Distinguishing features: Nannoliths formed of multiple layers of thin elements, arranged with rotational symmetry, and showing tangential c-axis orientations.
Daughter taxa (time control age-window is: 0-800Ma)
Granddaughter taxa
Families included by Lees & Bown 2016
Braarudosphaeraceae Nannoliths constructed from 5 (rarely 6) segments which form a pentalith (a five-sided plate); C-axes tangential to pentalith outline in plan view; individual crystal units show laminar ultrastructure.
Nannoconaceae Conical, globular or cylindrical nannoliths composed of plates spirally-arranged around an axial cavity or canal. Plate c-axes are arranged tangentially to the longitudinal axis.
Polycyclolithaceae Nannoliths composed of two superposed wall cycles and a central-area which may be closed, open and vacant, or spanned by a diaphragm-like structure. Elements have tangential c-axis orientation.
Citation: Braarudosphaerales Aubry 2013 emend Lees & Bown 2016Rank: OrderTaxonomic discussion: Lees & Bown (2016) emended the order Braarudosphaerales to include the Nannoconaceae on the grounds that pentaliths and nannoconids both showed structures formed of multiple layers of thin elements. In the case of pentaliths these thin elements appear as laminae witin individual crystal units, in nannoconids they are stacked with offset, both groups appear at the end Jurassic and show tangential c-axis orientations as well as simple rotational symmetry, (without modification by central area structures or elongation into elliptical forms). Varol & Bowman (2019) have since shown that Polycyclolithus is a nannoconid, from side view observations with a mobile mount. Other possibly related taxa which show tangential c-axes and simple rotational symettry but not stacked layers of elements include the Polycyclolithaceae and the genera Kokia, and Tegulalithus. These are now tentively included here.
Distinguishing features: Nannoliths formed of multiple layers of thin elements, arranged with rotational symmetry, and showing tangential c-axis orientations.
Morphology: To determine if c-axes are tangential (as in this group) as opposed to radial (as in the R-units that form the bright part of most heterococccoliths) nannofossils should be observed in cross-polarised light with a gypsum (1λ) plate or other accesory plate (see e.g. Moshkovitz & Osmond 1989).
Search data:
Tags
LITHS: nannolith-radiate, pentagonal,
Metrics
Lith size: 0->0µm; Segments: 5->5;
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range: Last occurrence (top): Extant Data source: Total of range of species in this database First occurrence (base): near top of Oxfordian Stage (89% up, 157.9Ma, in Oxfordian stage). Data source: Total of range of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page Parent: ntax_mesozoic
References:
Aubry, M. -P. (2013). Cenozoic Coccolithophores: Braarudosphaerales. Micropaleontology Press, American Museum of Natural History, New York. 1-336. gs
Lees, J. A. & Bown, P. R. (2016). New and intriguing calcareous nannofossils from the Turonian (Upper Cretaceous) of Tanzania. Journal of Nannoplankton Research. 36(1): 83-95. gsVO
Moshkovitz, S. & Osmond, K. (1989). The optical properties and microcrystallography of Arkhangelskiellaceae and some other calcareous nannofossils of the Late Cretaceous. In, Crux, J. A. & van Heck, S. E. (eds) Nannofossils and their applications: Proceedings of the 2nd INA Conference, London 1987. British Micropalaeontological Society Publication Series. 76-97. gs
Varol, O. & Bowman, A. R. (2019). Taxonomic revision of selected Late Jurassic (Tithonian) calcareous nannofossils and the application of mobile mounting. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 291: 65-87. gs
Braarudosphaerales compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-7-2021
