Cyclagelosphaera argoensis


Classification: Mesozoic -> Watznaueriales -> Watznaueriaceae -> Cyclagelosphaera -> Cyclagelosphaera argoensis
Sister taxa: C. margerelii, C. alta, C. reinhardtii, C. rotaclypeata, C. shenleyensis, C. argoensis, C. brezae, C. centrumelliptica, C. deflandrei, C. jiangii, C. lacuna, C. wiedmannii, C. sp.,

Distinguishing features: A large, concavo-convex species of Cyclagelosphaera (6-11 µm) having a broad, distal shield inner cycle and a small central perforation.


Taxonomy:

Citation: Cyclagelosphaera argoensis Bown, 1992
Rank: Species

Farinacci & Howe catalog pages: Cyclagelosphaera argoensis *

Distinguishing features: A large, concavo-convex species of Cyclagelosphaera (6-11 µm) having a broad, distal shield inner cycle and a small central perforation.


Morphology remarks: C. argoensis is distinguished from other species of Cyclagelosphaera by its large size; convexity; and broad, blocky, distal inner cycle. The structure of the distal inner cycle is distinctive when observed in light microscope and distinguishes this species from other large forms, such as Cyclagelosphaera deflandrei.

Geological Range:
Last occurrence (top): within Hauterivian Stage (130.77-133.88Ma, top in Hauterivian stage). Data source: [PRB rough estimate]
First occurrence (base): in mid part of NJT16a subzone (50% up, 148.1Ma, in Tithonian stage). Data source: Casellato 2010, fig16 - secondary marker

Plot of occurrence data:

  • (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Cyclagelosphaera

    References:

    Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 34-85. gs

    Bown, P. R. (1992). New calcareous nannofossil taxa from the Jurassic/Cretaceous boundary interval of Sites 765 and 261, Argo Abyssal Plain. Proceedings of the Ocean Drilling Program. Scientific Results. 123: 369-379. gs

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

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

    Casellato, C. E. (2010). Calcareous nannofossil biostratigraphy of Upper Callovian - Lower Berriasian successions from the Souhern Alps, North Italy. Rivista Italiana di Paleontologia e Stratigrafia. 116(3): 357-404. gs


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    Cyclagelosphaera argoensis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-9-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10339 Go to Archive.is to create a permanent copy of this page - citation notes



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