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Origin and Evolution of the Foraminiferal Genus Orbulina d'Orbigny

W. H. Blow
Micropaleontology
Vol. 2, No. 1 (Jan., 1956), pp. 57-70
DOI: 10.2307/1484492
Stable URL: http://www.jstor.org/stable/1484492
Page Count: 14
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Origin and Evolution of the Foraminiferal Genus Orbulina d'Orbigny
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Abstract

This paper traces in detail the evolution of the genus Orbulina d'Orbigny from a species of Globigerinoides similar to Globigerinoides triloba. Two independent lines of evolution are discussed, the first leading to Orbulina universa, and the second to "Orbulina" bilobata. The latter species is removed to a new genus, Biorbulina, and two new species of Globigerinoides are proposed. The stratigraphic range of Orbulina in Trinidad and in Falcón, Venezuela, is discussed, and a preliminary correlation of the Oligo-Miocene sediments of the two areas is given.

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