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Bomolithus

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

Daughter taxa (time control age-window is: 0-800Ma)
				Bomolithus elegans 5-8 µm; column high and conical (tapering from the disc)
				Bomolithus universus 6-11 µm; column wide wide with flaring sides and deep depression
				Bomolithus cantabriae 8-15 µm; column low and flat, with central depression
				Bomolithus dydimolofous 7-11 µm; column low and rounded
				Tonromeinia?
				Bomolithus falklandensis 7-11 µm; column low, with wide central opening
				Bomolithus sp. Specimens which cannot be assigned to any established species

Taxonomy:

Citation: Bomolithus Roth, 1973

Taxonomic rank: genus

Type species: Bomolithus elegans Roth, 1973.

Taxonomic discussion:

The nme Bomolithus was rather loosely applied to heliolithids with, in plan view in xpl, a dark outermost cycle and strongly birifrengent inner part. Bowman & Varol (2021) and Varol (2023) have shown that this grouping included nannoliths with very different structures inlcuding:

Species retained in Bomolithus whch have 3 stacked cycles
Species transferred to Cacedoae which have 2 stacked cycles
Species transfered to the Candeodiscoaster/Carlamuelleria group which have a disk of V-untis surrounding a core of R-units
A species now shown to be a placloith and placed in the Caclidiscaceae

The genus Discoasteroides Bramlette & Sulivan 1961 was used at one time for many of these species. However, the type species D. kuepperi is a regular discoaster. See also discussion in Young & Bown 2014 (p.42).

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

Farinacci & Howe catalog pages:
Bomolithus *

Search data:

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

Lith size: 5->12µm;

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 NP9b subzone (100% up, 55.9Ma, in Ypresian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NP5 zone (59.54-61.51Ma, 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:

Bown, P. R. (2010). Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14). Journal of Nannoplankton Research. 31(1): 11-38. gs O

Roth, P. H. (1973). Calcareous nannofossils: Leg 17 of the Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project. 17: 695-795. gs O

Young, J. R. & Bown, P. R. (2014). Some emendments to calcareous nannoplankton taxonomy. Journal of Nannoplankton Research. 33(1): 39-46. gs

Bomolithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-7-2026

Taxon Search:

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=136 Go to Archive.is to create a permanent copy of this page - citation notes

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