Nannolith families inc sed


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

Short diagnosis: Haptophytes forming calcareous structures not obviously homologous with heterococcoliths, holococcoliths, or discoasteralids


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Horseshoe-shaped rod-shaped nannoliths and simple hoop-coccoliths formed in one phase of life cycle, planolith heterococcoliths in the other.

Hemispherical to cylindrical nannoliths, with walls constructed from one to several cycles of thin elements, enclosing a hollow central space; the nannolith tapers distally, and may have long apical spines or processes.

Large (10-20µm) triangular to stellate nannoliths with porous structure formed from small crystallites. In xpl behave as single crystal unit with low birefringence

Three apparently unique genera, not-included in described families

Nannoliths with rhombic and tri-radiate morphologies, and non-birefringent images in XPL. Incorporating the genera Rhomboaster and Tribrachiatus.

Taxonomy:

Citation: Nannolith familes incertae sedis - informal
Rank: informal grouping

Farinacci & Howe catalog pages:

Short diagnosis: Haptophytes forming calcareous structures not obviously homologous with heterococcoliths, holococcoliths, or discoasteralids


Morphology remarks: These groups of nannofossils are thought to be related to coccolithophores, but produce structures which are neither heterococcoliths nor holococcoliths.
The term nannolith has been used, especially by palaeontologists, as a convenient term for structures about the same size as coccoliths and occurring with coccoliths, but lacking definite coccolith affinities. In the modern nannoflora, there are fewer groups of cryptic origins, and the term has been less widely used. However, it is useful for calcareous structures that are thought to be formed by haptophytes, but probably by a different biomineralisation process to either heterococcoliths or holococcoliths (Young et al. 1999).
NB The first use of the term in this sense appears to have been by Haq (1978, in Introduction to Marine Micropaleontology), and this was followed by Perch-Nielsen (1985, in Plankton Stratigraphy). By contrast, Aubry (1988 et seq., Handbook of Calcareous Nannofossils) places most of these groups in the Ortholithae.

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): within Aptian Stage (112.95-126.30Ma, base in Aptian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Aubry, M.-P., (1988). Handbook of Cenozoic calcareous nannoplankton. Book 2: Ortholithae (Catinasters, Ceratholiths, Rhabdoliths). Micropaleontology Press, American Museum of Natural History, New York, 279 pp.

Haq, B.U., (1978). Calcareous nannoplankton. In: Haq, B.U. and Boersma, A. (Editors), Introduction to marine micropaleontology. Elsevier, Amsterdam, pp. 79-108.

Perch-Nielsen, K., (1985). Cenozoic calcareous nannofossils. In: Bolli, H.M., Saunders, J.B. and Perch-Nielsen, K. (Editors), Plankton Stratigraphy. Cambridge University Press, Cambridge, pp. 427-555.

Perch-Nielsen, K., (1985). Mesozoic calcareous nannofossils. In: Bolli, H.M., Saunders, J.B. and Perch-Nielsen, K. (Editors), Plankton Stratigraphy. Cambridge University Press, Cambridge, pp. 329-426.

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 - Nannolith families inc sed by: Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 25-6-2017

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