletii, D. gemmifer, D. mediosus, D. binodosus, D. nodifer, D. distinctus, D. septemradiatus, D. tanii, D. tani ornatus, D. istanbulensis, D. martinii, D. williamsii, D. backmanii, D. okadai,

Taxonomy:

Citation: Discoaster mediosus Bramlette & Sullivan, 1961
Rank: Species
Variants: Discoaster minimus Sullivan 1964 - smaller and with fewer rays (Aubry 1984)
Notes & discussion: Discoaster mediosus and Discoaster binodosus intergrade but can be distinguished as follows: D. mediosus usually has ten rays or more, with free rays less than half the length of the central area; D. binodosus usually has 8 rays with longer free length and prominent lateral nodes and pointed ray tips.

Distinguishing features: ≥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.

Farinacci & Howe catalog pages: Discoaster mediosus * , Discoaster minimus *


Morphology remarks: Typically 8-10 rays but can have more.

Search data:
TagsLITHS: nannolith-radiate, star-shaped, RIM: free-rays-long,
CSPH: not known, V-UNITS: all, R-UNITS: none, DETAILS: 1ou,
MetricsLith size: 11->21µm; Segments: 7->9;
Sources: size from OD & illustrated specs
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within NP10 zone (54.17-55.86Ma, top in Ypresian stage). Data source: PRB entry to Nannotax
First occurrence (base): within NP7 zone (58.70-58.97Ma, base in Thanetian stage). Data source: PRB entry to Nannotax

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 mediosus, synonyms included - Discoaster mediosus; space-time plot :: Samples map :: Parent: D. nodifer group

    References:

    Aubry, M. -P. (1984). Handbook of Cenozoic calcareous nannoplankton. Book 1: Ortholithae (Discoasters). Micropaleontology Press, American Museum of Natural History, New York. 266-. gs

    Bown, P. R. & Dunkley Jones, T. (2012). Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research. 32(2): 3-51. gs

    Bown, P. R. (2005d). Palaeogene calcareous nannofossils from the Kilwa and Lindi areas of coastal Tanzania (Tanzania Drilling Project 2003-4). Journal of Nannoplankton Research. 27(1): 21-95. gs

    Bown, P. R. (2010). Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14). Journal of Nannoplankton Research. 31: 11-38. gs

    Bown, P. R. (2016). Paleocene calcareous nannofossils from Tanzania (TDP sites 19, 27 and 38). Journal of Nannoplankton Research. 36(1): 1-32. gs

    Bralower, T. J. & Self-Trail, J. (2016). Nannoplankton malformation during the Paleocene-Eocene Thermal Maximum and its paleoecological and paleoceangraphic significance. Paleoceanography. 31: 1-17. gs

    Bramlette, M. N. & Sullivan, F. R. (1961). Coccolithophorids and related nannoplankton of the Early Tertiary in California. Micropaleontology. 7(129-188): -. gs

    Perch-Nielsen, K. (1977). Albian to Pleistocene calcareous nannofossils from the Western South Atlantic, DSDP Leg 39. Initial Reports of the Deep Sea Drilling Project. 39: 699-823. gs

    Self-Trail, J. (2011). Paleogene Calcareous Nannofossils of the South Dover Bridge core, Southern Maryland (USA). Journal of Nannoplankton Research. 32(1): 1-28. gs

    Shepherd, C. L. & Kulhanek, D. K. (2016). Eocene nannofossil biostratigraphy of the mid-Waipara River section, Canterbury Basin, New Zealand. Journal of Nannoplankton Research. 26(1): 33-59. gs

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

    Wise, S. W. & Wind, F. H. (1977). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 36 drilling on the Falkland Plateau, south-west Atlantic sector of the Southern Ocean. Initial Reports of the Deep Sea Drilling Project. 36(269-491): -. gs


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    Discoaster mediosus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-9-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=480 Go to Archive.is to create a permanent copy of this page - citation notes



    Comments (1)

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    Rui da Gama

    "Short diagnosis: 8-10 near-parallel-sided rays" - several images provided herein show more than 10 rays

    Gravatar
    Jeremy Young

    good point - clearly the name is applied to forms with 11 or 12 rays, I will change the short diagnosis to >8 rays.

    Thanks for pointing his out

    Jeremy

    Page 1 of 1
     

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