Globigerina velascoensis Cushman 1925 from: Toumarkine, M.Luterbacher, H.P. (1985): Paleocene and Eocene Planktic Foraminifera. In: Plankton Stratigraphy p. 87-154 . |
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Species Globigerina velascoensis Cushman 1925 |
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Diagnosis / Definition: |
Bolli (1957):
Shape of test low trochospiral, spiral side often slightly concave, umbilical side strongly inflated; equatorial periphery strongly lobate; axial periphery rounded. Wall calcareous, perforate, surface smooth. Chambers inflated, subglobular, slightly compressed laterally, about 10, arranged in 2Y2 whorls, the 4 chambers of the last whorl increasing rapidly in size. Sutures on spiral side oblique, depressed; on umbilical side radial, depressed. Umbilicus narrow, partly covered by the lip of the last chamber. Apertures low arches, with distinct lips; interiomarginal, umbilical; the aperture of the ultimate chamber often tends to an extraumbilical unibilical position. Coiling random. Largest diameter of figured hypotype 0.33 mm. |
Discussion / Comments: |
Toumarkine & Luterbacher (1985):
The umbilical side of the compact test is inflated whereas the spiral side is flat or even somewhat depressed. The 4 chambers of the last whorl increase rapidly in size with the last one occupying almost one half of the whorl. The umbilicus is deep and narrow and the aperture in general has a distinct lip. The surface of the test is coarsely perforated, but rather smooth. The somewhat similar Acarinina primiliva has a strongly spinose to pustulose surface and a more compact aspect.
Bolli (1957):
Globigerina velascoensis Cushman apparently developed from G. triangularis White, from which it is distinguished by having the chambers of the last whorl slightly compressed laterally. Cushman's holotype of G. velascoensis is a poorly preserved and somewhat deformed specimen. The Lizard Springs types compare well with those of White (1928).
Van Eijden & Smit (1991):
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Systematics: |
15 Classis Foraminifera
Genus Globigerina
Species Globigerina velascoensis
20 Genus Globigerina
Species Globigerina velascoensis
32 Ordo Foraminiferida
Familia Globigerinidae
Genus Globigerina
Species Globigerina velascoensis
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Synonym list: |
Toumarkine & Luterbacher (1985):
Bolli (1957):
Van Eijden & Smit (1991):
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Was used in synonym list of: |
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References: |
Cushman,J.A. (1925): Some new foraminfera from the Velasco Shale of Mexico . Contributions from the Cushman Foundation for Foraminiferal Research Vol. 1 p. 18-23
White,M.P. (1928): Some index foraminifera of the Tampico embayment of Mexico, Part 2 . Journal of Paleontology Vol. 2(4) p. 280-313
Bolli,H.M. (1957): The genera Globigerina and Globorotalia in the Paleocene-Lower Eocene Lizard Springs Formation of Trinidad, B.W.I . Bulletin of the U.S. National Museum Vol. 215 p. 61-82
Toumarkine,M. and Luterbacher,H.P. (1985): Paleocene and Eocene Planktic Foraminifera. In: Plankton Stratigraphy p. 87-154
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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