The occurrence of hinge reversal in Buntonia beninensis Reyment (Ostracoda), Paleocene, Nigeria

Abstract

A microfossil study of two boreholes, Araromi and Gbekebo (Geological Survey of Nigeria borehole numbers 1131 and 1132) (Figure 1), revealed the occurrence of Buntonia beninensis Reyment (1960, 1963) in the late Paleocene interval. This species was found to have forms with normal overlap and hinge element and forms with a reversal of these morphological features. In the former, the left valve is larger than the right, which bears the projecting terminal hinge element, whereas, in the latter, the larger valve is the right valve with the smaller left valve bearing the projecting terminal hinge element.