Nannotax3 - ntax_main - Rhagodiscus achlyostaurion

Citation: Rhagodiscus achlyostaurion (Hill 1976) Doeven 1983

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 (4-6µm) Rhagodiscus with relatively narrow central area spanned by a granular plate bearing large spine/spine base. The rim image is distinctly dark in XPL.

Abut 4-6 µm - Hill (1976) described the species as <5µm long but published images include specimens up to at least 6 µm, and this seems to be a discrete species rathe than an artifcial size defined grouping. [my interpretation - JRY 2020]

Geological Range:
Notes: Bown et al. 1998 (fig 5.2) record the base of "R. achylostaurion" near the top of CC6 but the base of true R. achlyostaurion at the base of NC7B/within CC7B
Last occurrence (top): within Coniacian Stage (85.70-89.39Ma, top in Coniacian stage). Data source: Bown et al. 1998
First occurrence (base): in upper part of CC6 zone (80% up, 122.3Ma, in Barremian stage). Data source: Bown et al. 1998 (fig 5.2)

References:

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

Crux, J. A. (1980). A biostratigraphical study of Upper Cretaceous nannofossils from South-east England and North France. PhD thesis, University College London. -. gs

De Kaenel, E., Mojon, P. -O. & Pictet, A. (2020). New biostratigraphical data (calcareous nannofossils, ammonites) and Early to Late Barremian transition in the Urgonien Jaune facies and Marnes de la Russille complex of the Swiss Jura Mountains. Swiss Journal of Palaeontology. 139(6): 1-43. gs O

Doeven, P. H. (1983). Cretaceous nannofossil stratigraphy and paleoecology of the Canadian Atlantic Margin. Bulletin of the Geological Survey of Canada. 356: 1-70. gs

Gale, A. S., Kennedy, W. J., Burnett, J. A., Caron, M. & Kidd, B. E. (1996). The Late Albian to Early Cenomanian succession at Mont Risou, near Rosans (Drôme, SE France): an integrated study (ammonites, inoceramids, planktonic foraminifera, nannofossils, oxygen and carbon isotopes). Cretaceous Research. 17: 515-606. gs

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

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

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

Püttmann, T., Mutterlose, J., Kaplan, U. & Scheer, U. (2019). Reworking of Cenomanian ammonites decoded by calcareous nannofossils (southern Münsterland Basin, northwest Germany). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 291(1): 1-17. gs

Schueth, J. D. & Johnson, K. (2023). Integrated statistical analysis of calcareous nannofossil and elemental geochemistry of an outcrop from of the eastern Cenomanian Western Interior Seaway: Novel insights of shallow marine paleoceanography and nannoplankton paleoecology. Marine Micropaleontology. 184(102290): 1-13. gs

Thomsen, E. (1987). Lower Cretaceous calcareous nannofossil biostratigraphy in the Danish Central Trough. Danmarks Geologiske Undersøgelse. 20: 1-89. gs

Rhagodiscus achlyostaurion

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