flat-topped


Ancestry: Coccolithophores -> Holococcoliths -> flat-topped
Sister taxa: tubeless, convex, bridged, flat-topped, septate, open-tube, fossil holococcoliths,

Short diagnosis: Holococcoliths with tube, covered distally by a flat cover


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Monomorphic - cavate
Coccoliths with broad rim and recessed distal cover without boss

Dimorphic - usually cavate
BCs with flat distal cover with or without openings; central boss
CFCs; with irregular bridge or distal cover arched upwards

Monomorphic; liths solid - formed of layers of crystallites in rhomboid array
Coccolith distal surface with central boss and varying number of depressions.

Dimorphic - liths cavate
BCs flat topped with large openings in tube and variable openings in distal surface; tiered wall fabric; low transverse ridge.
CFCs helladoliths - ridge of BCs is extended into prominent leaf, no openings in tube.

Dimorphic; liths semi-solid - formed of concentric rings of crystallites.
BCs flat topped with node or ridge on distal surface, rather than a true bridge.
CFCs similar with transverse bridge or leaf.

Taxonomy:

Citation: Holococcoliths with flat cover over the tube - informal grouping proposed by Young et al., 2003
Rank: informal grouping

Farinacci & Howe catalog pages:

Short diagnosis: Holococcoliths with tube, covered distally by a flat cover

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): within Gelasian Stage (1.81-2.59Ma, base in Gelasian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Young, J.R.; Geisen, M.; Cros, L.; Kleijne, A.; Probert, I. & Ostergaard, J.B., (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research, Special Issue, 1: 1-132.


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flat-topped compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-8-2017

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