Nannotax3 - ntax_Farinacci - Zygodiscales Nannotax3 - ntax_Farinacci - Zygodiscales

CATALOG - Zygodiscales


Folder trail: ntax_Farinacci -> Z -> Zygodiscales
Folders this level: Zebrashapka, Zeugrhabdotus, Zygodiscaceae, Zygodiscales, Zygodiscineae, Zygodiscoideae, Zygodiscus, Zygolithaceae, Zygolithites, Zygolithus, Zygosphaera, Zygosphaeraceae, Zygosphaerales, Zygosphaeroideae, Zygostephanos, Zygrhablithaceae, Zygrhablithales, Zygrhablithus

Original descriptions of taxa. For coccolithophores, and many calcispheres, these are pages from the Farinacci & Howe Catalog of Calcareous Nannofossils. In other cases (e.g. non-calcifying haptophytes) the data is directly compiled on this site. The "Catalogue of Calcareous Nannofossils" was originally compiled by Prof A. Farinacci 1969-1989, since 2000 it has been updated and extended by Richard Howe - see The Farinacci and Howe Catalog - an Introduction.
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Current identification/main database link: Zygodiscales Young & Bown, 1997

Compiled data

Citation: Zygodiscales Young & Bown, 1997
Taxonomic rank: order
Described on page(s) : 37
Current citation: Zygodiscales Young & Bown, 1997


Original Description

Muroliths, and modified descendants, with an outer rim-cycle ofV-units showing anticlockwise imbrication and an inner rim-cycle showing clockwise imbrication - the opposite imbrication sense to Eiffellithales. This is a diverse group but with clear evolutionary relationships (e.g. Romein, 1979; Aubry, 1989). Central-area structures include disjunct transverse bars, diagonal crosses and perforate plates but no spines.

Extra details from original publication
Comments: Often assumed to have evolved from the Eiffellithales, via Chiastozygus, Zeugrhabdotus or Placozygus. However, this is not based upon any directly observable transitions and the opposite imbrication directions of the rim-cycles in the two orders makes this questionable. It is equally likely that the first member of the family, Neochiastozygus, evolved from a quite different Cretaceous ancestor.

NB. Regroupings - a conventional subdivision into three families is followed here, however:
  1. The Pontosphaeraceae vs Zygodiscaceae subdivision is not obviously logical. 
  2. The Neococcolithes group arguably should be a separate group from the rest. 
  3. Grouping could be done via a new suborder or by making them all subfamilies of Pontosphaeraceae (this would have to be used since it has priority).

References:

Aubry, M. -P. (1989b). Phylogenetically based calcareous nannofossil taxonomy: implications for the interpretation of geological events. In, Crux, J. A. & van Heck, S. E. (eds) Nannofossils and their applications: Proceedings of the 2nd INA Conference, London 1987. British Micropalaeontological Society Publication Series . 21-40. gs

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

Young, J. R. & Bown, P. R. (1997). Cenozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 36-47. gs


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Zygodiscales: Catalog entry compiled by <% compiler %>. Viewed: 21-5-2026

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