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Species "Globorotalia" nana Bolli 1957 | ||||||
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| Diagnosis / Definition: | ||||||
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Kennett & Srinivasan (1983): Test small, very low trochospiral, tightly coiled, equatorial periphery quadrilobate, axial periphery rounded; chambers four to four and a half in the final whorl, increasing rapidly in size as added; sutures on both spiral and umbilical sides radial and depressed; surface distinctly cancellate with subhexagonal pits; umbilicus narrow; aperture interiomarginal, extraumbilical-umbilical, a low arch bordered by a thick rim. |
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| Discussion / Comments: | ||||||
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Kennett & Srinivasan (1983): "Gr." nana is distinguished from Gr. (Globoconella) incognita by having a low aperture and from Gr. (Jenkinsella) opima by being smaller and more tightly coiled, with four to four and a half chambers in the final whorl. "Gr." nana seems to be a central, ancestral globorotalid stock from which several Neogene lineages radiated close to the Oligocene-Miocene boundary. In temperate areas, "Gr." nana seems to have evolved in the early Miocene to Gr. (Globoconella) incognita, the earliest member of the Globoconella lineage, by developing a high-arched aperture. |
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| Synonym list: | ||||||
| Kennett & Srinivasan (1983): 1957 Globorotalia opima nana Bolli. - Bolli : p.118 pl 28 figs 3 a-c
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| References: | ||||||
Bolli,H.M. (1957): Kennett,J. and Srinivasan,M.S. (1983): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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