Globanomalina


Classification: pf_cenozoic -> smooth non-spinose -> Hedbergellidae -> Globanomalina
Sister taxa: Globanomalina, Hedbergella, Planoglobanomalina, Pseudohastigerina, Turborotalia,
Daughter taxa (blue => in age window 0-300Ma)
This is a very small-sized species, being less than 130 um in greatest diameter. It has a flattened compressed test with the spiral side being nearly plane. The axial periphery is rounded with slightly conical chambers which are nearly flat on the spiral side and project at a high angle towards the umbilicus. Five to six, compressed oval-shaped chambers that increase very gradually in size make up the ultimate whorl. The umbilicus is shallow and broad, open to the previous chambers, and contains sparse pustules on the umbilical shoulders of the surrounding chambers. The umbilical-extraumbilical aperture is a broad, low arch which is bordered throughout its extent by a narrow lip. The wall, which ranges from 4 to 7 um in thickness, is smooth and perforate. The pores which average 1 um at the narrowest point are mostly confined to the chamber surfaces away from the periphery which is largely imperforate.
This small species is distinguished by having 4 low conical shaped chambers in the ultimate whorl and an acute axial periphery. The earlier chamber walls are covered by a fine, dense pustules which become more sparsely distributed on the penultimate and ultimate chambers. The axial periphery is imperforate for the most part and becomes thickened on the last one or two chambers.
This species is identified by its compressed test, pinched periphery with a thickened imperforate band, and the rapidly enlarging chambers. The number of chambers in the ultimate whorl is typically 5 but can range up to 6. The test walls are smooth with occasional small pustule buildups in the umbilical area and on the inner spiral area.
A small, 5 chambered smooth-walled test, with a moderately angular axial periphery, and with an imperforate peripheral margin that is moderately to strongly developed. Aperture a low, umbilical-extraumbilical arch, bordered along its entire extent by a narrow well defined lip.
Compressed, smooth-walled test, with chambers moderately increasing in size, often with the ultimate chamber smaller than the penultimate one, pinched periphery that has a thickened imperforate margin (faint keel of Bolli), 5-5½ chambers in the ultimate whorl.
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.
Globanomalina luxorensis is characterized by its very low trochospiral test, globular chambers, rounded axial periphery, and an arched aperture that extends over the axial periphery to the spiral side, but not to the trace of the spiral suture. The species is regarded as representing the transitional morphology from a trochospiral to a planispiral test, but is not planispiral according to the criterion of Blow (1979, p. 1060; discussed above).

The five chambers in the ultimate whorl increase moderately in size. The chambers are more inflated than in G. archeocompressa and globular to ovoid in shape. The pores which average 1 um at the narrowest point are evenly distributed in the chamber walls although some areas, especially on parts of the periphery, are imperforate. The wall ranges from 4 to 7 um in thickness.
A small highly compressed species with a well developed, thickened, imperforate peripheral margin. The number of chambers in the ultimate whorl ranges from 5 to 6, occasionally 7. The aperture is a high umbilical-extraumbilical arch that is bordered by a thin continuous lip. The equatorial periphery is rounded in the early portions of the ultimate whorl and becomes more lobulate with the final few chambers.
The distinct keel, the sharply-angled axial periphery, spiroconvex test, and narrow umbilicus are distinguishing features. The number of chambers in the ultimate whorl is consistently 5, but rarely a 6 chambered form is observed.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Globanomalina Haque, 1956
Rank: Genus
Type species: Globanomalina ovalis Haque, 1956
Synonyms:
Taxonomic discussion: Banner's 1989 study of Globanomalina clarified its taxonomic status, clearly distinguishing the genus from the planispiral Pseudohastigerina, which Loeblich and Tappan (1988) regarded as a junior synonym of this genus. Banner emended the genus to clearly separate it from Pseudohastigerina and discussed its evolutionary relationship with this genus. He, however, regarded Globanomalina as having a microperforate wall with low, bluntly margined perforation pits. His observations appear to be based on poorly preserved specimens with corroded and recrystallized walls. All of the species of Globanomalina included in this atlas are normal perforate. Banner's observation of perforation pits is, however, correct, but as he pointed out, they are not to be confused with a cancellate wall. Globanomalina is herein emended to include the smooth-walled species of the Paleocene, which are members of two distinct lineages, one with an imperforate margin that leads to the carinate species G. pseudomenardii and one with a perforate margin that leads to the planispiral genus Pseudohastigerina. [Olsson et al. 1999]

Catalog entries: Globanomalina; Pseudomenardella;

Type images:

Short diagnosis: Test very low trochospiral with 12-15 chambers, with 5-6 chambers in ultimate whorl; chambers vary from globular to ovoid to low conical in shape. Aperture interiomarginal, umbilical-extraumbilical, a moderately high arch bordered by narrow lip that may broaden slightly towards umbilicus; aperture may extend slightly onto spiral side. Umbilicus small, generally deep. Wall normal perforate, smooth, but may be covered with pustule growth in some species, particularly in umbilical area. Peripheral margin either perforate, an imperforate band, or keeled. [Olsson et al. 1999]

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.

Description


Diagnostic characters: Test very low trochospiral with 12-15 chambers, with 5-6 chambers in ultimate whorl; chambers vary from globular to ovoid to low conical in shape. Aperture interiomarginal, umbilical-extraumbilical, a moderately high arch bordered by narrow lip that may broaden slightly towards umbilicus; aperture may extend slightly onto spiral side. Umbilicus small, generally deep. Wall normal perforate, smooth, but may be covered with pustule growth in some species, particularly in umbilical area. Peripheral margin either perforate, an imperforate band, or keeled. [Olsson et al. 1999]

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Priabonian Stage (33.89-37.75Ma, top in Priabonian stage). Data source: Total of range of species in this database
First occurrence (base): within Danian Stage (61.61-66.04Ma, base in Danian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 37

References:

Haque, A.F.M.M., (1956). The smaller foraminifera of the Ranikot and the Laki of the Nammal gorge, Salt Range. Memoir of the Pakistan Geological Survey, 1: 1-300.

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.


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Globanomalina compiled by the pforams@mikrotax project team viewed: 21-8-2017

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