Daughter taxa (time control age-window is: 0-800Ma)![]() | Granddaughter taxa | ||||
Heterococcoliths | |||||
Isochrysidales 2N: Mostly placolith heterococcoliths with R-unit dominant. Non-motile N: non-calcifying, motile, with vestigial haptonema. | |||||
![]() | 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 | ||||
![]() | Zygodiscales 2N: Heterococcoliths with V-units forming upper/outer cycle of imbricated elements and R-units forming basal plate and central mass of irregular elements. Usually motile N: Form holococcoliths formed of single block | ||||
![]() | Syracosphaerales 2N: Coccoliths with radial lath cycle of T-units, and disjunct, often complex, axial structure, coccospheres often polymorphic, usually motile N: Form holococcoliths, highly variable | ||||
Coccolith families inc sed 2N: Various heterococcolith groups not obviously related to the well-defined orders N: mostly unknown | Alisphaeraceae Papposphaeraceae Umbellosphaeraceae narrow rimmed placoliths Coccolith genera inc sed Unidentified heterococcoliths | ||||
Mesozoic Survivors Mesozoic taxa which occur in low abundances in the early Palaeogene. | |||||
Holococcoliths & Nannoliths | |||||
![]() | Holococcoliths Haploid life-cycle stages, with liths formed of numerous rhombohedral microcrystals | tubeless convex bridged flat-topped septate open-tube fossil holococcoliths Unidentified extant holococcolith | |||
![]() | Braarudosphaerales 2N(?) cell covered by pentaliths (plates formed of 5 segments with lamellar sub-structure) formed extracellualrly N: cell motile, covered by scales | ||||
![]() | ![]() | ![]() | ![]() | Discoasterales Radially symmetrical nannoliths formed from one to several separate cycles of elements that radiate from a common centre or axis. | |
![]() | Nannolith families inc sed Haptophytes forming calcareous structures not obviously homologous with heterococcoliths, holococcoliths, or discoasteralids |
Taxonomy:
There are complications however, most obviously, typical coccolithophores have haplo-diplontic life-cycles with different coccoliths produced in haploid and diploid phases. The diploid phase heterococcoliths have complex structures formed of radial arrays of interlocking crystal units usually with alternating vertical and radial crystallographic orientations (V/R model). The different rim-structures of these heterococcoliths form the essential basis of the classification. The haploid phase holococcoliths are beautifully organised arrays of rhombohedral crystallites, but their morphology is relatively plastic and does not yield useful phylogenetic data. Finally, some other nannofossils occur which do not obviously fit either the heterococcolith or holococcolith model and these are conventionally refered to as nannoliths.
Understanding the classification of coccolithophores thus requires some basic knowledge of coccolithophore life-cycles, biomineralisation, crystallography and optical mineralogy (to interpret cross-polarised light images). A useful overview is provided by Bown & Young (1998) and other references which help explain the system applied here are listed below.
Distinguishing features:
Parent taxon (images):
This taxon: Extant coccolithophores and Cenozoic calcareous nannofossils - Mesozoic nannofossils are in a separate module
Farinacci & Howe catalog pages: Coccolithophores [no catalog entry yet]
Search data:
Lith size: 0->0µm; |
Geological Range:
Last occurrence (top): Extant. Data source: Total of range of species in this database
First occurrence (base): at top of No known fossil record modern (100% up, 0Ma, in "Holocene" stage). Data source: Total of range of species in this database
Plot of occurrence data:
Bown, P. R. & Young, J. R. (1998a). Introduction - calcareous nannoplankton biology. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 1-15. gs Young, J. R., Didymus, J. M., Bown, P. R., Prins, B. & Mann, S. (1992). Crystal assembly and phylogenetic evolution in heterococcoliths. Nature. 356: 516-518. gs Young, J. R. et al. (1997). Guidelines for coccolith and calcareous nannofossil terminology. Palaeontology. 40: 875-912. gs Young, J. R., Davis, S. A., Bown, P. R. & Mann, S. (1999). Coccolith ultrastructure and biomineralisation. Journal of Structural Biology. 126: 195-215. gs 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. S1: 1-132. gs Young, J. R., Geisen, M. & Probert, I. (2005). A review of selected aspects of coccolithophore biology with implications for palaeobiodiversity estimation. Micropaleontology. 51(4): 267-288. gsReferences:
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Cenozoic and Modern Coccolithophores compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 9-6-2023
Short stables page link: https://mikrotax.org/Nannotax3/index.php?id=315 Go to Archive.is to create a permanent copy of this page - citation notes |
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