Regional Distribution of Some Cretaceous Rotaliporidae and Globotrucanidae (Foraminiferida) within North America
AbstractA comparison of Upper Cretaceous planktonic Foraminifera from the Pacific Coast with those of the Atlantic Coast and Gulf-Caribbean regions provides new information on the stratigraphic and paleographic distribution of Praeglobotruncana, Hedbergella, Globotruncana and Rugoglobigerina. Late Cretaceous planktonic Foraminifera were neither universally nor ubiquitously distributed. Genera ranged widely during the Turonian to early Maestrichtian but some species were restricted geographically. Many early Upper Cretaceous taxa were cosmopolitan but apparently did not extend into high latitudes. On the West Coast endemism within the Coniacian faunas is marked among the Globotruncanidae and less pronounced in the Rotaliporidae. Campanian to early Maestrichtian planktonic faunas in North America contain many cosmopolitan globotruncanids. Late Maestrichtian planktonic index Foraminifera become increasingly restricted to the Tethyan region suggesting a retreat of the tropics. Faunas of this age are not recognized in the Pacific Coast. Planktonic Foraminifera provide an excellent basis for stratigraphic correlations between the Pacific Coast and the Gulf-Caribbean region for strata of Cenomanian Turonian and Campanian-early Maestrichtian age. Thirty-two species of the families Rotaliporidae and Globotruncanidae from California are systematically described and illustrated.