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): at top of NN16 zone (100% up, 2.5Ma, in Gelasian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NP4 zone (61.51-63.25Ma, base in Danian stage). Data source: Total of ranges 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 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 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 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

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

Perch-Nielsen, K. (1985). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge (1): 427-555. gs

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

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

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

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.	Sphenolithus abies Sphenolithus apoxis Sphenolithus moriformis Sphenolithus grandis Sphenolithus puniceus Sphenolithus acervus Sphenolithus primus
	Oligocene-Miocene groups
	S. heteromorphus group Late Oligocene - Early Miocene sphenoliths with apical spines formed from a single element.	Sphenolithus heteromorphus Sphenolithus milanetti Sphenolithus preasii Sphenolithus pseudoheteromorphus Sphenolithus conicus Sphenolithus calyculus
	S. delphix group	Sphenolithus belemnos Sphenolithus tintinnabulum Sphenolithus bipedis Sphenolithus delphix Sphenolithus microdelphix Sphenolithus spinula
	S. capricornutus group Apical spine formed of radiating elements	Sphenolithus capricornutus Sphenolithus cometa Sphenolithus multispinatus
	S. dissimilis group Bases cylindrical or conical, compound apical spine	Sphenolithus disbelemnos Sphenolithus dissimilis Sphenolithus procerus Sphenolithus compactus Sphenolithus truaxii
	Eocene - Oligocene groups
	S. furcatolithoides group Small Middle Eocene sphenoliths with duocrystaline spines that are dark in the 45° position.	Sphenolithus recolletensis Sphenolithus strigosus Sphenolithus furcatolithoides Sphenolithus pseudofurcatolithoides Sphenolithus perpendicularis Sphenolithus 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.	Sphenolithus pseudoradians Sphenolithus radians Sphenolithus arthurii Sphenolithus richteri Sphenolithus spiniger Sphenolithus orphanknollensis Sphenolithus editus
	S. anarrhopus group Late Paleocene and Early Eocene sphenoliths with monocrystalline spines	Sphenolithus anarrhopus Sphenolithus conspicuus Sphenolithus villae
	Sphenolithus sp. Specimens which cannot be assigned to established species