Braarudosphaerales


Ancestry: Coccolithophores -> Braarudosphaerales
Sister taxa: Isochrysidales, Coccolithales, Zygodiscales, Syracosphaerales, Coccolith families inc sed, Mesozoic Survivors, Holococcoliths, Braarudosphaerales, Discoasterales, Nannolith families inc sed, hidden,

Short diagnosis: Diploid (?) life-cycle stage covered by pentaliths (plates formed of 5 segments with lamellar sub-structure) formed extracellualrly


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Coccospheres pentagonal dodecahedra formed of five pentagonal plates

Taxonomy:

Citation: Braarudosphaerales Aubry 2013
Rank: Order
Notes & discussion: Recent research has demonstrated that modern Braarudosphaera produces the pentaliths extra-cellularly and that they have a very different structure to heterococcoliths, characterised by laminar sub-structure and tagential c-axis orientations (Hagino et al. 2016). So, they are clearly produced by a different biominerlaisation mode (sensu Young et al. 1999) to either holococcoliths or heterococcoliths. In parallel, molecular genetic data shows they are haptophytes closely related to coccolithophores but either occupying a basal position within the coccolithophore clade or falling just outside it (Takano et al. 2006, Hagino et al. 2013). These two lines of evidence strongly justify separating the group as a discrete order within the haptophyta.
In the Cenozoic the order only contains the one, well-established, family the Braarudosphaeraceae. However, in the Mesozoic there are other groups showing affinities to them - in particular the Nannoconids (Lees & Bown 2016).

Farinacci & Howe catalog pages:

Short diagnosis: Diploid (?) life-cycle stage covered by pentaliths (plates formed of 5 segments with lamellar sub-structure) formed extracellualrly

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): within Cenomanian Stage (93.90-100.50Ma, base in Cenomanian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Aubry, M.-P., (2013). Cenozoic Coccolithophores: Braarudosphae­rales. Atlas of Micropaleontology Series. Micropaleontology Press, New Yourk, 336 pp.

Hagino, K.; Onuma, R.; Kawachi, M. & Horiguchi, T., (2013). Discovery of an Endosymbiotic Nitrogen-Fixing Cyanobacterium UCYN-A in Braarudosphaera bigelowii (Prymnesiophyceae). PLoS ONE, 8(12): 1-11.

Hagino, K.; Tomioka, N.; Young, J.R.; Takano, Y.; Onuma, R. & Horiguchi, T., (2016). Extracellular calcification of Braarudosphaera bigelowii deduced from electron microscopic observations of cell surface structure and elemental composition of pentaliths. Marine Micropaleontology, 125(1): 85-94.

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.

Takano, Y.; Hagino, K.; Tanaka, Y.; Horiguchi, T. & Okada, H., (2006). Phylogenetic affinities of an enigmatic nannoplankton, Braarudosphaera bigelowii based on the SSU rDNA sequences. Marine Micropaleontology, 60: 145-156.

Young, J.R.; Davis, S.A.; Bown, P.R. & Mann, S., (1999). Coccolith ultrastructure and biomineralisation. Journal of Structural Biology, 126: 195-215.


Nannotax3 - Coccolithophores - Braarudosphaerales by: Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 26-6-2017

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