| Description |
The Nugget Sandstone is a Triassic/Jurassic eolianite in western North America. It represents a portion of one of the largest dune environments to have ever existed in the geologic record. Paleontological interest in the Nugget Sandstone has grown in recent years upon numerous discoveries of vertebrate and invertebrate body fossils, trace fossils, and plant fossils. Invertebrate trace fossils in the Nugget Sandstone near Vernal, Utah, are identified, described and highlighted in this study, with an overview of past fossil discoveries in the Nugget and Navajo sandstones. Invertebrate trace fossils in this area include Entradichnus meniscus, Entradichnus isp., Planolites beverleyensis, Taenidium isp. "A," Taenidium isp. "B," Skolithos and Planolites isp., ‘burrow clusters', ‘large oblique burrows', ‘flared burrows', Paleohelcura, and Octopodichnus. Arthropods, such as insects and arachnids, are considered possible trace makers. Vertebrate trace fossils of this same area include Brasilichnium, Grallator, Eubrontes, Brachychirotherium, Pseudotetrasauropus, Tetrasauropus, and Otozoum. Possible sphenophytes, cycads, and algal build-ups comprise the evidence for primary production in the ecosystem. Sediment moisture must have played a key role in the production and preservation of all trace fossils in the Nugget Sandstone. Because of this, these trace fossils indicate that moisture was important for supporting such complex ecosystems, and that extended wet climatic intervals must have persisted intermittently between arid intervals. With fossil evidence for primary production, herbivorous insects, and carnivorous arachnids provided in this thesis, as well as indirect evidence for environmental moisture content during deposition of the Nugget Sandstone, a more complete picture of the paleoecology of this ancient sea of sand can be constructed. |
