Taxonomy:
Affinities: Braarudosphaera was long considered a group of highly uncertain affinities and possibly dinoflagellates, but recent molecular genetic data (Takano et al. 2006) has shown that they occupy a basal position within the coccolithophore clade, and so are definitely haptophytes and probably derived in some way from coccolithophores.
Distinguishing features:
Parent taxon (Braarudosphaerales): 2N(?) cell covered by pentaliths (plates formed of 5 segments with lamellar sub-structure) formed extracellularly N: cell motile, covered by scales
This taxon: Coccospheres pentagonal dodecahedra formed of five pentagonal plates
Farinacci & Howe catalog pages: Braarudosphaeraceae + *
Morphology:
Pentalith morphology: Pentaliths consist of five segments, each of which behaves as a discrete crystal-unit with c-axis parallel to edge of the pentalith. A lamellar substructure to the segments is consistently present.
Ecology & Biogeography
Lith size: 2->30µm; Segments: 5->5; |
Geological Range:
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within Cenomanian Stage (93.90-100.50Ma, base in Cenomanian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Aubry, M. -P. (1989a). Handbook of Cenozoic calcareous nannoplankton. Book 3: Ortholithae (Pentaliths, and others), Heliotithae (Fasciculiths, Sphenoliths and others). Micropaleontology Press, American Museum of Natural History, New York. 1-279. gs Bown, P. R. (2005d). Palaeogene calcareous nannofossils from the Kilwa and Lindi areas of coastal Tanzania (Tanzania Drilling Project 2003-4). Journal of Nannoplankton Research. 27(1): 21-95. 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 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 Kelly, D. C., Norris, R. D. & Zachos, J. C. (2003). Deciphering the paleoceanographic signi¢cance of Early Oligocene Braarudosphaera chalks in the South Atlantic. Marine Micropaleontology. 49: 49-63. gs Lefort, F. (1972). Quelques caracteres morphologiques de deux especes actuelles de Braarudosphaera (Chrysophycees, Coccolithophoracees). Botaniste. 20(3): 13-. gs Liebrand, D. et al. (2018). Orbitally forced hyperstratification of the Oligocene South Atlantic Ocean. Paleoceanography and Paleoclimatology. 33: 511-529. gs Peleo-Alampay, A. M., Mead, G. A. & Wei, W. (1999). Unusual Oligocene Braarudosphaera-rich layers of the South Atlantic and their palaeoceanograpghic implications. Journal of Nannoplankton Research. 21(1): 17-26. gs Perch-Nielsen, K. (1985). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge (1): 427-555. gs Perch-Nielsen, K. (1985). Mesozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge (1): 329-426. gs 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. gsReferences:
Braarudosphaeraceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 8-11-2024
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