Nannotax3 - ntax_cenozoic - Sphenolithus delphix

Sphenolithus delphix

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


Citation: Sphenolithus delphix Bukry 1973
Rank: Species
Synonyms: Sphenolithus spp 1 & 2 Müller 1974a, pl. 4/3-8, 19/15-16.

Taxonomic discussion:
This is the most common of a group of rather delicate spinose sphenoliths. The other described species are S. capricornutus and S. calyculus, and the more recently described variants S. microdelphix and S. spinula. They have all primarily been reported from zones NP25 and NN1.

Distinguishing features:
Parent taxon (S. delphix group):
This taxon: Large (>8µm) sphenolith with single long apical spine and flaring proximal cycle.

Farinacci & Howe catalog pages: S. delphix *

Morphology: The flaring proximal cycle giving an almost Y-shaped profile is the distinctive feature of this species and even if it is not perfecty developed in all specimens there are usually some very clear examples in an assemblage.

Size: Described as 8 to 12 microns long (Bukry 1973), but smaller specimens with similar morphology also occur.

Most likely ancestor: Sphenolithus microdelphix - 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: 5->12µm;
Data source notes: lith height from OD and illustrated specs
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Raffi (1999) documents in considerable detail restricted occurrence of S. delphix in a narrow interval calibrated from several sites against magnetochronology.  Bergen et al. (2017) however record a significantly longer range (24.7-23.1 Ma) even though they confine the definition to forms >8µm.
Last occurrence (top): in upper part of chron C6Cn.2r sub-Magnetochron (80% up, 23.1Ma, in Chattian stage). Data source: Raffi et al. 2006, fig. 5; Raffi 1999
First occurrence (base): near base of chron C6Cn.3n sub-Magnetochron (10% up, 23.3Ma, in Chattian stage). Data source: Raffi et al. 2006, fig. 5; Raffi 1999

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

Bukry, D. (1973c). Coccolith stratigraphy, eastern equatorial Pacific, Leg 16, Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project. 16: 653-711. 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

Müller, C. (1974b). Calcareous nannoplankton, Leg 25 (Western Indian Ocean). Initial Reports of the Deep Sea Drilling Project. 25: 579-633. gs V O

Raffi, I. (1999). Precision and accuracy of nannofossil biostratigraphic correlation. Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 357: 1975-1993. gs

Raffi, I. et al. (2006). A review of calcareous nannofossil astrobiochronology encompassing the past 25 million years. Quaternary Science Reviews. 25: 3113-3137. gs

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


Sphenolithus delphix compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 21-9-2021

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