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Species Guembelitria columbiana Howe 1939 | ||||||
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Discussion / Comments: | ||||||
Van Eijden & Smit (1991): Remarks. G. columbiana occurs in the <125-ìm fraction of several Eocene samples. Usually it is rare and extremely small. It is most common at Site 753, where it occurs throughout the middle Eocene. Usually, it is found in the mid-middle Eocene (Kroon and Nederbragt, in press). This species can be so extremely small that it will pass through the commonly used 63-ìm sieves. Kroon & Nederbragt (1990): The wall is covered with pustules, which are concentrated on the chambers of the last few whorls. The aperture is asymmetric and is bordered by a lip with a toothplate. G. stavensis should have a more gently flaring test than G. columbiana, which difference we regard as intraspecific variation. The grainy wall structure and secondary apertures of G. samweUi Jenkins appear to be the result of partial dissolution and/or recrystallization of the test, which is the same as that of some G. cretacea specimens from the E1 Kef section (Plate II, 6, 10). The presence of a toothplate in G. columbiana is deduced from the asymmetric aperture that shows one side curving inward into the interior of the test (Plate II, 10). Guembelitria columbiana has been described from Middle Eocene to Upper Oligocene sediments in the United States, Australia and New Zealand. We found it in sample HK408 from the middle Eocene P 14 Zone of the Navet Formation, Trinidad; as well as in Middle Eocene samples 75-10 and 75-11, from Grand Banks core hole 23 (Fig. 1 ). |
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Systematics: | ||||||
29 Genus Guembelitria Species Guembelitria columbiana |
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Synonym list: | ||||||
Van Eijden & Smit (1991): 1939 Guembelitria columbiana Howe. - Howe : p.62 pl. 8, figs. 12-13
1991 Guembelitria columbiana Howe. - Van Eijden & Smit : p.120 pl. 2, fig. 6
Kroon & Nederbragt (1990): 1939 Guembelitria columbiana Howe. - Howe : p.62 pl. 8; figs. 12, 13
1949 Guembelitria stavensis Bandy. - Bandy : p.124 pl. 24; fig. 5
1978 Guembelitria samwelli Jenkins. - Jenkins : 132-134 pl. 1; figs. 1-9
1990 Guembelitria columbiana Howe. - Kroon & Nederbragt : p.34 pl. 2; figs. 1-3; 9
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Was used in synonym list of: | ||||||
References: | ||||||
Howe,H.V. (1939): Bandy,O.L. (1949): Jenkins,D.G. (1978): Kroon,D. and Nederbragt,A.J. (1990): Van Eijden,A.J.M. and Smit,J. (1991): |
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Anonymous: Unedited TaxonConcept data | ||||||
This work is licensed under a Creative Commons Attribution 2.5 License. | ||||||
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