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 |
Taxonomy:
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; |
Geological Range:
Last occurrence (top): at top of NP10 zone (100% up, 54.2Ma, in Ypresian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NP9 zone (55.86-57.21Ma, base in Thanetian stage). Data source: Total of ranges 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 OReferences:
Rhomboaster compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 6-10-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1202 Go to Archive.is to create a permanent copy of this page - citation notes |
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