- divided into two main lineage groups and within these ordered by FO (time control age-window is: 0-800Ma)
lineage group B - inflated chambers, perforate walls
Globanomalina australiformis Test small. Final whorl with 4 low conical chambers and an acute axial periphery. Axial periphery imperforate, becoming thickened on the last chambers.
Globanomalina luxorensis Test very low trochospiral. Chambers globular. Axial periphery rounded. Aperture arched, extending over axial periphery to spiral side, but not to the trace of the spiral suture.
Globanomalina ovalis 5-6 inflated chambers in the final whorl, very low coiling axis.
Globanomalina imitata Test small. Final whorl with 4-4½ (rarely 5) inflated ovoid chambers. Aperture a high umbilical-extraumbilical arch with thin continuous lip.
Globanomalina planocompressa 5 chambers in the final whorl, increasing moderately in size. The chambers are more inflated than in G. archeocompressa and globular to ovoid.
lineage group A - compressed tests, imperforate margin
Globanomalina planoconica Test small highly compressed, with well-developed, thickened, imperforate peripheral margin. Final whorl with 5-6 (rarely 7) chambers, equatorial periphery rounded becoming lobulate. Aperture high umbilical-extraumbilical arch with thin, continuous lip.
Globanomalina chapmani Test compressed, periphery pinched with a thickened imperforate band. 5-6 rapidly enlarging chambers in final whorl.
Globanomalina pseudomenardii Test spiroconvex with distinct keel & sharply-angled axial periphery. Umbilicus narrow. 5 (rarely 6) chambers in final whorl.
Globanomalina ehrenbergi Test compressed, smooth-walled, chambers moderately increasing in size. Periphery pinched with a thickened imperforate margin (faint keel). 5-5½ chambers in final whorl.
Globanomalina compressa Test small, 5 chambered, with moderately angular axial periphery, and with an imperforate peripheral margin that is moderately to strongly developed. Aperture a low, umbilical-extraumbilical arch, with a narrow well-defined lip.
Globanomalina archeocompressa Test very small (<130 µm), flattened, with the spiral side nearly flat. Axial periphery rounded with slightly conical chambers. Final whorl with 5-6, chambers that increase very gradually in size. Umbilicus shallow and broad, open to the previous chambers. Aperture umbilical-extraumbilical, broad, low arch with narrow lip.
Globanomalina sp. Specimens which cannot be assigned to established species
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]
Distinguishing features: Parent taxon (Globanomalinidae): Hedbergellids - trochospiral, mostly low trochospiral. Apertures of earlier formed chambers remain visible around the umbilicus. This taxon: Very low trochospiral; 5-6 chambers in final whorl; chamber-shape variable. Aperture interiomarginal, umbilical-extraumbilical, arch with narrow lip. Wall smooth, normally perforate, pustules in some species.
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
Biogeography and Palaeobiology
Biostratigraphic distribution
Geological Range: Last occurrence (top): at top of E9 zone (100% up, 43.2Ma, in Lutetian stage). Data source: Total of ranges of the species in this database First occurrence (base): within P0 zone (66.00-66.04Ma, base in Danian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 37
References:
Banner, F. T. (1989). The nature of Globanomalina Haque, 1956. Journal of Foraminiferal Research. 19: 171-179. gs
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. gs
Loeblich, A. R. & Tappan, H. (1988). Foraminiferal Genera and Their Classification (Volume I-II). Van Nostrand Reinhold Co., New York. 1-1059. gs
Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. (85): 1-252. gs
Globanomalina compiled by the pforams@mikrotax project teamviewed: 14-10-2024
