Globorotalia merotumida


Classification: pf_cenozoic -> Globorotaliidae -> Globorotalia -> tumida lineage -> Globorotalia merotumida
Sister taxa: G. ungulata, G. flexuosa, G. tumida, G. plesiotumida, G. merotumida,

Taxonomy

Citation: Globorotalia merotumida Blow & Banner, in Banner & Blow 1965
Rank: species
Basionym: Globorotalia (Globorotalia) merotumida
Synonyms:

Catalog entries: Globorotalia (Globorotalia) merotumida

Type images:

Distinguishing features: Low trochospiral, biconvex, equatorial periphery slightly lobate with distinct keel Aperture:a low arch with thick lip. Final chamber is wider than the high.

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.
They are being edited as the site is developed and comments on them are especially welcome.

Description


Diagnostic characters: Low trochospiral, biconvex, equatorial periphery slightly lobate with distinct keel

Aperture: Interiomarginal umbilical-extraumbilical low arch with thick lip [Aze 2011, based on Kennett & Srinivasan 1983]


Wall type: Non-spinose; Smooth [Aze 2011]

Test morphology: Test very low trochospiral, biconvex, equatorial periphery slightly lobulate, axial periphery acute with a distinct keel; 5 to 6 wedge-shaped chambers in the final whorl; chambers more inflated on umbilical side than on spiral side; spiral sutures limbate, slightly raised, thickened, curved, merging with the keel; on umbilical side gently curved to radial depressed; surface smooth, densely perforate, slightly pustulate near the aperture or umbilical side; umbilicus narrow, aperture interiomarginal, umbilical-extraumbilical, low arch with a thick lip. [Kennett & Srinivasan 1983]

Character matrix

test outline:Ovatechamber arrangement:Trochospiraledge view:Inequally biconvexaperture:Umbilical-extraumbilical
sp chamber shape:Crescenticcoiling axis:Lowperiphery:Single keelaperture border:Thick lip
umb chbr shape:Subtriangularumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:None
spiral sutures:Raisedumb depth:Shallowwall texture:Smoothshell porosity:Macroperforate: >2.5µm
umbilical or test sutures:Weakly depressedfinal-whorl chambers:5.0-6.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Tropical to warm subtropical. [Kennett & Srinivasan 1983] Low latitudes [Aze et al. 2011, based on Kennett & Srinivasan (1983)]

[SCOR WG138]


Isotope paleobiology: Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light ∂13C and relatively heavy ∂18O. Sources cited by Aze et al. 2011 (appendix S3): this study

Phylogenetic relations: Gr. (Gr.) merotumida differs from Gr. (Gr.) paralenguaensis in having a distinct keel and limbate sutures on the spiral side. It is distinguished from Gr. (Gr.) plesiotumida by its smaller size, slightly more convex umbilical side, less ovate equatorial profile, and the height and width of the final chamber (in merotumida the final chamber is wider than the height).
Gr. (Gr.) merotumida evolved from Gr. (Gr.) paralenguaensis in the early part of Zone N16 (Late Miocene) and is ancestral to Gr. (Gr.) plesiotumida. [Kennett & Srinivasan 1983]

Similar species:

Most likely ancestor: Globorotalia menardii - at confidence level 3 (out of 5). Data source: Stewart 2003 fig. 6.10; Aze et al. 2011, appendix 5. NB This differs markedly from Kennett & Srinivasan, who suggested ancestor was G. paralenguaensis.
Likely descendants: Globorotalia plesiotumida;

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within N18 zone (5.20-5.72Ma, top in Zanclean stage). Data source: Chaisson & Pearson (1997)
First occurrence (base): within N16 zone (8.58-9.83Ma, base in Tortonian stage). Data source: Chaisson & Pearson (1997)

Plot of occurrence data:

Primary source for this page: Kennett & Srinivasan 1983, p.154

References:

Aze, T. et al. (2011). A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data. Biological Reviews. 86: 900-927. gs

Banner, F. T. & Blow, W. H. (1965c). Two new taxa of the Globorotaliinae (Globigerinacea, foraminifera) assisting determination of the late Miocene/middle Miocene boundary. Nature. 207(5004): 1351-1354. gs

Chaisson, W. P. & Pearson, P. N. P. (1997). Planktonic foraminifer biostratigraphy at Site 925: Middle Miocene–Pleistocene. Proceedings of the Ocean Drilling Program, Scientific Results. 154: 3-31. gs V O

Kennett, J. P. & Srinivasan, M. S. (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. gs


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Globorotalia merotumida compiled by the pforams@mikrotax project team viewed: 28-9-2020

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