Sphenolithus heteromorphus


Ancestry: Coccolithophores -> Discoasterales -> Sphenolithaceae -> Sphenolithus -> S. heteromorphus group -> Sphenolithus heteromorphus
Sister taxa: S. belemnos, S. calyculus, S. delphix, S. disbelemnos, S. milanetti, S. pospichalii, S. pseudoheteromorphus, S. heteromorphus,

Short diagnosis: Apical spine very well-developed. Lateral elements nearly as large as proximal elements.


Taxonomy:

Citation: Sphenolithus heteromorphus Deflandre 1953
Rank: Species
Notes & discussion: S. heteromorphus has a well developed quadrate base, in which the the upper part is nearly as large as the proximal part, which distinguishes it clearly from S. belemnos. Also the spine typically has a rather bulbous base in contrast to the straight-sided S. belemnos.

Farinacci & Howe catalog pages: Sphenolithus heteromorphus *

Short diagnosis: Apical spine very well-developed. Lateral elements nearly as large as proximal elements.


Size: Length 5-15 microns, varies considerably in all populations, possibly in part due to diagenetic overgrowth. Width usually c. 3-5 microns.

Geological Range:
Notes: Prone to reworking
Last occurrence (top): at top of NN5 zone (100% up, 13.5Ma, in Serravallian stage). Data source: zonal marker (see e.g. Young 1998)
First occurrence (base): at base of NN4 zone (0% up, 18Ma, in Burdigalian stage). Data source: FAD is very close to NN4 base , se e.g. Young (1998)

Plot of occurrence data:

References:

Deflandre, G., (1953). Hétérogénéité intrinsèque et pluralité des éleménts dans les coccolithes actuels et fossiles. Comptes Rendus (Hebdomadaires des Séances) de l'Académie des Sciences Paris, 237: 1785-1787.

Fornaciari, E. & Agnini, C., (2009). Taxonomic note: Sphenolithus pseudoheteromorphus, a new Miocene calcareous nannofossil species from the equatorial Indian Ocean. Journal of Nannoplankton Research, 30(2): 97-101.

Young, J.R., (1998). Neogene. In: Bown, P.R. (Editor), Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publications Series. Chapman & Hall, London, pp. 225-265.


Nannotax3 - Coccolithophores - Sphenolithus heteromorphus by: Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-4-2017

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Bryan C. Ladner
Just wanted to point out that the correct spelling of S. heteromorphus is as indicated just now. There is no 'os' after morph, it is simply heteromorphus. I have a PDF copy of the original description by Deflandre (1953) if you need it to confirm my comment. Thanks, Bryan Ladner
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Jeremy Young (NHM, UK)

Thanks Brian
You are quite right of course, this is something of a blind spot of mine. Anyway I have corrected it now (a moderately arkward process but easier than doing it in a non-database system).
Jeremy

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