Nannotax3 - ntax_cenozoic - ntax_cenozoic

Cenozoic and Modern Coccolithophores


Classification: ntax_cenozoic
Sister taxa:

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.
Noelaerhabdaceae
Prinsiaceae
Isochrysidaceae

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
Coccolithaceae
Calcidiscaceae
Hymenomonadaceae
Pleurochrysidaceae

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
Helicosphaeraceae
Pontosphaeraceae
Zygodiscaceae

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
Calciosoleniaceae
Rhabdosphaeraceae
Syracosphaeraceae

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
U. heterococcoliths

Mesozoic Survivors
Mesozoic taxa which occur in low abundances in the early Palaeogene.
Biscutaceae
Chiastozygaceae
Markalius
Watznaueriaceae

Holococcoliths & Nannoliths
Holococcoliths
Haploid life-cycle stages, with liths formed of numerous rhombohedral microcrystals
tubeless
convex
bridged
flat-topped
septate
open-tube
fossil holococcoliths
U. 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
Braarudosphaeraceae

Discoasterales
Radially symmetrical nannoliths formed from one to several separate cycles of elements that radiate from a common centre or axis.
Discoasteraceae
Fasciculithaceae
Heliolithaceae
Sphenolithaceae

Nannolith families inc sed
Haptophytes forming calcareous structures not obviously homologous with heterococcoliths, holococcoliths, or discoasteralids
Ceratolithaceae
Lapideacassaceae
Lithostromationaceae
Nannolith genera inc sed
Rhomboasteraceae

Taxonomy:

Citation: Coccolithophores informal
Rank: overall group

Taxonomic 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

Farinacci & Howe catalog pages: Coccolithophores [no catalog entry yet]

Search data:
TagsLITHS:
MetricsLith size: 0->0µm;
The morphological data given here can be used on the advanced search page. See also these notes

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:

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. (1991a). 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 V O

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, Special Issue. 1: 1-132. gs V O

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


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Cenozoic and Modern Coccolithophores compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-10-2021

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Short stable 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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