Nannotax3 - ntax_cenozoic - Chiastozygaceae

Nannotax3 - ntax_cenozoic - Chiastozygaceae Nannotax3 - ntax_cenozoic - Chiastozygaceae

Chiastozygaceae

Classification: ntax_cenozoic -> Mesozoic Survivors -> Chiastozygaceae
Sister taxa: Biscutaceae, Chiastozygaceae, Markalius, Watznaueriaceae

Daughter taxa (time control age-window is: 0-800Ma)		Granddaughter taxa
	Jakubowskia Elliptical murolith with narrow rim and wide vacant central area.	Jakubowskia leoniae Jakubowskia sp.
	Neocrepidolithus Murolith (loxolith) coccoliths with broad, high rim and narrow or closed central-area, which may be spanned by bars.	Neocrepidolithus cohenii Neocrepidolithus cruciatus Neocrepidolithus dirimosus Neocrepidolithus fossus Neocrepidolithus grandiculus Neocrepidolithus neocrassus Neocrepidolithus sp.
	Staurolithites Murolith (loxolith) coccoliths with relatively narrow rim and wide central area spanned by axial cross bars. The cross is usually spine bearing. Inner/proximal rim cycle is variably developed and so the LM image may be unicyclic or bicyclic.	Staurolithites primaevus Staurolithites sp.
	Zeugrhabdotus Murolith (loxolith) coccoliths with central area spanned by variably constructed transverse bar. The bar is usually spine bearing. Inner/proximal rim cycle is variably developed and so the LM image may be unicyclic or bicyclic. Delicate lateral bars may also be present but are generally only seen in exceptional preservation.	Zeugrhabdotus recens Zeugrhabdotus sigmoides Zeugrhabdotus sp.

Taxonomy:

Citation: Chiastozygaceae Rood et al., 1973

taxonomic rank: Family

Distinguishing features:
Parent taxon (Mesozoic Survivors): Mesozoic taxa which occur in low abundances in the early Palaeogene.
This taxon: Loxolith coccoliths with variably-developed proximal/inner-cycles and a central-area spanned by axial, non-axial or diagonal crossbars or a single transverse bar. LM image includes both unicyclic and bicyclic types. Outer rim clockwise-imbricate.

Original description: Diagnosis: Coccoliths with an eiffellithalid rim having a central structure consisting of a cross aligned in the equal axes of the ellipse.

Farinacci & Howe catalog pages: Chiastozygaceae *

Morphology:

Chiastozygaceae throughout the Mesozoic and in the survivor species show clockwise imbrication of the outer rim. In contrast the Zygodiscales are an exclusively Cenozoic group, they show show anti-clockwise imbrication - and also typically have finer elements. So, although both groups form murolith coccoliths, they are morphologically distinct and may be unrealted.

Search data:

Lith size: 4->13.5µm;

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 NP12 zone (100% up, 50.5Ma, in Ypresian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NJ17a subzone (146.27-148.67Ma, base in Tithonian 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 Parent: Mesozoic Survivors

References:

Rood, A. P., Hay, W. W. & Barnard, T. (1973). Electron microscope studies of Lower and Middle Jurassic coccoliths. Eclogae Geologicae Helvetiae. 66: 365-382. gs O

Chiastozygaceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 10-12-2024

Taxon Search:

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=280 Go to Archive.is to create a permanent copy of this page - citation notes

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