Sphenolithus obtusus


Classification: ntax_cenozoic -> 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: S. obtusus * , S. pseudodistentus *

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, CA: process, CROSS-POLARS: V-prominent, R-prominent,
MetricsLith size: 5->12µm;
Data source notes: 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:

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 V O

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 V O

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 V O

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

Fioroni, C., Villa, G., Persico, D. & Jovane, L. (2015). Middle Eocene-Lower Oligocene calcareous nannofossil biostratigraphy and paleoceanographic implications from Site 711 (equatorial Indian Ocean). Marine Micropaleontology. 118: 50-62. gs

Jones, A. P. & Dunkley Jones, T. (2020). Middle Eocene to Early Oligocene calcareous nannofossils from the Nanggulan Formation, Java, Indonesia. Journal of Nannoplankton Research. 30(1): 57-79. gs V O

Perch-Nielsen, K. (1977a). 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 V O

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: 19-4-2021

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Short stable page link: https://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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