Distinguishing features:
Parent taxon (Broinsonia): Outer rim of V-units, with slight clockwise obliquity, visible on distal surface and form dark rim in LM; central-area spanned by an axial cross, grill or perforate plate. 3 tiers visible in side view.
This taxon: axial cross with lateral bars, supporting low spine
Taxonomy:
Farinacci & Howe catalog pages: A. cenomanicus * , A. undatus * , A. vimineus * , B. dempta *
Distinguishing features:
Parent taxon (Broinsonia): Outer rim of V-units, with slight clockwise obliquity, visible on distal surface and form dark rim in LM; central-area spanned by an axial cross, grill or perforate plate. 3 tiers visible in side view.
This taxon: axial cross with lateral bars, supporting low spine
Morphology:
Size:
Tags | LITHS: placolith, elliptical, CA: cross-axial, grill, process, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent, |
Metrics | Lith size: 5->10µm; Data source notes: original descriptions & illustrated specimens |
Geological Range:
Last occurrence (top): in lower part of UC3b subzone (20% up, 95.7Ma, in Cenomanian stage). Data source: Burnett 1998, fig. 6.2
First occurrence (base): within Albian Stage (100.50-112.95Ma, base in Albian stage). Data source: Burnett 1998
Plot of occurrence data:
Black, M. (1973). British Lower Cretaceous Coccoliths. I-Gault Clay (Part 2). Palaeontographical Society Monograph. 127: 49-112. gs 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 Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gs O 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 Lambert, B. (1993). Nannofossiles calcaires de l'Albien supérieur et du Vraconnien du Cameroun méridional (Deuxième Partie). Cahiers de Micropaléontologie. 8(2): 183-225. 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. gsReferences:
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Broinsonia cenomanica compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 13-8-2022
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10119 Go to Archive.is to create a permanent copy of this page - citation notes |
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