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Nannotax3 - ntax_main - Heliolithus Nannotax3 - ntax_main - Heliolithus

Heliolithus

Classification: ntax_main -> Discoasterales -> Heliolithaceae -> Heliolithus
Sister taxa: Heliotrochus, Bomolithus, Heliolithus, Caycedoae

Daughter taxa (time control age-window is: 0-800Ma)
				elevated column
				Heliolithus riedelii 7-11 µm - column flaring and with deep depression, disc sloping
				Heliolithus knoxii 6-15 µm - like riedelii but column parallel sided and disc flatter
				disk-like
				Heliolithus bukryi 9-15 µm rather flat, disk much wider than column; column with vertical side and central canal
				Heliolithus kolovos 10-17 µm, disk-like, column narrow. Like bukryi, but flatter
				Heliolithus magnificus 10-13 µm, disk-like, column wide. Like bukryi, but column wider
				squat, column nearly as wide as disk
				Heliolithus aktasii 6-8 µm column nearly as wide as disk, similar height, non-flaring
				Heliolithus iptamenosdiskos 6-10 µm low, disk & column of similar width, column tapers at edge & has central canal. Like aktasii but wider and lower.
				Heliolithus nefroeidis 6-10 µm, column thicker at centre ('kidney shaped')
				probably not helioliths
				Heliolithus amfivolos no evidence of V-units/column
				Heliolithus margarita no evidence of V-units/column. Possibly an isloated proximal shield
				Heliolithus sp. Specimens which cannot be assigned to any established species

Romein 1979 fig41.png

Taxonomy:

Citation: Heliolithus Bramlette & Sullivan, 1961

Taxonomic rank: genus

Type species: Heliolithus riedelii Bramlette & Sullivan, 1961

Synonyms:

Heliotrochus Aubry 2014 - genus for disk-like Heliolithus species, type species H. kleinpellii

Distinguishing features:
Parent taxon (Heliolithaceae): Discoidal discoasteralids with several distinct cycles including at least one that is birefringent.
This taxon: Two superposed cycles - weakly birefringent column and strongly birefringent disk

Farinacci & Howe catalog pages:
Heliolithus * , Heliotrochus *

Morphology:

The nanoliths are formed of two prominent superposed cycles, both of which are strongly birefringent in plan view - the disk and column. The disk is broader than the column, when viewed from the disk side the nannolith appears unicyclic and the elements show anticlockwise obliquity. When viewed from the column side both cycles are visible, the column typically has a vertical edge and does not show imbrication, both cycles show clockwise obliquity.

In well preserved specimens/with favourable orientation a third cycle is visble between these two in at least some species (notably H. cantabriae), in the EM this cycle is visible at the base of the column.

Romein (1979) used crystallographic orientation to infer origin from Fasciculithus bitectus (= Lithoptychius s.l.) and suggested that the disk was distal.

Search data:

LITHS: nannolith-radiate, circular, star-shaped, CROSS-POLARS: V-prominent, R-prominent,

Lith size: 6->18µm;

The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): at top of NP9 zone (100% up, 55.9Ma, in Ypresian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Middle Paleocene Sub-Epoch (59.24-61.61Ma, base in Selandian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
See also: customisable plot Parent: Heliolithaceae

References:

Aubry, M. -P. (2014). Cenozoic Coccolithophores: Discoasterales. Micropaleontology Press, American Museum of Natural History, New York. 1-400. gs

Bramlette, M. N. & Sullivan, F. R. (1961). Coccolithophorids and related nannoplankton of the Early Tertiary in California. Micropaleontology. 7(2): 129-188. gs

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

Heliolithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 17-6-2026

Taxon Search:

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=698 Go to Archive.is to create a permanent copy of this page - citation notes

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