Statistic biostratigraphy and paleoecology of tropical Upper Cretaceous dinoflagellate cysts

Abstract

The statistical and probabilistic analyses of a database of Upper Cretaceous tropical dinoflagellate cysts from Venezuela allow us to recognize 21 species in the optimal stratigraphic sequence. Compilation of the dinoflagellate cysts reported in ten studies of Upper Cretaceous tropical localities from northern South America and the Gulf of Guinea allow the recognition of a rich assemblage (262 species), dominated by gonyaulacoid (129 spp), followed by protoperidinioid (82 spp), areoligeroid (29 spp), gymnodinioid (12 spp) and ceratioid (10 spp) taxa. Seventy-three species in the tropical database are reported in both regions, allowing the age calibration of the optimal sequence from Venezuela. The proposed final sequence of bioevents allows recognition of most stages in tropical Upper Cretaceous strata. The high diversity of the Spiniferites-Achomosphaera group and scarcity of Impagidinium indicates shallow marine depositional environments for most of the Upper Cretaceous tropical localities included.The dominance of gonyaulacoid species in the tropical database suggests that these were the dominant primary producers in the tropical Late Cretaceous oceans.