Nannotax3 - ntax_mesozoic - Rarer genera Nannotax3 - ntax_mesozoic - Rarer genera

Rarer genera

Classification: ntax_mesozoic -> Holococcoliths -> Rarer genera
Sister taxa: Common genera, Rarer genera

Distinguishing features:
Parent taxon (Holococcoliths): Coccoliths formed of minute (ca 0.1µm) rhombohedral micro-crystals. Often a life-cycle stage with heterococcolith counterpart(s).
This taxon: Less common genera

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
Disk-shaped holococcoliths
Holococcoliths formed from two blocks divided by a transverse suture.
Bifidalithus geminicatillus
Bifidalithus mchanae
Bifidalithus sp.

Holococcolith with narrow rim and two blocks in central area
Bilapillus wadeae
Bilapillus sp.

Holococcoliths formed from ~7 triangular blocks with irregular blocks in the central-area.
Multipartis ripliensis
Multipartis sp.

Holococcoliths formed from 4-12 blocks with central-area filled or spanned by disjunct bar or block.
Munarinus keadyi
Munarinus lesliae
Munarinus marszalekii
Munarinus mkeremei
Munarinus sp.

Holococcolith formed of 8 blocks, typically 4 large and 4 small.
Octolithus multiplus
Octolithus sp.

Elliptical holococcolith with broad rim of numerous small blocks and central area of two or more blocks
Okkolithus australis
Okkolithus sp.

Elliptical holococcolith with rim of multiple small elements, central are open except for bridge across short axis.
Ottavianus giannus
Ottavianus terrazetus
Ottavianus sp.

Elliptical coccolith formed of a single block, with two perforations
Pharus clarescopoli
Pharus simulacrum
Pharus sp.

Holococcoliths with rim of 12-14 blocks and central-area spanned by a narrow, dark bar.
Ramsaya swanseana

Holococcoliths with rim of 10-26 blocks and a small central block.
Russellia bukryi
Russellia laswellii
Russellia sp.

Holococcoliths with rim formed from 8-12 elements, and 2 longitudinally-oriented elongate blocks in the central-area.
Saepiovirgata biferula
Saepiovirgata sp.

Other forms - mostly cavate
Holococcoliths with a proximal plate of three blocks and tall, tapering spines.
Acuturris scotus
Acuturris sp.

Elliptical, cavate (and usually septate) holococcoliths, often bearing hollow spines. Distal surfaces may be perforate and there may be internal buttresses.
Anfractus harrisonii
Anfractus parvus
Anfractus variabilis
Anfractus youngii
Anfractus sp.

Cavate holococcolith with central septum
Duocameratus leariae
Duocameratus sianiae
Duocameratus sp.


Lacunolithus tholiformis

Cavate, conical-flask shaped holococcolith with lid and internal partition.
Metadoga ampulla
Metadoga mercurius
Metadoga sp.

Conical shaped holococcolith, usually seen in side view, base weak or absent
Nicholasia baileyi
Nicholasia sp.

Cavate holococcoliths with thin rims and small spines; whole holococcolith behaves as a single crystal in xpl,
Paulpearsonia ecclesiata
Paulpearsonia sp.

Domed-shaped holococcoliths with holes or cavities.
Petrobrasiella venata
Petrobrasiella sp.

Solid, truncated-cone-shaped nannolith with rectangular cross-section constructed from minute, roughly equidimensional crystallites. Possibly a holococcolith.
Pseudoconus enigma
Pseudoconus sp.

Holococcoliths usually seen in side view and comprising a thick proximal plate and spine or process, typically with a cavity or axial canal.
Semihololithus bicornus
Semihololithus priscus
Semihololithus sp.

Holoccolith with elliptical base and five-rayed process
Stereorhabdus pentaculum
Stereorhabdus sp.

Cavate holococcolith with internal walls and distal protrusions
Tanzanella bownii
Tanzanella sp.

Cavate holococcolith with box-shape, high rim and thin proximal plate, short spine on distal surface
Thecatus varolii
Thecatus sp.

unidentified holococcoliths


taxonomic rank: informal group of genera
Taxonomic discussion: It is only possible to definitively identify holococcoliths from elctron microscopy images of very well-preerved material. Possible holococcoliths include Zebrashapka

Farinacci & Howe catalog pages: Rarer genera [no catalog entry yet]

Distinguishing features:
Parent taxon (Holococcoliths): Coccoliths formed of minute (ca 0.1µm) rhombohedral micro-crystals. Often a life-cycle stage with heterococcolith counterpart(s).
This taxon: Less common genera

Search data:
: holococcolith,
Lith size: 0->0µm;
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 Paleocene Epoch (100% up, 56Ma, in Thanetian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Toarcian Stage (174.70-184.20Ma, base in Toarcian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:



Rarer genera compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-6-2024

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

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