Sphenolithus obtusus


Classification: Coccolithophores -> Discoasterales -> Sphenolithaceae -> Sphenolithus -> S. predistentus group -> Sphenolithus obtusus
Sister taxa: S. ciperoensis, S. distentus, S. predistentus, S. patifunditus, S. bulbulus, S. tawfikii, S. celsus, S. peartiae, S. akropodus, S. tribulosus, S. directus, S. avis, S. umbrellus, S. triangularis, S. intercalaris, S. obtusus,

Taxonomy:

Citation: Sphenolithus obtusus Bukry, 1971
Rank: Species
Synonyms: Sphenolithus pseudodistentus Gheta (1982) - decribed as differing from S. obtusus in "aspect under cross nicols" but the images show it having the typical behaviour of S. predistentus group sphenoliths. [my opinion - JRY 2016]

Distinguishing features: Medium to large (height 5-12 µm) with tall spine and low base comprising a single cycle of triangular quadrants. Spine is dark at 0° and brightest at 45°. Most spines appear monocrystalline, but some are duocrystalline; this may be orientation related.

Farinacci & Howe catalog pages: Sphenolithus obtusus * , Sphenolithus pseudodistentus *

Search data:
TagsLITHS: nannolith-radiate, N: 3D-radiate, conical, circular, RIM: tiered, PROCESS: bifurcate, duocrystalline, length-fast, spine,
CSPH: not known, V-UNITS: spine, R-UNITS: lower-tier, DETAILS: isogyres radial,
MetricsLith size: 5->12µm;
Sources: lith height from Bown (2005)
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within NP17 zone (37.32-40.40Ma, top in Priabonian stage). Data source: Bown & Dunkley Jones, 2012
First occurrence (base): within NP17 zone (37.32-40.40Ma, base in Bartonian stage). Data source: Bown & Dunkley Jones, 2012

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: Sphenolithus obtusus, synonyms included - Sphenolithus obtusus; Sphenolithus pseudodistentus; space-time plot :: Samples map :: Parent: S. predistentus group

    References:

    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. & Newsam, C. (2017). Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411). Journal of Nannoplankton Research. 37(1): 25-60. 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

    Bukry, D. (1971b). Cenozoic calcareous nannofossils from the Pacific Ocean. San Diego Society of Natural History Transactions. 16: 303-327. 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

    Shamrock, J. L. & Watkins, D. K. (2012). Eocene calcareous nannofossil biostratigraphy and community structure from Exmouth Plateau, Eastern Indian Ocean (ODP Site 762). Stratigraphy. 9(1): 1-11. gs

    Varol, O. (1998). Palaeogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 200-224. gs


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    Sphenolithus obtusus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-9-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1307 Go to Archive.is to create a permanent copy of this page - citation notes



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