| Daughter taxa: (blue => in age window 0-800Ma) | Granddaughter taxa | ||||
| | | | Coccoliths with helical flange; arranged spirally on the coccosphere | |
Taxonomy:
Distinguishing features: Varimorphic; liths placolith-like but with helical shield structure; arranged in spiral on coccosphere
Farinacci & Howe catalog pages: Helicosphaeraceae [no catalog entry yet]
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.
| Tags | wing, ellipsoidal-----, varimorphic, V-UNITS: distal shield, R-UNITS: blanket, c-str, px-plate, DETAILS: isogyres kinked, isogyres oblique, isogyres separated, |
| Metrics | Lith size: 4->22µm; Sources: |
Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): in lower part of Ypresian Stage (28% up, 53.7Ma, in Ypresian stage). Data source: Total of range of species in this database
Plot of occurrence data:
Black, M. (1971c). The systematics of coccoliths in relation to the paleontological record. In, Funnell, B. M. & Riedel, W. R. (eds) The Micropaleontology of the Oceans. Cambridge University Press, Cambridge 611-624. gs Perch-Nielsen, K. (1985a). Cenozoic calcareous nannofossils. In, Bolli, H. M. , Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gs V O Young, J. R., Henriksen, K. & Probert, I. (2004b). Structure and morphogenesis of the coccoliths of the CODENET species. In, Thierstein, H. R. & Young, J. R. (eds) Coccolithophores - From molecular processes to global impact. Springer, Berlin 191-216. gs V OReferences:
 |
Helicosphaeraceae compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 27-9-2020
Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=696 Go to Archive.is to create a permanent copy of this page - citation notes |