ICHNOFOSSILS OF THE CEDAR MOUNTAIN FORMATION (NORTHEASTERN UTAH) AND THEIR PALEOENVIRONMENTAL IMPLICATIONS

The Cedar Mountain Formation (Cretaceous, Albian) within Dinosaur National Monument (northeastern Utah) has garnered recent interest with the discovery of new vertebrate fossils. The close scrutiny of the vertebrates requires a thorough evaluation of the climate recorded by the formation. However, vertebrate fossils alone are poor indicators of paleoenvironmental conditions and detailed stratigraphic and sedimentologic studies cannot reveal every detail. Ichnofossils supply a more thorough description of local climatic, ecologic, and environmental conditions.

Ichnofossils were discovered in three sediment facies within the Ruby Ranch Member of the Cedar Mountain Formation. Facies 1 is the basal carbonate unit. Lateral growth forms indicate that the unit remained near the surface during a period of stability. Additionally, the unit was likely lithified before plant roots reached it. Facies 2 consists of discontinuous carbonate units representing evaporative lakes. These units preserve a combination of rhizolith and arthropod burrows. Facies 3, deposited by sandy fluvial channels, contains primarily arthropod burrows and lateral trails.

This poster describes the morphology and considers the environmental implications of the ichnofossils of each unit and the Cedar Mountain Formation within Dinosaur National Monument. This study supports previous environmental analyses indicating an arid environment interuptted by flashy, intense precipitation events.