Taxonomic discussion: This is the first species of the genus Globanomalina to appear in the earliest Danian. In morphology it is very similar to its ancestral species, Hedbergellaholmdelensis Olsson, 1964. It differs, however, in that fine pustules are confined to the umbilical and inner spiral areas of the test rather than being sparsely distributed over the entire wall of the test as in H. holmdelensis. In early species of Globanomalina the chamber walls are smoother and generally free of numerous pustules. Pustules are more numerous on the chamber walls of G. pseudomenardii, but these are enhanced by gametogenesis. The possibility that the "pustules" in G. archeocompressa are of similar origin needs further investigation. The chambers are somewhat more inflated and the equatorial peripheral margin is more lobulate in H. holmdelensis. Another difference lies in the ontogeny of each species. Six to 7 chambers make up the penultimate whorl in H. holmdelensis, a chamber arrangement typical of ancestral species of Hedbergella in the Cretaceous. In G. archeocompressa, the penultimate whorl is reduced to 5 chambers, which is typical of Globanomalina. The imperforate peripheral margin is a primary derived taxonomic character from H. holmdelensis and is present throughout the archeocompressa lineage. [Olsson et al. 1999]
Distinguishing features: Parent taxon (Globanomalina): 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. This taxon: 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.
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: 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. [Olsson et al. 1999]
Character matrix
test outline:
Ovate
chamber arrangement:
Trochospiral
edge view:
Concavo-convex
aperture:
Umbilical-extraumbilical
sp chamber shape:
Inflated
coiling axis:
Low
periphery:
N/A
aperture border:
Thick flange
umb chbr shape:
Inflated
umbilicus:
Wide
periph margin shape:
Moderately rounded
accessory apertures:
None
spiral sutures:
Moderately depressed
umb depth:
Shallow
wall texture:
Smooth
shell porosity:
Finely Perforate: 1-2.5µm
umbilical or test sutures:
Moderately depressed
final-whorl chambers:
5-6
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionWestern equatorial Pacific Ocean, coastal Gulf of Mexico, and South Atlantic Ocean (DSDP Site 356). [Olsson et al. 1999]
Aze et al. 2011 summary: Western equatorial pacific, Gulf of Mexico, south Atlantic Ocean; based on Olsson et al. (1999) Isotope paleobiologyNo data available. [Olsson et al. 1999] Aze et al. 2011 ecogroup 3 - Open ocean thermocline; based on comparison with other species of the genus. Phylogenetic relationsThis species evolved from Hedbergellaholmdelensis in late Biochron P0. [Olsson et al. 1999]
Biostratigraphic distribution
Geological Range: Notes: Upper Zone P0 to Zone Plb. Due to the very small size and rare occurrence of this species the upper range is not yet reliably established. [Olsson et al. 1999] Last occurrence (top): at top of P1b subzone (100% up, 63.9Ma, in Danian stage). Data source: Olsson et al. 1999 First occurrence (base): in mid part of P0 zone (50% up, 66Ma, in Danian stage). Data source: Olsson et al. 1999
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
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
Taxon plotted: Globanomalina archeocompressa, synonyms included - Globanomalina archeocompressa;
Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 37
References:
Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. 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 archeocompressa compiled by the pforams@mikrotax project teamviewed: 9-2-2026
Olsson_etal_99_pl32_f08-10.jpg
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Olsson_etal_99_pl32_f08-10.jpg
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Olsson_etal_99_pl32_f01-4.jpg/Globorotalia (Turborotalia) archeocompressa/Blow79 pl056 01-2.JPG)
paratype: G. (Turborotalia) archeocompressa/Globorotalia (Turborotalia) archeocompressa/Blow79 pl064 05 9.JPG)
paratype: G. (Turborotalia) archeocompressa/Globorotalia (Turborotalia) archeocompressa/Blow79 pl068 05-6.JPG)
paratype: G. (Turborotalia) archeocompressa/Globorotalia (Turborotalia) archeocompressa/Blow79 pl058 02 6-7.JPG)
x: G. (Turborotalia) archeocompressa/Globorotalia (Turborotalia) archeocompressa/Blow79 pl058 08-9.JPG)
x: G. (Turborotalia) archeocompressa
