|Daughter taxa (time control age-window is: 0-800Ma)||Granddaughter taxa|
|Holococcoliths formed from multiple blocks|
Domed cavate holococcoliths with surficial shallow pits.
Elliptical holococcoliths with perforations.
Cavate holoccoliths with distinct crystallographic blocks.
Holococcoliths with multiple elements in the central area
Holoccoliths with distinct rim and cover blocks, typically eight.
Rectangular holococcoliths formed from four thin blocks that are birefringent in XPL.
Paleogene holococcoliths usually seen in side view and comprising a thick proximal plate and spine or process, typically with a cavity or axial canal.
S. sp. cf. S. biskayae
Cavate, thin walled, box-like holococcoliths usually seen in side view.
Geometrically shaped non-birefringent holococcoliths typically possessing lateral rim spines and central area bars.
Spinose holococcoliths, which are birefringent in side view. In plan view the coccoliths are non-birefringent with a distinct figure-of-eight shaped central structure.
|Holococcoliths formed from a single block|
Unusual holococcoliths with non-coccolith morphology typically comprising an elliptical, concavo-convex, domed, perforate framework.
Discoidal holococcoliths with large central openings and marginal perforations or indentations; non-birefringent in plan view.
Single-block holococcoliths that typically have a spine or process and transverse bridge or bars.
|Unidentified fossil holococcoliths|
Taxonomic discussion: As indicated there is a significant group of fossil holococcoliths which behave as a single crystal unit, or block, in cross-polars, and typically show very low birefingence in plan view. This spearation is not perfectly refelcted in the taxonomy though as some species which show this crystallography occur in Youngilithus and Holococcolithus.
Parent taxon (Holococcoliths): Haploid life-cycle stages, with liths formed of numerous rhombohedral microcrystals
This taxon: Holococcolith genera only known from the fossil record
Farinacci & Howe catalog pages: Calyptrosphaeraceae [no catalog entry yet]
Morphology: Whilst this is a very disparate group of genera they are mostly larger than extant holococcoliths and tend to have distinctive shapes, rather than being simple discs.
|Metrics||Lith size: 0->0µm;|
Last occurrence (top): in upper part of Ionian Stage (75% up, 0.3Ma, in Ionian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Campanian Stage (0% up, 83.6Ma, in Campanian stage). Data source: Total of range of species in this database
Plot of occurrence data:
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