Abstract

Nonmammalian vertebrate fossils are common in Late Cretaceous rocks throughout Wyoming. Strata of this age, spanning 35 million years (65-100 million years ago) and reaching thicknesses of 3,000 meters, flank many of the major structural basins within the state. Comprehensive faunal lists are compiled for the Late Cretaceous of Wyoming. The faunas of the nonmarine Lance and "Mesaverde" formations are the most diverse and significant within the state. Late Cretaceous non-mammalian vertebrate fossils found in Wyoming consist of remains of sharks, rays, bony fishes, frogs, salamanders, champsosaurs, turtles, lizards, mosasaurs, snakes, alligators, crocodiles, pterosaurs, dinosaurs, plesiosaurs, ichthyosaurs, and birds. These organisms inhabitated the marine, transitional marine, or nonmarine coastal floodlain and upland environments associated with a subtropical to warm temperate, fluctuating Late Cretaceous epicontinental seaway. Although Late Cretaceous vertebrate fossils have been known in the state since 1872, few previous published faunal lists exist. Current research on faunas of this age from Wyoming will add greatly to the understanding of the biota of this part of the Western Interior during the end of the Mesozoic.