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]
Catalog entries: Globorotalia (Turborotalia) archeocompressa
Type images: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.
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 |
Geographic distribution
Aze et al. 2011 summary: Western equatorial pacific, Gulf of Mexico, south Atlantic Ocean; based on Olsson et al. (1999)
Isotope paleobiology
Aze et al. 2011 ecogroup 3 - Open ocean thermocline; based on comparison with other species of the genus.
Phylogenetic relations
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:
Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 37
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. gsReferences:
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Globanomalina archeocompressa compiled by the pforams@mikrotax project team viewed: 7-2-2025
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