Distinguishing features: Parent taxon (Globigerinoides): Supplementary apertures, with ruber/sacculifer-type spinose wall texture This taxon: Like G. subquadratus, but very small, compact test. Apertures almost circular, symmetrically above sutures.
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.
Aperture: Primary aperture interiomarginal umbilical small circular symmetrical arch. Supplementary sutural apertures on spiral side [Aze 2011, based on Kennett & Srinivasan 1983]
Morphology: Test small, trochospiral, equatorial periphery subquadrate, chambers spherical in early stages, later becoming laterally compressed; three chambers in the final whorl, increasing moderately in size; sutures on both spiral and umbilical side radial and depressed; surface distinctly cancellate; umbilicus small, primary aperture interiomarginal, umbilical small, almost circular symmetrically above the suture line of the two earlier chambers ; supplementary sutural apertures, generally two situated over the sutures of earlier chambers. [Kennett & Srinivasan 1983] Wall type: Spinose; Cancellate [Aze 2011]
Character matrix
test outline:
Subcircular
chamber arrangement:
Trochospiral
edge view:
Equally biconvex
aperture:
Umbilical
sp chamber shape:
Globular
coiling axis:
Low-moderate
periphery:
N/A
aperture border:
N/A
umb chbr shape:
Globular
umbilicus:
Wide
periph margin shape:
Broadly rounded
accessory apertures:
Sutural
spiral sutures:
Strongly depressed
umb depth:
Deep
wall texture:
Cancellate
shell porosity:
Macroperforate: >2.5µm
umbilical or test sutures:
Strongly depressed
final-whorl chambers:
3-3
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionTropical [Kennett & Srinivasan 1983] Low latitudes [Aze et al. 2011, based on Kennett & Srinivasan (1983)]
[SCOR WG138]
Isotope paleobiologyAze et al. 2011 ecogroup 1 - Open ocean mixed-layer tropical/subtropical, with symbionts. Based on very heavy δ13C and relatively light δ18O. Sources cited by Aze et al. 2011 (appendix S3): Keller (1985) Phylogenetic relationsThe position of the apertures symmetrically above the sutures between two earlier chambers, the subquadrate shape of the test, and the cancellate surface in both the Gs. diminutus and Gs. subquadratus suggest a close phylogenetic relationship between these two forms. Gs. diminutus is distinguished from Gs. subquadratus by its very small size and more compact test. Possibly Gs. diminutus represents a tropical variant of Gs. subquadratus. [Kennett & Srinivasan 1983]
Most likely ancestor: Globigerinoides subquadratus - at confidence level 3 (out of 5). Data source: Kennett & Srinivasan 1983, fig. 10.
Biostratigraphic distribution
Geological Range: Last occurrence (top): within N9 zone (14.24-15.10Ma, top in Langhian stage). Data source: Kennett & Srinivasan 1983 First occurrence (base): within N7 zone (16.38-17.54Ma, base in Burdigalian stage). Data source: Kennett & Srinivasan 1983
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: Globigerinoides diminutus, synonyms included - Globigerinoides diminutus;
Primary source for this page: Kennett & Srinivasan 1983, p.74
References:
Aze, T., et al. (2011). A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data. Biological Reviews. 86: 900-927. gs
Bolli, H. M. (1957b). Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I. 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: 97-123. gs
Keller, G. (1985). Depth stratification of planktonic foraminifers in the Miocene Ocean. In, Kennett, J. P. (ed.) The Miocene Ocean: Paleoceanography and Biogeography. GSA Memoir . 163: 1-337. gs
Kennett, J. P. & Srinivasan, M. S. (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. gs
Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. gs
Globigerinoides diminutus compiled by the pforams@mikrotax project teamviewed: 17-6-2026