C. gigas group


Classification: ntax_cenozoic -> Coccolithales -> Coccolithaceae -> Coccolithus -> C. gigas group
Sister taxa: C. pelagicus group, C. formosus group, C. biparteoperculatus group, C. gigas group, C. sp.

Daughter taxa (time control age-window is: 0-800Ma)
Coccolithus gigas
Very large (~>15µm) Coccolithus-like coccolith with narrow central area crossed by broad diagonal bars.
Coccolithus hulliae
Broadly elliptical; central area width similar to shield width, spanned by conspicuous axial crossbars.
Coccolithus opdykei

Coccolithus mutatus
Very large (>14 µm) Coccolithus with wide central area and narrow, axial to slightly rotated cross bars.
Coccolithus staurion
Large to very large (7-15 µm) Coccolithus with a narrow central area and axial cross bars.

Taxonomy:

Citation: Coccolithus gigas group, sensu Bown & Newsam 2017
Rank: species group
Taxonomic discussion: C. hulliae was not included in this group by Bown & Newsam (2017) in order to draw attention to the fact that there is a distinctive group of larger coccoliths with crossbars in the mid Eocene. However, for practical purposes it is convenient to include, since it overlaps in range, size and morphology with the other members of the group. [my interpretation - JRY 2017]

Distinguishing features: Large to very large; central areas narrow to moderately-wide, with crossbars that are conspicuous in LM.

Farinacci & Howe catalog pages:


Morphology: Large to very large Coccolithus coccoliths with narrow to moderately-wide central areas spanned by crossbars that are conspicuous in light microscope.
Remarks: These coccoliths have previously been variously classified within the genera Cruciplacolithus, Chiasmolithus and Coccolithus but appear to represent a coherent lineage with stratigraphic range restricted to the mid-part of the Eocene (Zones 14–16). The inclusion of these species within the genus Coccolithus is consistent with the extant Coccolithus species, which can also produce central area bars and crosses.
Included species: C. gigas, C. mutatus, C. opdykei, C. staurion. [Bown& Newam 2017]

See also: Cruciplacolithus ;Coccolithus tenuiforatus ;

Search data:
TagsLITHS:
MetricsLith size: 6->24µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): in upper part of Lutetian Stage (74% up, 42.9Ma, in Lutetian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Thanetian Stage (62% up, 57.2Ma, in Thanetian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P. R. & Newsam, C. (2017). Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411). Journal of Nannoplankton Research. 37(1): 25-60. gs V O


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C. gigas group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-2-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=167 Go to Archive.is to create a permanent copy of this page - citation notes



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