THE KAIPAROWITS PLATEAU OF GRAND STAIRCASE-ESCALANTE NATIONAL MONUMENT: A NEW AND CRITICAL WINDOW INTO THE WORLD OF DINOSAURS

In 2001, the Utah Museum of Natural History (UMNH) of the University of Utah established a collaborative agreement with Grand Staircase-Escalante National Monument, initiating the Kaiparowits Basin Project. The primary goals of this multidisciplinary effort have been to survey and collect remains of dinosaurs and other vertebrates from the Upper Cretaceous Wahweap and Kaiparowits formations. The ultimate objective is to reconstruct the changing nature of these Late Cretaceous ecosystems and place them into context with other coeval ecosystems in the Western Interior Basin (WIB). To date, UMNH teams have logged over 16.000 person hours in the field, and surveyed more than 20,000 acres. Within this area, we have identified more than 350 vertebrate localities, 10 of which have been subject to extensive excavation.

Results to date have been abundant and spectacular. Dinosaur discoveries include associated and articulated remains of multiple dinosaur taxa, including tyrannosaurid and maniraptoran theropods, lambeosaurine and hadrosaurine hadrosaurs, as well as chasmosaurine and centrosaurine ceratopsids. Other, less complete, yet significant dinosaur remains include associated hypsilophodont, ankylosaur, and ornithomimid specimens, as well as isolated pachycephalosaur elements. Most of these dinosaur taxa appear to represent species that are new to science and a number of specimens exhibit remarkable preservation, including fossilized skin impressions. Nondinosaurian vertebrates are also diverse, encompassing numerous species of fishes, amphibians, turtles, lizards, crocodiles, and mammals.

Since its inception, this project has sought to place newly discovered vertebrate fossils into a well constrained geologic and paleoenvironmental context; thus, geologic and paleoecological inventory has paralleled the paleontological work, providing key insights into these Late Cretaceous paleoenvironments. Highly significant is the discovery of multiple volcanic ash horizons which can be used for radiometric dating. Dates from the Kaiparowits formation indicate that this unit was deposited over a two million year period, between 76 and 74 Ma, enabling faunal comparisons with several closely contemporaneous, dinosaur-rich formations to the north and south within the WIB.