Rudist bivalve assemblages from the Back Rio Grande Formation (Cretaceous: Campanian) of Jamaica and their stratigraphic significance

The lithostratigraphy of the Back Rio Grande Formation (Campanian) in the Blue Mountains of eastern Jamaica is described. Six informal members are recognised; three limestone and three volcaniclastic units. The rudist assemblages from the three limestone members are described, and the occurrence of larger foraminifers is discussed. The lower limestone member yields Barrettia monilifera Woodward, Durania krijneni sp. nov., Chiapasella cubensis Rutten, Bournonia thiadensi Vermunt, Branislavia stellaplicatus sp. nov. and Antillosarcolites? cf. macgillavryi Chubb together with several forms left in open nomenclature as well as the larger foraminifer Pseudorbitoides trechmanni Douvillé. The middle limestone member yields D. krijneni sp. nov. and C. cubensis. In the upper limestone member occur Barrettia sp. A, D. krijneni sp. nov., C. cubensis, Titanosarcolites sp. A and A.? cf. macgillavryi Chubb together with larger foraminifers including Pseudorbitoides and Vaughanina cubensis Palmer. The lower limestone member is placed in the middle Campanian, and the upper limestone member together with the overlying Rio Grande Formation are assigned a late Campanian age on the basis of their rudist and larger foraminifer assemblages. Chiapasella cubensis is recognised as a good marker for both the middle and upper Campanian.