Nannotax3 - ntax_cenozoic - Sphenolithus conicus

Sphenolithus conicus


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

Taxonomy:

Citation: Sphenolithus conicus Bukry, 1971
Rank: Species

Distinguishing features:
Parent taxon (S. heteromorphus group): Late Oligocene - Early Miocene sphenoliths with apical spines formed from a single element.
This taxon: Large, coarsely constructed with high, gently tapering base and short tapering spine that is dark at 0° and bright at 45°.

Farinacci & Howe catalog pages: S. conicus *


Morphology: Similar to S. moriformis but with a small apical spine.
Also similar to S. heteromorphus but spine smaller. 


Size: Length given as 7-12 µm in the original descrition but this seems exagerrated and similar problems affect other species described in the same publication. Size range of 5-10 µm is generally seen. Bergen et al. (2017) suggest it ranges down to 4.5µm, but that larger specimens are more distinctive.

Most likely ancestor: Sphenolithus apoxis - at confidence level 3 (out of 5). Data source: Howe 2021 fig8.
Likely descendants: Sphenolithus calyculus; Sphenolithus preasii; plot with descendants

Search data:
TagsLITHS: nannolith-radiate, circular, cylindrical, CA: process, CROSS-POLARS: R-prominent,
MetricsLith size: 5->10µm;
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: Bergen et al. 2017 record large forms (>7 µm) as having a shorter range than smaller ones - with LAD at the end of NN2.
Last occurrence (top): within NN3 zone (17.95-19.00Ma, top in Burdigalian stage). Data source: Bergen et al. 2017
First occurrence (base): within NP24 zone (26.84-29.62Ma, base in Rupelian stage). Data source: Bergen et al. 2017

Plot of occurrence data:

References:

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

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

Dunkley Jones, T., Bown, P. R. & Pearson, P. (2009). Exceptionally well preserved upper Eocene to lower Oligocene calcareous nannofossils (Prymnesiophycidae) from the Pande Formation (Kilwa Group), Tanzania. Journal of Systematic Palaeontology. 7(4): 359-411. gs

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

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

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


nannotaxlogo400px

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

Taxon Search:
Advanced Search

Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1291 Go to Archive.is to create a permanent copy of this page - citation notes



Comments (0)

No comments yet on this page. Please do add comments if you spot any problems, or have information to share

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics