Nannotax3 - ntax_cenozoic - Sphenolithus belemnos

Sphenolithus belemnos

Classification: ntax_cenozoic -> Discoasterales -> Sphenolithaceae -> Sphenolithus -> S. delphix group -> Sphenolithus belemnos
Sister taxa: S. belemnos, S. tintinnabulum, S. bipedis, S. delphix, S. microdelphix, S. spinula


Citation: Sphenolithus belemnos Bramlette and Wilcoxon, 1967
Rank: Species

Taxonomic discussion:
This species has a well developed monolithic spine with straight extinction. It can be distinguished from other species of this type by the nature of its base. This has a tall well-developed proximal cycle, but only diminutive lateral elements, overall the base is distinctly elongate, and merges smoothly into the spine.

Distinguishing features:
Parent taxon (S. delphix group):
This taxon: Dart-shaped, apical spine well-developed. Lateral elements much smaller than proximal elements.

Farinacci & Howe catalog pages: S. belemnos *

Size: : Length 4-8 microns, width 2-4 microns.

Most likely ancestor: Sphenolithus tintinnabulum - at confidence level 3 (out of 5). Data source: Howe 2021, fig. 10.

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, CA: process, CROSS-POLARS: V-prominent, R-prominent,
MetricsLith size: 4->8µm;
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: Zone NN3 was origiinally defined by Martini (1971) as going from LAD T. carinatus to LAD S. belemnos; but in practice most workers use FAD S. belemnos to LAD S. belemnos. Where the orignal definition is followed NN3 is shown as haiving a very short duration.
Last occurrence (top): in lower part of chron C5Dr.2r sub-Magnetochron (20% up, 18Ma, in Burdigalian stage). Data source: Raffi et al. (2006), fig 5
First occurrence (base): in upper part of chron C6N sub-Magnetochron (70% up, 19Ma, in Burdigalian stage). Data source: Raffi et al. 2006, fig. 5

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

Bramlette, M. N. & Wilcoxon, J. A. (1967b). Middle Tertiary calcareous nannoplankton of the Cipero section, Trinidad, W.I. Tulane Studies in Geology and Paleontology. 5: 93-131. gs V O

de Kaenel, E. & Villa, G. (1996). Oligocene-Miocene calcareous nannofossil biostratigraphy and paleoeecology from the Iberian Abyssal Plain. Proceedings of the Ocean Drilling Program, Scientific Results. 149: 79-145. 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. (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 belemnos compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 24-9-2021

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Short stable page link: Go to to create a permanent copy of this page - citation notes

Comments (1)

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Mike Styzen (Noble Energy, US)
If you look at the photos with the original description, you will see that what is illustrated here is clearly not the same bug. In the original photos the basal cycle, immediately below the apical spine is distinctly asymmetric with one of the two elements being much smaller. In the same view (at 45 degrees to the nichols) the column shows a single dark line with 2 visible elements not the 3 seen in these photos. I've just been through this section in excruciating detail. The forms illustrated here range considerably higher than those that resemble the original illustrations. You can see the original photos in either P.N. 1985 or in the Aubry Handbook and you'll see what I mean.
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