Microfósiles (Foraminifera, Ostracoda) y su respuesta a las variaciones paleoambientales: Un ejemplo en la Formación Allen (Cretácico Superior), Cuenca Neuquina, Argentina

morphological abnormalities in benthic foraminifer tests and ostracods shells and carapaces from the allen formation (late campanian-early maastrichtian) in northern patagonia, argentina are analized. abnormal tests of protelphidium sp. from the auca mahuevo section (69o00′w-37o30′s) constitute up to 74% of the total specimens. at the section close to pellegrini lake (68o00′w-38o40′s), cophinia alleniensis ballent with phenotypic hollow nodes reach near 30% of the total specimens. the sedimentology of the sections and the character of the accompanying microfauna indicate that the morphological deformities in both taxa were probably caused by hypersalinity and/or fluctuations in salinity, and also by eutrophication during deposition of auca mahuevo section. descriptions and systematic updating of both taxa are included.