Globorotalia margaritae


Classification: pf_cenozoic -> Globorotaliidae -> Globorotalia -> hirsuta lineage -> Globorotalia margaritae
Sister taxa: G. hirsuta, G. theyeri, G. margaritae, G. juanai, G. bermudezi, G. scitula, G. praescitula, G. cibaoensis, G. gigantea, G. challengeri,
Daughter taxa: : Variants - not recognised by all workers (blue => in age window 0-800Ma)
larger and with a more symmetrical profile
smaller and lacks a complete keel

Taxonomy

Citation: Globorotalia margaritae Bolli & Bermudez 1965
Rank: species
Basionym: Globorotalia margaritae
Synonyms:

Catalog entries: Globorotalia margaritae

Type images:

Distinguishing features: Like G. juanai & scitula, but more convexly rounded spiral side and concave to flat umbilical side; more delicate peripheral keel, and in the distinctly elongate, narrower, and more strongly curved chambers on spiral side.

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, compressed, spiral side convex, umbilical side concave with thin keel

Aperture: Interiomarginal umbilical-extraumbilical low slit bordered by a pronounced lip [Aze 2011, based on Kennett & Srinivasan 1983]


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

Test morphology: Test low trochospiral, compressed, spiral side convex, umbilical side concave to almost flat, equatorial periphery slightly lobulate, axial periphery acute with a thin keel; chambers strongly compressed, 5 in the final whorl, increasing rapidly in size; sutures on spiral side strongly curved, limbate, slightly raised, on umbilical side gently curved, depressed; surface coarsely and densely perforate, early chambers slightly pustulose, later chambers smooth. Umbilicus narrow; aperture a low slit bordered by a pronounced lip, interiomarginal, extraumbilical-umbilical. [Kennett & Srinivasan 1983]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Equally 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:5.0-5.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


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

[SCOR WG138]


Isotope paleobiology: Aze et al. 2011 ecogroup 4 - Open ocean sub-thermocline. Based on comparison with other species of the genus

Phylogenetic relations: Gr. (H.) margaritae differs from its ancestral forms Gr. (H.) scitula and Gr. (H.) juanai by its more convexly rounded spiral side and concave to flat umbilical side, in its more delicate peripheral keel, and in the distinctly elongate, narrower, and more strongly curved chambers as viewed from the spiral side.
Gr. (H) margaritae evolved from Gr. (H.) juanai by an increase in chamber numbers in the final whorl and by development of a convexly rounded spiral side and a relatively narrow keel. This species is ancestral to Gr. (H) theyeri Fleisher and Gr. (H) hirsuta (d'Orbigny). [Kennett & Srinivasan 1983]

Most likely ancestor: Globorotalia juanai - at confidence level 3 (out of 5). Data source: Kennett & Srinivasan 1983, fig 15; Stewart 2003 fig. 6.10; Aze et al. 2011, appendix 5.
Likely descendants: Globorotalia evoluta; Globorotalia theyeri;

Biostratigraphic distribution

Geological Range:
Notes: Gr. (H) margaritae has a short stratigraphic range and is a generally recognized index species for the tropical to temperate Early Pliocene (Bolli, 1970; Srinivasan et al.,1981) .
Last occurrence (top): at top of PL2 zone (100% up, 3.9Ma, in Zanclean stage). Data source: Wade et al. (2011), zonal marker
First occurrence (base): near base of M14 [Atl.] zone (14% up, 6.1Ma, in Messinian stage). Data source: Wade et al. (2011), additional event; position within zone determined by linear interpolation from data in table 1 of Wade et al. (2011).

Plot of occurrence data:

Primary source for this page: Kennett & Srinivasan 1983, p.136

References:

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

Bolli, H. M. & Bermudez, P. J. (1965). Zonation based on planktonic foraminifera of middle Miocene to Pliocene warm-water sediments. Bol. Informativo, Asoc. Venez. Geol., Min. Petrol.. 8(5): 121-149. gs

Cita, M. B. (1973). Pliocene biostratigraphy and chronostratigraphy. Initial Reports of the Deep Sea Drilling Project. 13: 1343-1379. gs

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

Norris, R. D. (1998). Planktonic foraminifer biostratigraphy: Eastern Equatorial Atlantic. Proceedings of the Ocean Drilling Program, Scientific Results. 159: 445-479. gs

Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. gs


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Globorotalia margaritae compiled by the pforams@mikrotax project team viewed: 20-9-2019

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