R. lockeri group


Classification: Coccolithophores -> Isochrysidales -> Noelaerhabdaceae -> Reticulofenestra -> R. lockeri 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)
medium sized (ca 5-10µm), central-area with a plug surrounded by ring of pores.
Elliptical with broad central area filled by robust, but coarsely perforated, plate. Perforations visible in LM
Elliptical reticulofenestrid with wide central area spanned by a birefringent central area net. Perforations not visible in lm.
Small with wide central area, net thicker in centre
Large to very large (>10 µm) with wide cenral area, net weakly visible in LM
Very small (<3µm), normally elliptical reticulofenestrid with narrow rim and wide central area spanned by a relatively robust grill.

Taxonomy:

Citation: R. locker group
Rank: species group
Notes & discussion: Species included here follow Bown & Newsam (2017) and Boesiger et al. (2017). However, we do not follow renaming suggstions of Boesiger et al. (2017) since we disagree with their interpretations of EM images of type specimens. Specifically Boesiger et al. (2017) reccommend separating three morphotypes in the Oligocene and Early Miocene interval as outlined in the table below which also indicates the names suggested by Boesiger et al. (2017) and those adopted here.
LM appearance traditional name Boesiger et al 2017 name adopted name range 
imperforate lockeri albitectus lockeri NP18-NN4
marginal ring of perforations daviesii onustus daviesii NP12-NN4
numerous small perforations   gartneri gartneri NP12-NP23

Distinguishing features: Elliptical reticulofenestrids with relatively open central area spanned on the proxmal surface by a robust grill (clearly visible in lm as a birefringent plate with variable number of perforations).

Farinacci & Howe catalog pages:

Search data:
Tags
CSPH: spherical, V-UNITS: none, R-UNITS: all, c-str, distal shield, prox shield, tube, DETAILS: isogyres kinked, isogyres oblique,
MetricsLith size: 2->14µm;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Notes: Common, upper Eocene-upper Oligocene.
Last occurrence (top): in lower part of Burdigalian Stage (32% up, 19Ma, in Burdigalian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Ypresian Stage (0% up, 56Ma, in Ypresian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P. R. & Dunkley Jones, T. (2012). Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research. 32(2): 3-51. gs :: view :: open

Bown, P. R. & Newsam, C. (2017). Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411). Journal of Nannoplankton Research. 37(1): 25-60. gs :: view :: open


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R. lockeri group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 29-5-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1147 Go to Archive.is to create a permanent copy of this page - citation notes



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