Nannotax3 - ntax_cenozoic - Sphenolithus heteromorphus

Sphenolithus heteromorphus

Classification: ntax_cenozoic -> Discoasterales -> Sphenolithaceae -> Sphenolithus -> S. heteromorphus group -> Sphenolithus heteromorphus
Sister taxa: S. heteromorphus, S. milanetti, S. preasii ⟩⟨ S. pseudoheteromorphus, S. conicus, S. calyculus


Citation: Sphenolithus heteromorphus Deflandre 1953
Rank: Species

Taxonomic 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.

Distinguishing features:
Parent taxon (S. heteromorphus group): Late Oligocene - Early Miocene sphenoliths with apical spines formed from a single element.
This taxon: Apical spine very well-developed. Lateral elements nearly as large as proximal elements.

Farinacci & Howe catalog pages: S. heteromorphus *

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

Most likely ancestor: Sphenolithus pseudoheteromorphus - at confidence level 3 (out of 5). Data source: Howe 2021 fig8.

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, CA: process, CROSS-POLARS: V-prominent, R-prominent,
MetricsLith size: 6->20µm;
Data source notes: lith height from illustrated specs
The morphological data given here can be used on the advanced search page. See also these notes

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:


Bergen, J. A., de Kaenel, E., Blair, S. A., Boesiger, T. M. & Browning, E. (2017). Oligocene-Pliocene taxonomy and stratigraphy of the genus Sphenolithus in the circum North Atlantic Basin: Gulf of Mexico and ODP Leg 154. Journal of Nannoplankton Research. 37(2-3): 77-112. gs V O

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

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. gs V O

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. gs V O

Howe, R. (2021). Ultrastructure and taxonomy of the family Sphenolithaceae. Journal of Nannoplankton Research. 39(1): 29-75. gs

Maiorano, P. & Monechi, S. (1998). Revised correlations of early and middle Miocene calcareous nannofossil events and magnetostratigraphy from DSDP Site 563 (North Atlantic Ocean). Marine Micropaleontology. 35(235-255): -. gs

Perch-Nielsen, K. (1972b). Remarks on Late Cretaceous to Pleistocene coccoliths from the North Atlantic. Initial Reports of the Deep Sea Drilling Project. 12: 1003-1069. 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

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

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gs V O


Sphenolithus heteromorphus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-9-2021

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Comments (1)

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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
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).

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