Gephyrocapsa omega


Classification: ntax_cenozoic -> Isochrysidales -> Noelaerhabdaceae -> Gephyrocapsa -> Gephyrocapsa omega
Sister taxa: G. oceanica, G. muellerae, G. ornata, G. ericsonii, G. sp elevated bridge ⟩⟨ G. caribbeanica, G. omega, G. lumina, G. small, G. sp.

Taxonomy:

Citation: Gephyrocapsa omega Bukry 1973
Rank: Species
Synonyms: NB G. omega was decribed by Bukry (1973) in DSDP Initial Reports vol 16 published in April 1973 whereas G. parallela was described by Hay & Beaudry (1973) in DSDP Initial Reports vol 15 published in December 1973. Since G. omega was published first it has priority.
Variants:
Varol (2004) described three subspecies from the same sediment sample. In conventional taxonomy all three would be included within G. omega.
Taxonomic discussion: Samtleben (1980), Rio (1982) and Matsuoka & Okada (1990) have all reported that after the small Gephyrocapsa event there is a population of largish Gephyrocapsa with very high bridge angles (i.e bridges nearly parallel to short axis) - although each used a different name for them (see synonymy above). 
Of the formally proposed names G. omega Bukry (1973) has priority and seems to be increasingly widely used. [Samtleben (1980), however, argued that this name was inappropriate since the morphotype was best regarded as a chrono-subspecies of G. oceanica and since the holotype of G. omega was from above the typical range of the form.]

Distinguishing features: Intermediate to large size species of Gephyrocapsa; bridge at low angle to short axis, central area broad.

Farinacci & Howe catalog pages: G. omega * , G. parallela * , G. caribbeanica clausa * , G. oceanica grandis * , G. omega gigas * , G. oceanica rodela *


Morphology: Similar to modern G. oceanica but mean bridge angle higher and lower maximum size. Often included within G. oceanica.

Size: Typically 4-4.6µm long; bridge angle 65-75° (Samtleben 1980)

Search data:
TagsLITHS: placolith, elliptical, CA: ca_conjunct, grill, bar,
CSPH: equant, monomorphic, CROSS-POLARS: rim-unicyclic, R-prominent,
MetricsLith size: 4->5µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Dominates assemblages in the Mid Pleistocene, after the small Gephyrocapsa interval. Its' FO is widely used in high resolution Quaternary biostratigraphy. Raffi et el (2006) record the FO as occuring variably between MIS26 and 28 (0.96 to 1.4Ma).
Last occurrence (top): within MIS-15 Isotope stage (0.57-0.65Ma, top in Ionian stage). Data source: Maiorano & Marino 2004
First occurrence (base): within MIS-29 Isotope stage (1.02-1.05Ma, base in Calabrian stage). Data source: Raffi et al. 2006

Plot of occurrence data:

References:

Bukry, D. (1973c). Coccolith stratigraphy, eastern equatorial Pacific, Leg 16, Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project. 16: 653-711. gs V O

Hay, W. W. & Beaudry, F. M. (1973). Calcareous nannofossils - Leg 15. Initial Reports of the Deep Sea Drilling Project. 15: 625-684. gs V O

Maiorano, P. & Marino, M. (2004). Calcareous nannofossil bioevents and environmental control on temporal and spatial patterns at the early–middle Pleistocene. Marine Micropaleontology. 53: 405-422. gs

Matsuoka, H. & Okada, H. (1989). Quantitative analysis of Quaternary nannoplankton in the subtropical Northwestern Pacific Ocean. Marine Micropaleontology. 14: 97-118. gs

Matsuoka, H. & Okada, H. (1990). Time-progressive morphometric changes of the genus Gephyrocapsa in the Quaternary sequence of the tropical Indian Ocean, Site 709. Proceedings of the Ocean Drilling Program, Scientific Results. 115: 255-270. gs V O

Raffi, I. et al. (2006). A review of calcareous nannofossil astrobiochronology encompassing the past 25 million years. Quaternary Science Reviews. 25: 3113-3137. gs

Rio, D. (1982). The fossil distribution of coccolithophore genus Gephyrocapsa Kamptner and related Plio-Pleistocene chronostratigraphic problems. Initial Reports of the Deep Sea Drilling Project. 68: 325-343. gs V O

Samtleben, C. (1980). Die Evolution der Coccolithophoriden-Gattung Gephyrocapsa nach Befunden im Atlantik. Paläontologische Zeitschrift. 54: 91-127. gs

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gs V O


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Gephyrocapsa omega compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 12-4-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=614 Go to Archive.is to create a permanent copy of this page - citation notes



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