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Rosalina (genus)
''Rosalina'' is a genus of foraminifera included in the Rotaliida, rotaliid family Rosalinidae. ''Rosalina'' has a smooth plano-convex to concavo-convex trochospiral test in which the chambers are rapidly enlarging and all visible on the convex spiral side and subtriangular and strongly overlapping on the umbilical side, the final chamber taking up about one-third of the circumference. Sutures on the spiral side are depressed and oblique, curving back at the periphery. The umbilicus is open, partly covered by triangular umbilical flaps extending from each chamber of the final whorl. Chamber interiors are simple and undivided with subacute peripheries. Walls are calcareous, with an organic inner lining, and are distinctly perforate. The aperture is a low interiomarginal arch near the periphery on the umbilical side, with narrow bordering lip. ''Rosalina'' has a stratigraphic range from the Eocene to recent and a cosmopolitan distribution. Related genera include ''Neoconorbina' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope Carbon-13, 13C in the atmosphere was exceptionally low in comparison with the more common isotope Carbon-12, 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Popigai impact structure, Siberia and in what is now ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
