Original paper
On the extinction of costate buliminas in the Egyptian Eocene rocks
Hussein, Aly I. M.
published: 1/1/1997
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ArtNo.: ESP026003503004
Abstract
The costate buliminas in the Egyptian Eocene rocks are represented by Bulimina jacksonensis CUSHMAN and its earliest known occurrence is in the latest Early Eocene. After a period of rapid expansion during the Middle Eocene, it became extinct by the end of that time or at the earliest time of the Late Eocene. The sudden mass reduction of the costate buliminas is nearly at the same stratigraphic horizon allover Egypt and is of regional rather than local significance. That stratigraphic horizon could be used as a marker for the Middle Eocene/Upper Eocene boundary. It seems that the rapid shallowing of the sea during that time to less than middle neritic depths and the associated modification in temperature were the main factors responsible for its extinction.