Globoquadrina praedehiscens

NB TAXA WHICH ORIGINATE IN THE OLIGOCENE ARE NOT INCLUDED YET
Classification: pf_neogene -> Globorotalidae -> Globoquadrina -> Globoquadrina praedehiscens
Sister taxa: G. conglomerata, G. dehiscens, G. praedehiscens,

Taxonomy

Citation: Globoquadrina praedehiscens Blow & Banner 1962
Rank: species
Basionym: Globoquadrina dehiscens praedehiscens Blow & Banner 1962
Similar species: Gq. praedehiscens is distinguished from Gq. dehiscens by possessing a more rounded and less quadrate test, three chambers in the final whorl, and a lower and narrower apertural face, which directly faces the umbilicus. This species differs from Gq. venezuelana in having 3 instead of 4 chambers in the final whorl and in having the chambers of the final whorl laterally more compressed. [Kennett & Srinivasan 1983]

Catalog entries: Globoquadrina dehiscens praedehiscens;

Type images:

Description


Test morphology: Test large, equatorial periphery slightly lobulate, chambers spherical, those of final whorl strongly laterally compressed; three in the final whorl, increasing very rapidly in size as added; spiral sutures curved, depressed; umbilical sutures , radial, depressed , surface coarsely perforate; umbilicus narrow to fairly wide; aperture interiomarginal, umbilical, with distinct umbilical tooth. [Kennett & Srinivasan 1983]

Biogeography and Palaeobiology


Geographic distribution: Tropical to warm subtropical. [Kennett & Srinivasan 1983]

Phylogenetic relations: Although Gq. praedehiscens shows an intraumbilical aperture like Dentoglobigerina, it is phyletically unrelated to that genus. On the other hand, its placement in Globoquadrina is justified since it morphologically grades into Gq. dehiscens, the type species of Globoquadrina. Gq. praedehiscens descended from Gq. sellii in the latest Oligocene and is ancestral to Gq. dehiscens. [Kennett & Srinivasan 1983]

Similar species: Gq. praedehiscens is distinguished from Gq. dehiscens by possessing a more rounded and less quadrate test, three chambers in the final whorl, and a lower and narrower apertural face, which directly faces the umbilicus. This species differs from Gq. venezuelana in having 3 instead of 4 chambers in the final whorl and in having the chambers of the final whorl laterally more compressed. [Kennett & Srinivasan 1983]

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within N6 zone (17.54-17.59Ma, top in Burdigalian stage). Data source: Kennett & Srinivasan 1983
First occurrence (base): within P22 zone (23.50-26.93Ma, base in Chattian stage). Data source: Kennett & Srinivasan 1983

Plot of occurrence data:

Primary source for this page: Kennett & Srinivisan 1983, p.182

References:

Blow, W.H. & Banner, F.T., (1962). The mid-Tertiary (Upper Eocene to Aquitanian) Globigerinaceae. In: Eames, F.E. et al. (Editors), Fundamentals of mid-Tertiary Stratigraphical Correlation. Cambridge University Press, Cambridge, pp. 61-151.

Kennett, J.P. & Srinivasan, M.S., (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania, 1-265 pp.


Globoquadrina praedehiscens compiled by the pforams@mikrotax project team viewed: 23-5-2017

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