|Daughter taxa (time control age-window is: 0-800Ma)||Granddaughter taxa|
|Genera with open central area (or very delicate cross)|
Eliptical or circular; central area usually open, may have with simple bar or weak axial cross
Coccoliths ring-shaped without discrete shields
Coccolithus-like coccoliths that are typically circular and have broad upper tube elements that dominate the distal shield. The dominance of the R-unit cycle results in a bright LM XPL image that is distinct from Coccolithus.
|Genus with bridge|
Rim narrow and central area spanned by an elevated bridge
|Genera with central cross|
Coccolith central area spanned by disjunct axial cross that may be rotated by up to 20 degrees.
Eocene lineage of large to extremely large Cruciplacolithus-like coccoliths
Like Cruciplacolithus but the coccoliths are longitudinally arched and typically near parallel sided, and so appear oblong in outline
Like Cruciplacolithus but coccoliths small and with large, thin, paddle-like processes.
Placolith coccoliths with Coccolithus-type shields and tube, but with disjunct diagonal cross bars spanning the central area.
|Genera with central grill or plate|
Central area covered by perforate plate which appears uniformly dark in xpl
Rim structure like Coccolithus; perforate plate covers the central area on the distal side
Placolith coccoliths with a wide central-area typically spanned by multi-element lattice-like grills or imperforate plates.
Placolith coccoliths showing low birefringence with central area filled by 2 to 4 plates. Lacks a clearly birefringent distal tube cycle
Placolith coccoliths, typically small (c. 3 microns), with central-area spanned by a finely perforate net. The distal shield is typically bicyclic and the rim structure appears to be coccolithacean.
Parent taxon (Coccolithales): 2N: Mostly placolith heterococcoliths with V-unit forming the distal shield; R-unit the proximal shield. Non-motile
N: Form holococcoliths formed of single block, or non-calcifying
This taxon: 2N: cells non-motile, bearing placoliths with R-unit extending from proximal shield to form upper/inner tube-cyle, mostly elliptical
N: cells motile, holococcolith-bearing
Farinacci & Howe catalog pages: Coccolithaceae [no catalog entry yet]
Morphology: Heterococcoliths are placoliths with rim structure similar to Coccolithus: V-unit forms both distal shield and lower cycle of central-area; R-unit forms both proximal shield and upper cycle of central-area. The proximal shield itself is bicyclic with distinct upper and lower layers but these are both formed from the R-unit. The central-area is often spanned by disjunct structures and these are used to define various fossil genera (see e.g. Perch-Nielsen 1985, Young & Bown 1997,Young & Henriksen 2003).
Biology & life-cycles: Modern Coccolithus pelagicus has a holococcolith stage
|Metrics||Lith size: 8->12µm;|
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): at base of Danian Stage (0% up, 66Ma, in Danian stage). Data source: Total of range of species in this database
Plot of occurrence data:
Perch-Nielsen, K. (1985a). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs Poche, F. (1913). Das System der Protozoa. Archiv für Protistenkunde. 30: 125-321. gs Young, J. R. & Henriksen, K. (2003). Biomineralization within vesicles: the calcite of coccoliths. Reviews in Mineralogy and Geochemistry. 54(1): 189-215. gs
Perch-Nielsen, K. (1985a). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs
Poche, F. (1913). Das System der Protozoa. Archiv für Protistenkunde. 30: 125-321. gs
Young, J. R. & Henriksen, K. (2003). Biomineralization within vesicles: the calcite of coccoliths. Reviews in Mineralogy and Geochemistry. 54(1): 189-215. gs
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