Modern Foraminifera collected along three traverses across the Gulf of Mexico show that morphologic variations within species (clines) may serve as excellent indicators of bathymetry. Many species of Foraminifera are known to have restricted upper depth limits that can be used in making paleobathymetric interpretations. Penetration of Neogene offshore sediments of the Gulf of Mexico allows paleontologists to interpret paleobathymetry of sediment samples with a higher degree of accuracy through comparison of the ancient faunas with these modern counterparts.

Some depth-related morphologic variations of species, such as size, form, and ornamentation, are known to have importance in paleobathymetric interpretations and are useful in evaluation of an assemblage. The more obvious and important depth-related morphologic variations have been recorded for the genera Uvigerina, Laticarinina, Gyroidina, and Hoglundina. Genera which include especially significant depth-indicator species include Gyroidina, Cibicides, Eponides, Oridorsalis, Cyclammina, Bulimina, Osangularia, and Alabamina.

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