Distinguishing features: Parent taxon (Braarudosphaerales): Nannoliths formed of multiple layers of thin elements, arranged with rotational symmetry, and showing tangential c-axis orientations. This taxon: 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.
Daughter taxa (time control age-window is: 0-800Ma)
Granddaughter taxa
Braarudosphaera Pentaliths with trapezoidal segments and sutures that go to edges of the pentagon.
Distinguishing features: Parent taxon (Braarudosphaerales): Nannoliths formed of multiple layers of thin elements, arranged with rotational symmetry, and showing tangential c-axis orientations. This taxon: 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.
Morphology: Fossil lith types show considerable diversty, including very tall and heavily calcified forms and forms with stellate outlines. The extant Braarudosphaera bigelowii has a cell-wall covering of twelve pentaliths, which form an imperforate dodecahedron. Two main morphotypes are seen through much of the evolutionary history: Braarudosphaera in which the sutures between segments go to edges of the pentagon and Micrantholithus in which the sutures go to the points of the pentagon. The two styles may form distinct taxa but in some cases single liths may change from the Braarudosphaera- to Micrantholithus- style up (or down) through the laminations (e.g., Lambert, 1986).
Search data:
LITHS: nannolith-radiate, pentagonal, CA: closed,
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 ranges of the species in this database First occurrence (base): within Berriasian Stage (137.70-143.10Ma, base in Berriasian stage). Data source: Total of ranges 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: Braarudosphaerales
References:
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. gsO
Deflandre, G. (1947a). Braarudosphaera nov. gen., type d'une famille nouvelle de Coccolithophorides actuels a elements composites. Comptes rendus hebdomaire de l'Académie des sciences, Paris. 225: 439-441. gs
Lambert, B. (1986). La notion d'espèce chez le genre Braarudosphaera Deflandre, 1947: mythe et réalité. Revue de Micropaléontologie. 28(4): 255-264. gs
Braarudosphaeraceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 11-10-2024
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