REVIEW OF CRETACEOUS MAMMALIAN PALEONTOLOGY: GRAND STAIRCASE-ESCALANTE NATIONAL MONUMENT, UTAH

The Cretaceous section on the within the Grand Staircase-Escalante National Monument spans at least 20 million years (current isotopic dates provide a range of 94.7-73.9 Ma) and includes nonmarine faunas from the Cenomanian through Campanian. Seven genera of mammals (the multituberculates Cimolodon, Paracimexomys, Dakotamys, the therian Dakotadens, the marsupials, Pariadens, Alphadon, Protalphadon) are known from the Dakota Formation (Cenomanian); 8 genera (the multituberculates Paracimexomys, Bryceomys, the cladotherians Spalacotheridium, Symmetrodontoides, the marsupials Dakotadens, Alphadon, Protalphadon, Anchistodelphys) from the Smoky Hollow Member of the Straight Cliffs Formation (Turonian); 9 genera (the multituberculates Mesodma, ?Cimolomys, Cimolodon, Cedaromys, the cladotherians Spalacotheridium, Potamotelses, Picopsis, the marsupials Alphadon, Varalphadon) from the John Henry Member (Santonian) of the Straight Cliffs Formation; 15 genera (the multituberculates Mesodma, Cimolodon, Meniscoessus, Cimolomys, Cimexomys, Bryceomys, Cedaromys, ?Paracimexomys, the cladotherians Zygiocuspis, Symmetrodontoides, the marsupials Varalphadon, Alphadon, Iugomortiferum, Anchistodelphys, the placental insectivore Paranyctoides) from the Wahweap Formation (lower Campanian – Aquilan); and 16 genera (the multituberculates Mesodma, Cimolodon, Kaiparomys, Meniscoessus, Cimolomys, Cimexomys, Cedaromys, Dakotamys, the marsupials Aenigmadelphys, Varalphadon, Turgidodon, Alphadon, the ungulatomorph Avitotherium, the placental insectivores Gypsonictops, Cimolestes, Paranyctoides) from the Kaiparowits Formation (upper Campanian – Judithian). At the genus level, the mammalian fauna includes 23 first occurrences, 12 last occurrences, and 6 unique occurrences. The Cretaceous sequence present within the Grand Staircase-Escalante National Monuments provides a unique and remarkable record of vertebrate evolution. Although we have been undertaking research in the region for more than 20 years, our understanding of the true diversity and stratigraphic ranges of mammalian taxa is still in its infancy.