Zion National ParkPage 50 of 62
Twenty Years of Fossil Surveys in Utah's National Parks
For 20 years, paleontologists of the Utah Geological Survey (UGS) have worked with the National Park Service (NPS) to inventory and monitor fossils in Utah's national parks, and they have documented hundreds of new fossil localities. This account was written by Donald DeBlieux and James Kirkland of the UGS and Vincent L. Santucci of the NPS Paleontology Program; this version is rewritten in hubnx's own words, with their figures left out. They call the partnership remarkably successful, and say the results help park staff manage fossils, improve visitor experiences and reconstruct past life.
Why Utah
Utah has one of the best fossil records anywhere. Fossils in its parks range in age from the Paleozoic through the Holocene, but most are in the Mesozoic rocks that form the red rock scenery of the Colorado Plateau, particularly Triassic and Jurassic rocks. The Triassic and the Triassic–Jurassic transition matter because that interval is linked to a major evolutionary radiation and an extinction event tied to the rise of most modern land animal groups. The Triassic Chinle Formation is one of the most fossil-rich formations on the plateau, and much of what is known about Late Triassic land ecosystems comes from it, so the surveys concentrated there. Jurassic sandstones rarely preserve body fossils and are more likely to preserve tracks.
Park by park
| Park unit | What the surveys found |
|---|---|
| Arches | Dinosaur-bearing Mesozoic strata, including the Morrison Formation and the Early Cretaceous Cedar Mountain Formation. A Cedar Mountain tracksite has several kinds of dinosaur footprints, including that of a dromaeosaur probably related to Deinonychus, and traces the authors think were made by a bird- or pterosaur-like animal floating in shallow water and probing the bottom with its beak. Part of a dinosaur skeleton in the Kayenta Formation was the first dinosaur body fossil found in the Kayenta in Utah; it is under study and thought to belong to a theropod similar to Dilophosaurus |
| Zion | Chinle Formation sites with phytosaurs, aetosaurs and fish. The trail once called the Petrified Forest Trail was renamed the Chinle Trail to reduce vandalism and theft of fossil wood. A specialist from the University of Houston identified the colorful rocks above the Shinarump Member as the Cameron Member rather than the Petrified Forest Member. Dozens of dinosaur tracksites in the Moenave and Kayenta Formations, with a megatrack surface at the top of the Springdale Sandstone Member. The park received maps of fossil-yield potential to help manage sensitive areas |
| Glen Canyon National Recreation Area | Surveyed by boat along Lake Powell; many wood and bone sites in the Chinle and many tracksites in the Kayenta; 50 new localities. As lake levels drop, the sites are more threatened by erosion and vandalism. Monitoring sites with crack monitors measure movement in track surfaces to estimate erosion rates |
| Capitol Reef | Some of the most fossil-rich Chinle outcrops the team found, in the Monitor Butte Member and Capitol Reef Bed; dozens of new localities. The rocks record climate change as the supercontinent Pangea drifted from the humid tropics into the arid subtropics in the Late Triassic. A 1980s site with a standing “grove” of giant horsetail (Equisetites) was rediscovered and modeled in 3D to judge its vulnerability to erosion. Rocks mapped as Jurassic Morrison Formation in the north of the park turned out to be Cretaceous Cedar Mountain Formation, and the geologic map is being updated |
| Canyonlands | Began in fall 2020 in the Island in the Sky District, reached on the White Rim Trail. The database held two localities there; two 10-day expeditions found more than 70 new sites, with phytosaur, aetosaur and fish bones and petrified wood in the Chinle. In the Early Triassic Moenkopi Formation they found scientifically significant tracksites in the Torrey Member, mostly “swim tracks” of floating reptiles paddling along the bottom, which a swim-track expert from UC Davis called among the best preserved on the Colorado Plateau |
What next
The authors plan to continue in the Moenkopi and Chinle Formations at Canyonlands and to explore Paleozoic rocks that could yield significant vertebrate fossils. They want the partnership to go on so that these resources are managed for the benefit of the American people and visitors.
Sources
- Donald DeBlieux and James Kirkland (Utah Geological Survey) and Vincent L. Santucci (National Park Service Paleontology Program), A 20-year Partnership between the Utah Geological Survey and the National Park Service to Inventory and Monitor Fossil Resources in Utah's National Parks, Park Paleontology News, National Park Service (the imported title was cut off; completed from the page's address); rewritten in hubnx's own words. The authors' figures are not reproduced.