Rarer genera


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

Distinguishing features: Less common genera


Daughter taxa: (blue => in age window 0-800Ma) Granddaughter taxa
Disk-shaped holococcoliths
Bifidalithus
Holococcoliths formed from two blocks divided by a transverse suture.

Bilapillus
Holococcolith with narrow rim and two blocks in central area

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

Munarinus
Holococcoliths formed from 4-12 blocks with central-area filled or spanned by disjunct bar or block.

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

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

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

Pharus
Elliptical coccolith formed of a single block, with two perforations

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

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

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

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

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

Duocameratus
Cavate holococcolith with central septum

Lacunolithus-Bown


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

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

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

Petrobrasiella
Domed-shaped holococcoliths with holes or cavities.

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

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

Stereorhabdus
Holoccolith with elliptical base and five-rayed process

Tanzanella
Cavate holococcolith with internal walls and distal protrusions

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

unidentified holococcoliths


Taxonomy:

Rank: informal group of genera

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

Distinguishing features: Less common genera

Search data:
TagsLITHS: holococcolith,
MetricsLith size: 0->0┬Ám;
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 Thanetian Stage (100% up, 56Ma, in Thanetian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Toarcian Stage (0% up, 182.7Ma, in Toarcian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:


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Rarer genera compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 3-12-2020

Taxon Search:
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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10985 Go to Archive.is to create a permanent copy of this page - citation notes



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