Nannotax3 - ntax_mesozoic - Chiastozygus platyrhethus <title>Nannotax3 - ntax_mesozoic - Chiastozygus platyrhethus

Chiastozygus platyrhethus


Classification: ntax_mesozoic -> Eiffellithales -> Chiastozygaceae -> Chiastozygus -> Chiastozygus platyrhethus
Sister taxa: C. amphipons, C. bifarius, C. lamprostauros, C. litterarius, C. platyrhethus, C. spissus ⟩⟨ C. antiquus, C. garrisonii, C. stylesii, C. trabalis ⟩⟨ C. propagulis, C. quadriperforatus, C. synquadriperforatus, C. tenuis, C. sp.

Distinguishing features:
Parent taxon (Chiastozygus): Murolith (loxolith) coccoliths with relatively narrow rim and wide central area spanned by diagonal bars. Inner/proximal rim cycle is variably developed and so the LM image may be unicyclic or bicyclic.
This taxon: Rim dark unicyclic, narrow; Cross bright with a distinct median extinction line in XPL; Central area wide


Taxonomy:

Citation: Chiastozygus platyrhethus Hill, 1976
Rank: Species

Farinacci & Howe catalog pages: C. platyrhethum *

Distinguishing features:
Parent taxon (Chiastozygus): Murolith (loxolith) coccoliths with relatively narrow rim and wide central area spanned by diagonal bars. Inner/proximal rim cycle is variably developed and so the LM image may be unicyclic or bicyclic.
This taxon: Rim dark unicyclic, narrow; Cross bright with a distinct median extinction line in XPL; Central area wide


Morphology:

Similar to C. bifarius but rim narrower and cross brighter. Probably many authors use only one of the two taxa.

Size:


Ecology & Biogeography


Biology & life-cycles

Phylogenetic relations

Search data:
LITHS: murolith, elliptical, CA: ca_disjunct, process, diagonal cross, CROSS-POLARS: rim-unicyclic, V-prominent,
Lith size: 6->10µm;
Data source notes: original description & illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Coniacian Stage (86.26-89.77Ma, top in Coniacian stage). Data source: Bown et al. 1998
First occurrence (base): within Aptian Stage (112.95-126.30Ma, base in Aptian stage). Data source: Bown et al. 1998

Plot of occurrence data:

References:

Applegate, J. L. & Bergen, J. A. (1988). Cretaceous calcareous nannofossil biostratigraphy of sediments recovered from the Galicia Margin, ODP Leg 103. Proceedings of the Ocean Drilling Program, Scientific Results. 103: 293-348. gs O

Bown, P. R. (2005c). Early to Mid-Cretaceous Calcareous Nannoplankton from the Northwest Pacific Ocean, Leg 198, Shatsky Rise. Proceedings of the Ocean Drilling Program, Scientific Results. 198: 1-82. gs O

Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Lower Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 86-131. gs O

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs O

Hill, M. E. (1976). Lower Cretaceous calcareous nannofossils from Texas and Oklahoma. Palaeontographica Abteilung B Palaeophytologie. 156: 103-179. gs

Kanungo, S., Bown, P. R. & Gale, A. S. (2020). Cretaceous (Albian-Turonian) calcareous nannofossil biostratigraphy of the onshore Cauvery Basin, southeastern India. Cretaceous Research. 118 [2021]: 1-22. gs

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Chiastozygus platyrhethus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 30-1-2023

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