Globigerina ampliapertura Bolli 1957 from: Bolli, H.M. (1957): Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I.. In: Studies in Foraminifery, Bulletin of the U.S. National Museum Vol. 215 Eds: Loeblich, A.R.Tappan, H.Beckmann, J.P.Bolli, H.M.Gallitelli, E.M.Troelsen, J.C. p. 97-123 . |
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Species Globigerina ampliapertura Bolli 1957 |
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Diagnosis / Definition: |
Bolli (1957):
Shape of test trochospiral; spiral side almost flat to slightly convex, umbilical side convex; equatorial periphery lobate; axial periphery rounded. wan calcareous, perforate, surface finely pitted. Chambers spherical in the early stage, becoming somewhat compressed laterally in the last whorl; about 12, arranged in 2 1/2 whorls; the usually 4 chambers of the last whorl increase rapidly in size. Sutures on spiral side radial to oblique, depressed; on umbilical side radial, depressed. Umbilicus fairly small, deep. Aperture a high, distinct arch; interiomarginal, umbilical. Coiling random. Largest diameter of holotype 0.55 mm. |
Discussion / Comments: |
Bolli (1957):
Globigerina ampliapertura, new species, is distinguished from G. venezuelana in having a larger, distinctly arched aperture. It differs from G. apertura Cushman, which was described from the Miocene, in having the chambers of the last whorl somewhat compressed laterally and in the aperture being smaller in relation to the chamber size. The G. apertura mentioned by Bronnimann (1950, p. 80) from the Cipero formation is a G. ampliapertura. The new species occurs also in the upper Eocene. Globigerina ampliapertura, which appears in the uppermost Eocene and continues into the basal Oligocene, seems to be genetically related to Globorotalia centralis Cushman and Bermudez. Intermediate forms (USNM P5719a,b) showing the aperture in a transitional position, are commonly found in the Globorotalia cocoaensis zone (pl. 36, figs. 9, 10). The species might represent a gerontic stage of the G. centralis G. cocoaensis strain, 7 reverting before its ex¬tinction to a globigerinid form and also to random
coiling.
Van Eijden & Smit (1991):
Remarks. This distinct marker species is rare in early Oligocene faunas.
Spezzaferri & Silva (1990):
Typical specimens are very rare. Wall surface of
this taxon is cancellate, possibly spinose (see Blow
and Banner, 1962), then its generic attribution is
still uncertain. |
Systematics: |
22 Genus Dentoglobigerina
Species Globigerina ampliapertura
24 Genus Globigerina
Species Globigerina ampliapertura
32 Ordo Foraminiferida
Familia Globigerinidae
Genus Globigerina
Species Globigerina ampliapertura
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Synonym list: |
Bolli (1957):
Bolli (1957):
Van Eijden & Smit (1991):
Spezzaferri & Silva (1990):
Quilty (1976):
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Was used in synonym list of: |
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References: |
Bolli,H.M.; Loeblich,A.R. and Tappan,H. (1957): The Planktonic foraminiferal families Hantkeninidae, Orbulinidae, Globorotaliidae, and Globotruncanidae . U.S. National Museum Bull. Vol. 215 p. 3-50
Bolli,H.M. (1957): Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I.. In: Studies in Foraminifery, Bulletin of the U.S. National Museum Vol. 215 Eds: Loeblich, A.R.Tappan, H.Beckmann, J.P.Bolli, H.M.Gallitelli, E.M.Troelsen, J.C. p. 97-123
Bolli,H.M. (1957): Planktonic Foraminifera from the Eocene Navet and San Fernando formations of Trinidad, B.W.I. . Bull. U.S. natl. Mus. Vol. 215 p. 155-172
Quilty,P.G.. (1976): Planctonic foraminifera DSDP Leg 34- Nazca Plata . DSDP initial reports Vol. 34
Spezzaferri,S. and Silva,I.S.. (1990): Oligocene planktonic foraminiferal biostratigraphy and paleoclimatic interpretation from Hole 538A, DSDP Leg 77, Gulf of Mexico . Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 83 p. 217-263
Van Eijden,A.J.M. and Smit,J. (1991): Eastern Indian Ocean Cretaceous and Paleogene quantitative biostratigraphy. In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 121 Eds: Weissel, J.Peirce, J.Taylor, E.Alt, J. p. 77-123
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