Distinguishing features:
Parent taxon (Radiolithus): Near circular to stellate eprolithids with relatively narrow wall formed from 9-16 brick-like, wall-cycle elements surrounding a wide central area spanned by an amedian diaphragm. The wall is usually lower than those seen in Eprolithus.
This taxon: Radiolithus with 9 wall-elements and high wall.
Farinacci & Howe catalog pages:
P. orbiculatus *
| LITHS: nannolith-radiate, circular, cylindrical, CA: vacant, closed, CROSS-POLARS: T-prominent, |
| Lith size: 4->8µm; Segments: 9->9; Data source notes: illustrated specimens |
Geological Range:
Last occurrence (top): within Turonian Stage (89.39-93.90Ma, top in Turonian stage). Data source: PRB nannotax entry
First occurrence (base): at base of BC21 zone (0% up, 118.8Ma, in Aptian stage). Data source: PRB nannotax entry
Plot of occurrence data:
Bown, P. R. (2001). Calcareous nannofossils of the Gault, Upper Greensand and Glauconitic Marl (Middle Albian-Lower Cenomanian) from the BGS Selborne boreholes, Hampshire. Proceedings of the Geologists' Association. 112: 223-236. gs Crux, J. A. (1980). A biostratigraphical study of Upper Cretaceous nannofossils from South-east England and North France. PhD thesis, University College London. -. gs Forchheimer, S. (1972). Scanning electron microscope studies of Cretaceous coccoliths from the Köpingsberg Borehole No. 1, SE Sweden. Sveriges Geologiska Undersökning, Series C. #668, 65: 1-141. gs O Gale, A. S., et al. (2011). The uppermost Middle and Upper Albian succession at the Col de Palluel, Hautes-Alpes, France: An integrated study (ammonites, inoceramid bivalves, planktonic foraminifera, nannofossils, geochemistry, stable oxygen and carbon isotopes, cyclostratigraphy). Cretaceous Research. 32: 59-130. gs Kennedy, W. J., et al. (2000). Integrated stratigraphy across the Aptian-Albian boundary in the Marnes Bleues, at the Col de Pre _-Guittard, Arnayon (Drome), and at Tartonne (Alpes-de-Haute-Provence), France: a candidate Global Boundary Stratotype Section and Boundary Point for the base of the Albian Stage. Cretaceous Research. 21: 591-720. gs Püttmann, T. & Mutterlose, J. (2019). Calcareous nannofossils from a Late Cretaceous nearshore setting. Journal of Nannoplankton Research. S4: 81-88. gs Varol, O. (1992). Taxonomic revision of the Polycyclolithaceae and its contribution to Cretaceous biostratigraphy. Newsletters on Stratigraphy. 27(93-127): -. gsReferences:

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Radiolithus orbiculatus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 11-6-2026
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10979 Go to Archive.is to create a permanent copy of this page - citation notes |
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