Coronocyclus


Classification: Coccolithophores -> Coccolithales -> Coccolithaceae -> Coronocyclus
Sister taxa: Coccolithus, Bramletteius, Campylosphaera, Chiasmolithus, Coronocyclus, Cruciplacolithus, Ericsonia, Solidopons, Birkelundia, Clausicoccus, Craticullithus, Hughesius, Kilwalithus,

Daughter taxa: (blue => in age window 0-800Ma) Granddaughter taxa
Ring-shaped coccoliths with open central-area. No clear shield development, spines on distal side. Strongly birefringent.

Ellptical Coronocyclus with  wide central area and narrow to broad shield.

Elliptical Coronocyclus species, with narrow rim

Very large species of Coronocyclus

Specimens which cannot be assigned to established species

Taxonomy:

Citation: Coronocyclus Hay Mohler & Wade 1966
Rank: Genus
Type species: Coronocyclus serratus Hay Mohler & Wade 1966 (subjective junior synonym ofC. nitescens Kamptner 1963)
Notes & discussion: One possible interpretation of the coccolith morphology is that it evolved from a Coccolithus type placolith by reduction of the shields.

Distinguishing features: Coccoliths ring-shaped without discrete shields

Farinacci & Howe catalog pages: Coronocyclus + *


Morphology remarks: Ring shaped coccoliths without discrete shields. Bright between cross-polars. Formed of two cycles of elements. An inner (usually spinose) cycle of R-units is imbricate and wraps around the outer cycle of non-imbricate V-units.

Search data:
TagsLITHS: placolith, circular, sub-circular, RIM: rim-narrow, rim-edge serrated, CA: vacant,
CSPH: spherical, equant, monomorphic, V-UNITS: distal shield, px-tube, V-prominent, R-UNITS: ds-tube, prox shield, R-prominent, DETAILS: rim-bicyclic, isogyres oblique,
MetricsLith size: 4->12µm;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: First occurrence from Perch-Nielsen 1985
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 lower part of Lutetian Stage (23% up, 46.3Ma, in Lutetian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P. R., Dunkley-Jones, T. & Young, J. R. (2007). Umbilicosphaera jordanii Bown 2005 from the Paleogene of Tanzania: confirmation of generic assignment and a Paleocene origination for the family Calcidiscaceae. Journal of Nannoplankton Research. 29(1): 25-30. gs :: view :: open

Hay, W. W., Mohler, H. P. & Wade, M. E. (1966). Calcareous nannofossils from Nal'chik (northwest Caucasus). Eclogae Geologicae Helvetiae. 59: 379-399. gs :: view :: open


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Coronocyclus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 8-8-2020

Taxon Search:
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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=355 Go to Archive.is to create a permanent copy of this page - citation notes



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