Helicosphaeraceae


Ancestry: Coccolithophores -> Zygodiscales -> Helicosphaeraceae
Sister taxa: Helicosphaeraceae, Pontosphaeraceae, Zygodiscaceae,

Short diagnosis: Varimorphic; liths placolith-like but with helical shield structure; arranged in spiral on coccosphere


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Coccoliths with helical flange; arranged spirally on the coccosphere

Taxonomy:

Citation: Helicosphaeraceae Black, 1971
Rank: Family
Notes & discussion: Taxa included: family contains only one genus, Helicosphaera

Farinacci & Howe catalog pages:

Short diagnosis: Varimorphic; liths placolith-like but with helical shield structure; arranged in spiral on coccosphere


Morphology remarks: Coccospheres ellipsoidal with a prominent flagellar opening. Coccoliths arranged spirally round the coccosphere and may vary slightly in size and shape from the antapex to the flagellar pole.
Coccolith structure - Outer rim (V-units) of the coccoliths are modified into a helical flange, ending in a wing or spike. R-units form the baseplate and extend to form blanket of small elements (Young et al. 2004). Central-area bars may be conjunct, disjunct or absent. Theodoridis (1984) discusses the structure.

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): within Ypresian Stage (47.84-55.96Ma, base in Ypresian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Black, M., (1971). The systematics of coccoliths in relation to the paleontological record. In: Funnell, B.M. and Riedel, W.R. (Editors), The Micropaleontology of the Oceans. Cambridge University Press, Cambridge, pp. 611-624.

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.

Theodoridis, S., (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin, 32: 1-271.

Young, J.R.; Henriksen, K. & Probert, I., (2004). Structure and morphogenesis of the coccoliths of the CODENET species. In: Thierstein, H.R. and Young, J.R. (Editors), Coccolithophores - From molecular processes to global impact. Springer, pp. 191-216.


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Helicosphaeraceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-7-2017

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