Praeorbulina glomerosa curva Blow 1956 from: Vincent, E.Toumarkine, M. (1990): Neogene planktonic foraminifers from the Western Tropical Indian Ocean, Leg 115. In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 115 Eds: Duncan, R.A..Backman, J.Peterson, L.C. p. 795-836 . |
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Subspecies Praeorbulina glomerosa curva Blow 1956 |
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Diagnosis / Definition: |
Kennett & Srinivasan (1983):
Test large, subspherical to spherical, last chamber subglobular, inflated and embracing between 40 to 70 percent of the earlier test; surface coarsely perforate; sutures
slightly curve to radial, depressed; primary aperture of the early portion is covered by the final embracing chamber, which has four to eight small, sutural, supplementary apertures. |
Discussion / Comments: |
Kennett & Srinivasan (1983):
Pr. glomerosa curva exhibits intermediate morphology between its ancestor Globigerinoides sicanus and its descendant
Pr. glomerosa glomerosa. It is distinguished from Globigerinoides in having an almost spherical test and in the more numerous supplementary apertures of the last chamber.
With the final chamber enveloping progressively more of the earlier portion and a concomitant increase in the number of slitlike supplementary apertures, this species changes
into Pr. glomerosa glomerosa.
The evolutionary appearance of Pr. glomerosa curva marks a distinct widespread datum in the late Early Miocene.
Bolli & Saunders (1985):
P. glomerosa glomerosa differs from P. glomerosa curva in having more apertures around the base of the last chamber and in possessing a test that is almost spherical in outline due to the high degree of envelopment by the last chamber. |
Synonym list: |
Kennett & Srinivasan (1983):
Bolli & Saunders (1985):
Vincent & Toumarkine (1990):
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References: |
Blow,W.H. (1956): Origin and evolution of the foraminiferal genus Orbulina d'Orbigny . Micropaleontology Vol. 2(1) p. 57-70
Kennett,J. and Srinivasan,M.S. (1983): Neogene Planktonic Foraminifera - A Phylogenetic Atlas.
Bolli,H.M. and Saunders,J.B. (1985): Oligocene to Holocene low latitude planktic foraminifers. In: Plankton Stratigraphy Eds: Bolli, H.M.Saunders, J.B. p. 155-262
Vincent,E. and Toumarkine,M. (1990): Neogene planktonic foraminifers from the Western Tropical Indian Ocean, Leg 115. In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 115 Eds: Duncan, R.A..Backman, J.Peterson, L.C. p. 795-836
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