Classification: Coccolithophores -> Nannolith families inc sed -> Ceratolithaceae -> Triquetrorhabdulus
Sister taxa: Amaurolithus, Ceratolithus, Nicklithus, Orthorhabdus, Triquetrorhabdulus,

Daughter taxa: (blue => in age window 0-800Ma)
Elongate (up to 50µm). All three blades identical, without ridges.
Short broad species with two wide blades bearing one to four subsidiary ridges parallel to a shorted median lath. Optic axis parallel to length.
A thin (<2µm), elongate (>25µm) species of Triquetrorhabdulus
Short (8-15µm), broad (5-8µm) species of Triquetrorhabdulus with curved sides. All blades similar.
Specimens which cannot be assigned to established species


Citation: Triquetrorhabdulus Martini 1965 emend Young & Bown 2014
Rank: Genus
Type species: Triquetrorhabdulus carinatus Martini 1965
Notes & discussion: This genus was emended by Young & Bown (2014) and species with c-xes perpendicular to the length of the nannolith were transferred to Orthorhabdus.

Distinguishing features: Elongate, tri-radiate nannoliths formed of a single calcite crystal with the c-axis parallel to the length of the nannolith. Nannolith straight with bilateral or trilateral symmetry. Shows high birefringence.

Farinacci & Howe catalog pages: Triquetrorhabdulus + *

Evolution & Phylogeny: The species included in the genus have similar morphologies and overlapping ranges.

Search data:
TagsLITHS: nannolith-other, rod-shaped,
CSPH: not known, R-UNITS: R-prominent, DETAILS: 1ou, length-fast,
MetricsLith size: 8->50µm; Segments: 3->3;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): near top of Serravallian Stage (87% up, 11.9Ma, in Serravallian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Rupelian Stage (74% up, 29.6Ma, in Rupelian stage). Data source: Total of range of species in this database

Plot of occurrence data:


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

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

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gs


Triquetrorhabdulus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-2-2020

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Short stable page link: Go to to create a permanent copy of this page - citation notes

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