Abstract The Late Campanian-aged Kaiparowits Formation (72.5–76.6 Ma) is a thick, fossiliferous fluvio-overbank–lacustrine complex deposited in south-central Utah. Host to one of the richest, most diverse Campanian terrestrial fossil records in North America, the physical environment of the Kaiparowits ecosystem, particularly the dynamics of the hydrological system, remains obscure. In 2014, an extensive bonebed was found in a conglomeratic sandstone unit of fluvial origin, known as the Rainbows and Unicorns Quarry. Isotopic compositions of serially sampled tooth enamel phosphate (δ 18 O p ) from tyrannosaur teeth were analysed to see if they held data that could clarify the palaeohydrology of the Kaiparowits Formation. To assess a greater palaeoecological context for the tyrannosaurs, the isotopic composition of their teeth was compared to other faunal elements, including the giant alligatoroid Deinosuchus , and turtles (Baenid, Gilmoremys , Neurankylus and Trionychid) from the same quarry. The δ 18 O w calculated from tyrannosaur was low, suggesting that isotopically-light, high-altitude runoff strongly influenced the local hydrology of the Kaiparowtis Formation. The seasonal change in δ 18 O of tyrannosaur drinking water ranged from −21.0 to −14.4‰ V-SMOW, while δ 18 O w calculated from turtles and crocodiles ranged between an average of −9.3 and −10.9‰, respectively. The seasonal precipitation pattern and temperature of the Kaiparowits Formation was then compared to analogue settings, such as the monsoonal climate of Hanoi, Vietnam and Cuiaba, Brazil. While similarities exist between these sites, the unique configuration of the Sevier Mountains adjacent to the nearby Western Interior Seaway provides the unique setting for a complex palaeohydrological system that results in a wide range of δ 18 O w as a result of cold seasonal precipitation at high elevation that runs off and mixes with local precipitation (−6.0 to −4.68‰) sourced from the Western Interior Seaway. This study demonstrates the importance of serial- and micro-sampling of multi-taxa comparisons for isotopic investigations of palaeohydrological systems.

ABSTRACT Today, the United States Department of the Interior manages 500 million acres of surface land, about one-fifth of the land in the United States. Since enactment of the Antiquities Act in 1906, historic and scientific resources collected on public land have remained government property, held in trust for the people of the United States. As a result, the Department of the Interior manages nearly 204 million museum objects. Some of these objects are in federally managed repositories; others are in the repositories of partner institutions. The establishment of the United States as a nation corresponded with the development of paleontology as a science. For example, mastodon fossils discovered at or near present-day Big Bone Lick State Historic Site, Kentucky, found their way to notable scientists both in the United States and in Europe by the mid-eighteenth century and were instrumental in establishing the reality of extinction. Public land policies were often contentious, but generally they encouraged settlement and use, which resulted in the modern pattern of federal public lands. Continued investigation for fossils from public land filled the nation’s early museums, and those fossils became the centerpieces of many museum exhibitions. Case studies of the management of fossils found in Fossil Cycad National Monument, the John Day fossil beds, the Charles M. Russell National Wildlife Refuge and surrounding areas of public land, the American Falls Reservoir, and Grand Staircase–Escalante National Monument are outlined. These examples provide a sense of the scope of fossils on federal public land, highlight how their management can be a challenge, and show that public land is vital for continued scientific collection and research.