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: Small Rhagodiscus with a birefringent spine/spine base that almost fills the central area.
Taxonomy:
Farinacci & Howe catalog pages: R. dekaenelii *
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: Small Rhagodiscus with a birefringent spine/spine base that almost fills the central area.
Morphology:
LITHS: murolith, elliptical, CA: plate, process, CROSS-POLARS: rim-unicyclic, R-prominent, |
Lith size: 4->6µm; Data source notes: original description |
Geological Range:
Last occurrence (top): within Early Hauterivian Substage (130.60-132.60Ma, top in Hauterivian stage). Data source: Bown et al. 1998
First occurrence (base): within Early Valanginian Substage (135.70-137.70Ma, base in Valanginian stage). Data source: Bown et al. 1998
Plot of occurrence data:
Aguado, R. et al. (2018). A new record of the Weissert episode from the Valanginian succession of Cehegín (Subbetic, SE Spain): bio- and carbon isotope stratigraphy. Cretaceous Research. 92: 122-137. gs Bergen, J. A. (1994). Berriasian to early Aptian calcareous nannofossils from the Vocontian Trough (SE France) and Deep Sea Drilling Site 534: new nannofossil taxa and a summary of low-latitude biostratigraphic events. Journal of Nannoplankton Research. 16(2): 59-69. gs 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 OReferences:
Rhagodiscus dekaenelii compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 11-10-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=11019 Go to Archive.is to create a permanent copy of this page - citation notes |
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