Nannotax3 - ntax_cenozoic

Citation: Sphenolithus Deflandre in Grassé, 1952

Type species: Sphenolithus radians Deflandre in Grassé, 1952

Synonyms:

Sphenaster Wilcoxon, 1970
Nannoturbella Brönnimann & Stradner 1960

Taxonomic discussion: More than 40 species of Sphenolithus have been described. We subdivide them here into informal groups which we believe represent clusters of closely related species, or in some cases single morphologically variable species. The primary criteria are the nature of the spine which may be barely developed (moriformis group), formed of numerous elements (radians group), two elements (predistentus and furcatolithoides groups), or a single element (conspicuus and heteromorphus groups). In addition the base may be formed of several cycles of elements (most groups) or only one cycle (predistentus group).
There has been a tendency toward recognition of ever more sphenolith "species", but it is by no means clear that these reflect biological species, as discussed by Towe (1979).
See also - Perch-Nielsen 1985; Aubry 1989; Maiorano & Monechi 1997; Shamrock 201; Bergen et al. 2017; Howe 2021

Distinguishing features:
Parent taxon (Sphenolithaceae): Conical discoasteralids with a concave base, consisting of a mass of elements radiating from a common origin.
This taxon: Conical nannoliths with a concave base, consisting of a mass of elements radiating from a common origin.

Geological Range:
Last occurrence (top): near base of Piacenzian Stage (14% up, 3.5Ma, in Piacenzian stage). Data source: Total of range of species in this database
First occurrence (base): near top of Danian Stage (90% up, 62.1Ma, in Danian stage). Data source: Total of range of species in this database

References:

Aubry, M. -P. (1989a). Handbook of Cenozoic calcareous nannoplankton. Book 3: Ortholithae (Pentaliths, and others), Heliotithae (Fasciculiths, Sphenoliths and others). Micropaleontology Press, American Museum of Natural History, New York. 1-279. gs

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. (1952). Classe des Coccolithophoridés. (Coccolithophoridae. Lohmann, 1902). In, Grassé, P. P. (ed.) Traité de Zoologie. Masson, Paris 439-470. gs

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

Maiorano, P. & Monechi, S. (1997). New Early Miocene species of Sphenolithus Deflandre, 1952 from the North Atlantic Ocean. Journal of Nannoplankton Research. 19(2): 103-107. gs V O

Martini, E. (1965). Mid-Tertiary calcareous nannoplankton from Pacific deep-sea cores. Colston Papers. 17: 393-411. gs

Perch-Nielsen, K. (1985a). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs

Romein, A. J. T. (1979). Lineages in Early Paleogene calcareous nannoplankton. Utrecht Micropaleontological Bulletin. 22: 1-231. gs V O

Towe, K. M. (1979). Variation and systematics in calcareous nannofossils of the genus Sphenolithus. American Zoologist. 19: 555-572. gs

Wilcoxon, J. A. (1970b). Sphenaster new genus, a Pliocene calcareous nannofossil from the tropical Indo-Pacific. Tulane Studies in Geology and Paleontology. 8: 78-81. gs V O

Comments (1)

Page 1 of 1

Kenneth M. Towe (Smithsonian Institution emeritus, US)

This old paper should be added to the list of references...

1979 K.M. Towe, Variation and systematics in calcareous nannofossils of the genus Sphenolithus. AMERICAN ZOOLOGIST, v. 19, p. 555-572.

It should give pause to the discussion of various "species" in this genus.

20th December 2015 2:03pm

Jeremy Young (UCL, UK)

good point - do you have a pdf copy of the paper. it would be nice to include your reconstruction of sphenolithus sphere.

21st December 2015 6:43pm

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moriformis group ranges from Paleocene to Pliocene, the other groups are arranged in age sequence (time control age-window is: 0-800Ma)		Granddaughter taxa
	S. moriformis group Conical and hemispherical sphenoliths without prominent apical spines.	S. abies S. apoxis S. moriformis S. grandis S. puniceus S. acervus S. primus
	Oligocene-Miocene groups
	S. heteromorphus group Late Oligocene - Early Miocene sphenoliths with apical spines formed from a single element.	S. heteromorphus S. milanetti S. preasii S. pseudoheteromorphus S. conicus S. calyculus
	S. delphix group	S. belemnos S. tintinnabulum S. bipedis S. delphix S. microdelphix S. spinula
	S. capricornutus group Apical spine formed of radiating elements	S. capricornutus S. cometa S. multispinatus
	S. dissimilis group Bases cylindrical or conical, compound apical spine	S. disbelemnos S. dissimilis S. procerus S. compactus S. truaxii
	Eocene - Oligocene groups
	S. furcatolithoides group Small Middle Eocene sphenoliths with duocrystaline spines that are dark in the 45° position.	S. recolletensis S. strigosus S. furcatolithoides S. shamrockiae S. perpendicularis S. kempii
	S. radians group Eocene to Early Oligocene sphenoliths with compound spines, that are visible but dim at 0° and brightest when at 45° to the polarizing directions.	S. pseudoradians S. radians S. arthurii S. richteri S. spiniger S. orphanknollensis S. editus
	S. anarrhopus group Late Paleocene and Early Eocene sphenoliths with monocrystalline spines	S. anarrhopus S. conspicuus S. villae
	Sphenolithus sp. Specimens which cannot be assigned to established species

Tags	LITHS: nannolith-radiate, circular, cylindrical, CROSS-POLARS: R-prominent,
Metrics	Lith size: 4->20µm;

Sphenolithus

References:

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