Nannotax3 - ntax_cenozoic - Zygodiscaceae Nannotax3 - ntax_cenozoic - Zygodiscaceae


Classification: ntax_cenozoic -> Zygodiscales -> Zygodiscaceae
Sister taxa: Helicosphaeraceae, Pontosphaeraceae, Zygodiscaceae

Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
R-units well-developed
Modified muroliths with high walls (higher at one end and forming an asymmetric flange) and wide central area usually spanned by a disjunct, complex tranverse bar.
Lophodolithus acutus
Lophodolithus luntii
Lophodolithus mochlophorus
Lophodolithus mytiliformis
Lophodolithus nascens
Lophodolithus reniformis
Lophodolithus rotundus
Lophodolithus sp.

Muroliths with well-developed V- and R-units and diagonal or asymmetric cross in central-area.

Muroliths with well-developed V- and R-units and transverse bar in central-area. LM image is dominated by bright, broad R-unit inner cycle; V-unit cycle is narrow.
Zygodiscus adamas
Zygodiscus cearae
Zygodiscus clausus
Zygodiscus herlyni
Zygodiscus multiforus
Zygodiscus plectopons
Zygodiscus sheldoniae
Zygodiscus sp.

R-units vestigial, central structures septa extending through the coccolith
Muroliths with very high wall (similar to coccolith width) and well-developed central-area cross. V-unit cycle dominates and results in a moderately birefringent unicyclic LM image.
Chiphragmalithus acanthodes
Chiphragmalithus armatus
Chiphragmalithus barbatus
Chiphragmalithus calathus
Chiphragmalithus muzylevii
Chiphragmalithus vandenberghei
Chiphragmalithus sp.

Narrowly elliptical to oblong (or parallelogram-like), relatively high muroliths with one or two transverse bars. R-unit relict or absent and so LM image is unicyclic.
Isthmolithus recurvus
Isthmolithus rhenanus
Isthmolithus unipons
Isthmolithus sp.

Muroliths with diagonal to H-shaped cross bars. R-unit relict or absent and so LM image is unicyclic.
Neococcolithes dubius
Neococcolithes lososnensis
Neococcolithes minutus
Neococcolithes nudus
Neococcolithes protenus
Neococcolithes purus
Neococcolithes radiatus
Neococcolithes sp.

Typically large (>8 µm) cruciform nannoliths with high curving ridges running from the centre to ray tips.
Nannotetrina spinosa
Nannotetrina pappii
Nannotetrina fulgens
Nannotetrina alata
Nannotetrina cristata
Nannotetrina plana
Nannotetrina ruda
Nannotetrina sp.


Citation: Zygodiscaceae Hay&Mohler, 1967 
taxonomic rank: Family

Distinguishing features:
Parent taxon (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

This taxon: Muroliths with rim formed from well-developed V- and variably developed R-units, with opposite imbrication directions, and central area structures that include disjunct transverse bars and diagonal crosses. R-units vestigial or not observed in several genera (Chiphragmalithus, Isthmolithus, Neococcolithes).

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


Muroliths with rim formed from well-developed V- and variably developed R-units, with opposite imbrication directions, and central area structures that include disjunct transverse bars (Zygodiscus, Lophodolithus) and diagonal crosses (Neochiastozygus, Neococcolithes, Chiphragmalithus).
R-units are vestigial or absent in several genera (Chiphragmalithus, Isthmolithus, Neococcolithes, Nannotetrina) and in these genera the central structures are formed of vertical septa that extend from the proximal surface to the distal surface and often protrude above the wall. The nannolith Nannotetrina was long suspected to be related to this group (Bramlette & Sulivan 1961, Perch-Nielsen 1985), by further reduction of the rim and expansion of the central structure, and this was demonstrated by Bown & Newsam (2017) through lineage study in well-preserved material from IODP expedition 342.

Coccoliths vary in size from small to very large, mostly medium to large size and including some taxa producing very big coccoliths (e.g. Nannotetrina, Lophodolithus).  

Search data:
Lith size: 3->30µm;
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 Oligocene Epoch (100% up, 23Ma, in Aquitanian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NP1 zone (65.47-66.04Ma, base in Danian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:


Aubry, M. -P. (1990). Handbook of Cenozoic calcareous nannoplankton. Book 4: Heliolithae (Helicoliths, Cribriliths, Lopadoliths and others). Micropaleontology Press, American Museum of Natural History, New York. 1-381. gs

Bown, P. R. & Newsam, C. (2017). Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411). Journal of Nannoplankton Research. 37(1): 25-60. gs O

Bramlette, M. N. & Sullivan, F. R. (1961). Coccolithophorids and related nannoplankton of the Early Tertiary in California. Micropaleontology. 7(2): 129-188. gs

Hay, W. W. & Mohler, H. P. (1967). Calcareous nannoplankton from Early Tertiary rocks at Point Labau, France and Paleocene-Early Eocene correlations. Journal of Paleontology. 41(6): 1505-1541. gs

Perch-Nielsen, K. (1985). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs

Romein, A. J. T. (1979). Lineages in Early Paleogene calcareous nannoplankton. Utrecht Micropaleontological Bulletin. 22: 1-231. gs O


Zygodiscaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-5-2024

Taxon Search:
Advanced Search

Short stable page link: Go to to create a permanent copy of this page - citation notes

Nannotax is being sponsored through 2024 by Woodside Energy and Shell USA

Add Comment

* Required information
Captcha Image
Powered by Commentics


No comments yet. Be the first!