|Daughter taxa: (blue => in age window 0-800Ma)||Granddaughter taxa|
Distinguishing features: 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.
Farinacci & Howe catalog pages: Chiastozygaceae [no catalog entry yet]
Morphology remarks: 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.
|Metrics||Lith size: 4->13.5µm; |
Last occurrence (top): in upper part of Ypresian Stage (67% up, 50.5Ma, in Ypresian stage). Data source: Total of range of species in this database
First occurrence (base): near base of Tithonian Stage (8% up, 151.5Ma, in Tithonian stage). Data source: Total of range of species in this database
Plot of occurrence data:
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