Globanomalina imitata


Classification: pf_cenozoic -> Globanomalidae -> 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.,

Taxonomy

Citation: Globanomalina imitata (Subbotina 1953)
Rank: Species
Basionym: Globorotalia imitata
Synonyms:
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:

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

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: 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:Ovatechamber arrangement:Trochospiraledge view:Planoconvexaperture:Umbilical-extraumbilical
sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Inflatedumbilicus:Narrowperiph margin shape:Moderately roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:Deepwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:4.0-5.0 N.B. These characters are used for advanced search. N/A - not applicable

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.
Likely descendants: Globanomalina australiformis; Globanomalina ovalis;

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

References:

Loeblich, A. R. & Tappan, H. (1957b). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In, Loeblich, A. R. , Jr. , Tappan, H. , Beckmann, J. P. , Bolli, H. M. , Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 173-198. gs

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. gs

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

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


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Globanomalina imitata compiled by the pforams@mikrotax project team viewed: 11-12-2019

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