A time scale for Paleocene rocks of the Rocky Mountain region has been constructed from provincial palynomorph biozones and vertebrate ages compared to worldwide planktonic foram ages and K-Ar boundary age estimates. As presently interpreted, the major elements of this time scale, from older to younger, are as follows. (a) Top of Cretaceous Maestrichtian foram age = top of Triceratops dinosaur age = top of concurrent-range zone of palynomorphs Proteacidites, most Aquila-pollenites, Cranwellia, Balmeisporites, and several others: about 65 m.y. (b) Early Paleocene, early Danian foram age = Puercan and earliest Torrejonian mammal ages = assemblage zone of palynomorphs Momipites coryloides and Ulmoidipites tricostatus: about 65 to 62 m.y. (c) Early Paleocene, late Danian fora age = early and middle Torrejonian mammal age = concurrent-range zone of palynomorphs Maceopolipollenites leboensis and M. amplus: about 62 to 60 m.y. (d) Late Paleocene, early Thanetian foram age = late Torrejonian and early Tiffanian mammal ages = concurrent-range zone of palynomorphs Maceopolipollenites amplus and Tiliaepollenites sp.: about 60 to 57.5 m.y. (e) Late Paleocene, late Thanetian foram age = late Tiffanian and Clarkforkian mammal ages = assemblage zone of palynomorphs Pistillipollenites and Caryapollenites: about 57.5 to 53.5 m.y. (f) Base of Eocene Y presian foram age = base of Wasatchian mammal age = base of concurrent-range zone of palynomorphs Platycarya, Tilia, and Eucommia: about 53.5 m.y.

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