Distinguishing features:
Parent taxon (Rhagodiscus): Loxolith coccoliths with low rim and central-area filled by a granular plate which may be perforate and/or spine-bearing. In xpl the rim is unicyclic moderately bright, the central area is granular, lacking a clear extinction cross.
This taxon: Reniform Rhagodiscus with an irregularly thickened rim.
Taxonomy:
Farinacci & Howe catalog pages: R. reniformis *
Distinguishing features:
Parent taxon (Rhagodiscus): Loxolith coccoliths with low rim and central-area filled by a granular plate which may be perforate and/or spine-bearing. In xpl the rim is unicyclic moderately bright, the central area is granular, lacking a clear extinction cross.
This taxon: Reniform Rhagodiscus with an irregularly thickened rim.
Search data:
LITHS: murolith, asymmetric, CA: plate, CROSS-POLARS: rim-unicyclic, R-prominent, |
Lith size: 7->9µm; Data source notes: illustrated specimens |
Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Lees & Bown 2005 - consistently present to end Cret
First occurrence (base): within Turonian Stage (89.39-93.90Ma, base in Turonian stage). Data source: Burnett 1998
Plot of occurrence data:
Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs O Crux, J. A. (1980). A biostratigraphical study of Upper Cretaceous nannofossils from South-east England and North France. PhD thesis, University College London. -. 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 Lees, J. A. & Bown, P. R. (2005). Upper Cretaceous calcareous nannofossil biostratigraphy, ODP Leg 198 (Shatsky Rise, Northwest Pacific Ocean). Proceedings of the Ocean Drilling Program, Scientific Results. 198: 1-60. gs Perch-Nielsen, K. (1973). Neue Coccolithen aus dem Maastrichtien von Danemark, Madagaskar und Agypten. Bulletin of the Geological Society of Denmark. 22: 306-333. gs Perch-Nielsen, K. (1981). Nouvelles observations sur les nannofossiles calcaires a la limite Crétacé-Tertiaire près de El Kef (Tunisie). Cahiers de Micropaléontologie. 3: 25-37. gs Thibault, N. (2010). Calcareous nannofossils from the boreal Upper Campanian- Maastrichtian chalk of Denmark. Journal of Nannoplankton Research. 31(1): 39-56. gs References:
Rhagodiscus reniformis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 9-10-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=11029 Go to Archive.is to create a permanent copy of this page - citation notes |
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