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 ). |
Howe,H.V. (1939):
Louisiana Cook Mountain Eocene Foraminifera. Louisiana Dep. Cons. . Geol. Surv. Bull. Vol. 14 p. 1-122
Bandy,O.L. (1949):
Eocene and Oligocene foraminifera from Little Stave Creek, Clarke County, Alabama . Bulletins of American paleontology Vol. 32 p. 1-211
Jenkins,D.G. (1978):
Guembelitria samwelli Jenkins, a new species from the Oligocene of the Southern Hemisphere . J. foramin. Res. Vol. 8 p. 132-137
Kroon,D. and Nederbragt,A.J. (1990):
Ecology and Paleoecology of Triserial Planktic Foraminifera . Marine Micropaleontology Vol. 16 p. 25-38
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
|
Taxon Concept provided by
