CRETACEOUS VERTEBRATES OF THE GRAND STAIRCASE-ESCALANTE NATIONAL MONUMENT

Jeffrey G. Eaton, Department of Geological Sciences
Weber State University, Ogden, UT 84408-2507
jeaton@weber.edu

During the past fifteen years workers at several institutions (University of Colorado, Museum of Northern Arizona, Oklahoma Museum of Natural History, Utah Museum of Natural History, University of California at Berkeley, and Weber State University) have been conducting paleontological research on the more than 2 vertical kilometers of Cretaceous rocks within the Grand Staircase-Escalante National Monument. This research has generated the most comprehensive record of nonmarine vertebrate evolution known in our hemisphere, and possibly the world, over a 22 million year interval in the Late Cretaceous, between about 93 and 71 million years ago.

The Cretaceous rocks have yielded a detailed record of the evolution of fishes, amphibians, lizards, crocodiles, turtles, dinosaurs and mammals as well as excellent, but as yet not as well-studied, records of plants and freshwater mollusks. Important discoveries have been made from all formations and include (from oldest to youngest): the first diverse marsupial fauna in the world and the diversification of vertebrates after the rapid radiation of angiosperm plants (Dakota Formation, Cenomanian stage); the record of a significant extinction event among freshwater fishes and turtles probably resulting from expansion of the Cretaceous epeiric sea into the area and the appearance of the typical members of the Late Cretaceous fauna (Smoky Hollow Member of the Straight Cliffs Formation, Turonian stage); a unique record of near shore and brackish water vertebrates (John Henry Member of the Straight Cliffs Formation, Coniacian-Santonian stages); and the appearance and diversification of placental mammals on our continent along with the diversification of many other kinds of vertebrates (Wahweap and Kaiparowits formations, Campanian stage). This thick sequence has produced dozens of new vertebrate taxa, and in particular, mammalian taxa.

This research undoubtedly represents only the beginning of the kind of research that will be undertaken in the future and was accomplished with specific goals and careful research designs. Paleontological research does not consist merely of the collection of objects, but it is designed to resolve particular problems that are appropriate at the time the research is undertaken. This kind of research cannot be mandated and is inherently distinct from land management and administrative processes. The management policies of the new monument should be designed to promote the preservation of the remarkable resources of the area for future generations of scientists and encourage, but not dictate, scientific research in the region. This was well accomplished in the past under the management of the Bureau of Land Management.

References

Cifelli, R.L., 1990a, "Cretaceous Mammals of Southern Utah, I. Marsupials from the Kaiparowits Formation (Judithian)", Journal of Vertebrate Paleontology, 10:295-319.

Cifelli, R.L., 1990b, "Cretaceous Mammals of Southern Utah, II. Marsupials and Marsupial-like Mammals from the Wahweap Formation (early Campanian)", Journal of Vertebrate Paleontology, 10:320-331.

Cifelli, R.L., 1990c,
"Cretaceous Mammals of Southern Utah. III. Therian Mammals from the Turonian (early Late Cretaceous)", Journal of Vertebrate Paleontology, 10:332-345.

Cifelli, R.L., 1990d, "Cretaceous Mammals of Southern Utah. IV. Eutherian Mammals from the Wahweap (Aquilan) and Kaiparowits (Judithian) Formations", Journal of Vertebrate Paleontology, 10:346-360.

Eaton, J.G., 1991, "Biostratigraphic Framework for Upper Cretaceous Rocks of the Kaiparowits Plateau", in Nations, Stratigraphy, Depositional Environments, and Sedimentary Tectonics of the Western Margin, Cretaceous Western Interior Seaway, Geological Society of America Special Paper 260, p. 47-63.

Eaton, J.G., 1993, "Therian Mammals of the Cenomanian (Late Cretaceous) Dakota Formation, Southwestern Utah", Journal of Vertebrate Paleontology, 13:105-124.