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
Braarudosphaerales 2N(?) cell covered by pentaliths (plates formed of 5 segments with lamellar sub-structure) formed extracellularly N: cell motile, covered by scales
Nannolith families inc sed Haptophytes forming calcareous structures not obviously homologous with heterococcoliths, holococcoliths, or discoasteralids
Citation: Coccolithophores informaltaxonomic rank: overall groupTaxonomic discussion: Coccolithophore classification is primarily based on the calcareous coccoliths they produce. The structure and mineralogy of coccoliths is very tightly controlled during the, intracellular, coccolith-formation process and so coccolith structure has proven a remarkably robust classification tool, well supported by modern molecular-genetic data. It also means biologists and palaeontologists use the same classification.
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
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range: Last occurrence (top): at top of (100% up, 0Ma, in "Holocene" stage). Data source: Total of ranges of the species in this database First occurrence (base): within (-Ma, base in "Holocene" stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page
References:
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. gs
Cenozoic and Modern Coccolithophores compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 11-12-2023
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Zhang Wei
3
Jun 2023
Zhang Wei(China)
How many nannofossil genus and species in the Cenozoic?
Jeremy Young
508
Jan 2017
Jeremy Young(UK)
Hi
On nannotax we document 180 genera and 1232 species in the Cenozoic ... but of course some of those may be artificial, others have not been described, and there are some papers we have not synthesised yet.
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Comments (2)
How many nannofossil genus and species in the Cenozoic?
Hi
On nannotax we document 180 genera and 1232 species in the Cenozoic ... but of course some of those may be artificial, others have not been described, and there are some papers we have not synthesised yet.
Jeremy