Globanomalina imitata

Classification: pf_cenozoic -> smooth non-spinose -> Hedbergellidae -> Globanomalina -> Globanomalina imitata
Sister taxa: G. australiformis, G. luxorensis, G. ovalis, G. imitata, G. planocompressa, G. planoconica, G. chapmani, G. pseudomenardii, G. ehrenbergi, G. compressa, G. archeocompressa, G. sp.,


Citation: Globanomalina imitata (Subbotina 1953)
Rank: Species
Basionym: Globorotalia imitata
Taxonomic discussion: This is a distinctive species that is often overlooked because of its small size. It belongs to the perforate walled, inflated chamber lineage of planocompressa -imitata -ovalis. It also appears to have a phylogenetic link to G. australiformis (see "Discussion" under this species). The specimens illustrated as imitata by Blow (1979, pl. 81: figs. 8, 9, pl. 83: figs. 1,2, pl. 88:fig.5) are distinctly cancellate walled and do not belong to this species but probably belong to Praemurica. [Olsson et al. 1999]

Catalog entries: Globorotalia imitata;

Type images:

Short diagnosis: Test small. Final whorl with 4-4½ (rarely 5) inflated ovoid chambers. Aperture a high umbilical-extraumbilical arch with thin continuous lip.

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.


Diagnostic characters: A small smooth-walled test with 4 to 4½, occasionally 5, inflated chambers in the ultimate whorl. The chambers are ovoid in shape with the long axis directed towards the umbilicus. In spiral and umbilical view the chambers are ovoid in shape with the long axis parallel to the coiling spire. The test walls are perforate throughout and the aperture is a high umbilical-extraumbilical arch that is bordered by a thin continuous lip. The wall is smooth in the adult chambers, but is covered with fine scattered to dense pustules in the early ontogenetic stages which possess anguloconical chambers. [Olsson et al. 1999]

Character matrix

test outline:Ellipticalchamber arrangement:Trochospiraledge view:Planoconvexaperture:Interiomarginal
umb chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Thin lip
sp chbr shape:Inflatedumbilicus:Narrowperiph margin shape:Moderately roundedaccessory apertures:None
umbilical or test sutures:Moderately depressedumb depth:Deepwall texture:Smoothshell porosity:-
spiral sutures:Moderately depresseddiameter mm:0.15 - 0.25width mm:-breadth mm:0.08 - 0.11
final-whorl chambers:4.0-5.0

Biogeography and Palaeobiology

Geographic distribution: Known from the northern Caucasus, southeast India, and the Atlantic and Gulf of Mexico coastal plains. [Olsson et al. 1999]
Aze et al. 2011 summary: Northern Caucasus, S.E. India, Atlantic and Gulf of Mexico coastal plains; based on Olsson et al. (1999)

Isotope paleobiology: No data available. [Olsson et al. 1999]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light δ13C and relatively heavy δ18O. Sources cited by Aze et al. 2011 (appendix S3): this study

Phylogenetic relations: This species probably evolved from Globanomalina planocompressa in Zone Pic. [Olsson et al. 1999]

Most likely ancestor: Globanomalina planocompressa - at confidence level 4 (out of 5). Data source: Olsson et al. 1999, fig 5a.

Biostratigraphic distribution

Geological Range:
Notes: Zone Pic to Zone P4. [Olsson et al. 1999]
Last occurrence (top): near base of P5 zone (10% up, 57Ma, in Thanetian stage). Data source: Olsson et al. 1999, fig 5a
First occurrence (base): in upper part of P1c subzone (60% up, 63.1Ma, in Danian stage). Data source: Olsson et al. 1999, fig 5a

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 42


Loeblich, A.R., Jr. & Tappan, H., (1957). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 173-198.

Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Huber, B.T., (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Contributions to Paleobiology. Smithsonian Institution Press, Washington, DC, 1-252 pp.

Olsson, R.K., (1960). Foraminifera of late Cretaceous and earliest Tertiary age in the New Jersey Coastal Plain. Journal of Paleontology, 34(1): 1-58.

Subbotina, N., (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres, 2239: 1-144.


Globanomalina imitata compiled by the pforams@mikrotax project team viewed: 20-1-2018

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