Classification: Coccolithophores -> Coccolithales -> Calcidiscaceae -> Calcidiscus
Sister taxa: Calcidiscus, Hayaster, Oolithotus, Umbilicosphaera, Cryptococcolithus, Hayella,

Daughter taxa: (blue => in age window 0-800Ma) Granddaughter taxa
Circular, sub-circular and broadly-eliptical calcidiscid coccoliths with closed central-area.

Medium-sized Eocene calcidiscid coccoliths with narrow or closed central-area.

Specimens which cannot be assigned to established species


Citation: Calcidiscus Kamptner, 1950
Rank: Genus
Type species: Calcidiscus quadriforatus Kamptner 1950 (subj. j. syn. of C. leptoporus).
Notes & discussion: Species-level taxonomy:
Calcidiscus is common throughout the Neogene and shows significant variaton in size, number of elements, opening of central area, and structural details. Species concepts have been extensively discussed, most notably by Knappertsbusch (2000). Recent research has lead to a three-fold divsion of the extant Calcidiscus population, see e.g. Quinn et al. (2004), Young et al. (2003): By comparison Pliocene Calcidiscus assemblages are usually classified into: It is not sure how these species relate to the extant species but the degree of variation shown in fossil assemblages suggests that many more speces could probably be recognised.

Distinguishing features: Circular or sub-circular; central area closed or with narrow opening

Farinacci & Howe catalog pages: Calcidiscus + * , Cyclococcolithina * , Cyclococcolithus * , Cycloperfolithus * , Striatococcolithus * , Tiarolithus *

Morphology remarks: Coccoliths circular to sub-circular. Proximal shield, birefringent, distal shield non-birefringent with curved sutures. Shields easily separated.

Search data:
TagsLITHS: placolith, circular, sub-circular, RIM: rim-broad, CA: Placoliths: closed-----, closed,
CSPH: spherical, equant, monomorphic, V-UNITS: distal shield, tube, V-prominent, R-UNITS: prox shield, R-prominent, DETAILS: isogyres oblique, rim-unicyclic,
MetricsLith size: 3->14µm;
Sources: RCC
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): in upper part of Thanetian Stage (62% up, 57.2Ma, in Thanetian stage). Data source: Total of range of species in this database

Plot of occurrence data:


Bown, P. R., Dunkley-Jones, T. & Young, J. R. (2007). Umbilicosphaera jordanii Bown 2005 from the Paleogene of Tanzania: confirmation of generic assignment and a Paleocene origination for the family Calcidiscaceae. Journal of Nannoplankton Research. 29(1): 25-30. gs

Kamptner, E. (1950). Über den submikroskopischen Aufbau der Coccolithen. Anzeiger. Österreichische Akademie der Wissenschaften. Mathematische-Naturwissenschafliche Klasse. Wien. 87: 152-158. gs

Kamptner, E. (1954). Untersuchungen über den Feinbau der Coccolithen. Anzeiger. Österreichische Akademie der Wissenschaften. Mathematische-Naturwissenschafliche Klasse. Wien. 87: 152-158. gs

Kamptner, E. (1963). Coccolithineen-Skelettreste aus Tiefseeablagerungen des Pazifischen Ozeans. Annalen des Naturhistorischen Museums in Wien. 66: 139-204. gs

Knappertsbusch, M. (2000). Morphological evolution of the coccolithophorid Calcidiscus leptoporus from the Early Miocene to recent. Journal of Paleontology. 74(4): 712-730. gs

Lehotayova, R. & Priewalder, H. (1978). Cycloperfolithus, eine neue Nannofossil-Gattung aus dem Badenien der Zentralen Paratethys. In, Papp, A. , Cicha, I. , Senes, J. & et al. (eds) Chronostratigraphie und Neostratotypen -Miozan N, BadenieM-4: IGCP Proj. 25. 486-489. gs

Quinn, P., Sáez, A. G., Baumann, K. -H., Steel, B. A., Sprengel, C. & Medlin, L. K. (2004). Coccolithophorid biodiversity: Evidence from the cosmopolitan species Calcidiscus leptoporus. In, Theirstein, H. R. & Young J. R. (eds) Coccolithophores - From molecular processes to global impact. 299-326. gs

Wilcoxon, J. A. (1970a). Cyclococcolithina Wilcoxon nom. nov. (nom. subst. pro Cyclococcolithus Kamptner, 1954). Tulane Studies in Geology and Paleontology. 8: 82-83. 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


Calcidiscus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 4-4-2020

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