R. pseudoumbilicus group


Classification: Coccolithophores -> Isochrysidales -> Noelaerhabdaceae -> Reticulofenestra -> R. pseudoumbilicus group
Sister taxa: C. floridanus group, R. bisecta group, R. lockeri group, R. parvula group, R. pseudoumbilicus group, R. reticulata group, R. umbilicus group, R. sp.,

Daughter taxa: (blue => in age window 0-800Ma)
Species of Reticulofenestra with the tube extended as a flaring cup-shaped structure.
Medium to large size reticulofenestrid with central opening
Coccoliths small (3-5µm), intergrades with R. pseudoumbilicus.
Coccoliths very small, <3µm. Probably includes several different species.
Coccoliths small 3-5µm, without slits, intergrades with Pseudoemiliania lacunosa.
Coccoliths >6.5µm, sub-circular or broadly elliptical, intergrades with P. lacunosa.
(sub)circular species
Coccoliths (sub)circular, broad central area (25-50% of coccolith width); NN3-4
Coccoliths circular, with wide central-area, 5-7µm; NN11
Small (3-5µm), (sub)circular, with large central opening (ca 50% of coccolith width)

Taxonomy:

Citation: R. pseudoumbilicus group
Rank: species group

Distinguishing features: Neogene elliptical reticulofenestrids with an open central area (spanned by delicate proximal net, not visible in lm)

Farinacci & Howe catalog pages:

Search data:
TagsLITHS: placolith, elliptical, CA: grill, vacant,
CSPH: spherical, monomorphic, V-UNITS: none, R-UNITS: all, c-str, distal shield, prox shield, tube, DETAILS: ca_conjunct, isogyres kinked, isogyres oblique, rim-unicyclic,
MetricsLith size: 1->12µm;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

See also: Reticulofenestra perplexa - name used for forms with closed central area;

Geological Range:
Notes: Common in the Mioene and Pliocene. In the Paleogene similar species occur but are conventionally assigned to different species, placed here in the R. umbilicus group. Replaced in the Late Pliocene and Quaternary by Pseudoemiliania, Gephyrocapsa and Emiliania.
Last occurrence (top): in mid part of Ionian Stage (52% up, 0.4Ma, in Ionian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Ypresian Stage (67% up, 50.5Ma, in Ypresian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Young, J. R. (1990). Size variation of Neogene Reticulofenestra coccoliths from Indian Ocean DSDP cores. Journal of Micropalaeontology. 9: 71-86. gs


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R. pseudoumbilicus group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-9-2019

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1149 Go to Archive.is to create a permanent copy of this page - citation notes



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