Nannotax3 - ntax_cenozoic - Rhomboaster Nannotax3 - ntax_cenozoic - Rhomboaster


Classification: ntax_cenozoic -> Nannolith families inc sed -> Rhomboasteraceae -> Rhomboaster
Sister taxa: Rhomboaster, Tribrachiatus

Daughter taxa (time control age-window is: 0-800Ma)
Rhomboaster bramlettei
Nannolith with the appearance of two symmetrically offset and superimposed tri-radiate cycles. Three-dimensional but flatter than Rhomboaster cuspis.
Rhomboaster calcitrapa
Rhombic Rhomboaster nannoliths with long, thin extensions from the points of the rhomb.
Rhomboaster cuspis
Rhombic Rhomboaster nannoliths with little or no extensions from the points of the rhomb.
Rhomboaster sp.
Specimens which cannot be assigned to any established species


Citation: Rhomboaster Bramlette & Sullivan, 1961
Rank: Genus
Type species: Rhomboaster cuspis Bramlette & Sullivan, 1961
Synonyms: Trochastrites Stradner 1961
Taxonomic discussion: See comments for the family.

Distinguishing features:
Parent taxon (Rhomboasteraceae): Nannoliths with rhombic and tri-radiate morphologies, and non-birefringent images in XPL. Incorporating the genera Rhomboaster and Tribrachiatus.
This taxon: Solid nannoliths that include rhombic, rhombic with spinose extensions and forms composed of two superimposed tri-radiate cycles.

Farinacci & Howe catalog pages: Rhomboaster + * , Trochastrites *

Search data:
Lith size: 5->20µm; Segments: 6->6;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): in lower part of Ypresian Stage (20% up, 54.3Ma, in Ypresian stage). Data source: Total of range of species in this database
First occurrence (base): within Ypresian Stage (47.84-55.96Ma, base in Ypresian stage). Data source: Total of range of species in this database

Plot of occurrence data:


Agnini, C., Fornaciari, E., Raffi, I., Rio, D., Rohl, U. & Westerhold, T. (2007a). High-resolution nannofossil biochronology of middle Paleocene to early Eocene at ODP Site 1262: Implications for calcareous nannoplankton evolution. Marine Micropaleontology. 64: 215-248. gs

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 O

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

Stradner, H. (1961). Vorkommen von Nannofossilien im Mesozoikum und Alttertiär. Erdoel-Zeitschrift. 77(3): 77-88. gs


Rhomboaster compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 26-3-2023

Taxon Search:
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AphiaID: not found
Short stables page link: Go to to create a permanent copy of this page - citation notes

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