LATE CRETACEOUS ICHNOLOGICAL EVIDENCE FROM THE KAIPAROWITS FORMATION OF THE GRAND STAIRCASE NATIONAL MONUMENT, UTAH: IMPLICATIONS AND SIGNIFICANCE OF A CONTINENTAL NON-MARINE ENVIRONMENT

Although the basic concepts of the Kaiparowits Formation sedimentation are generally well understood in the Kaiparowits Basin section of the Grand Staircase National Monument (GSNM), the specific details of the accompanying vertebrate, invertebrate and plant ichnology are not. Many recent studies of GSNM depositional systems emphasize the physical sedimentology and vertebrate paleontology. Measured sections typically depict sedimentary structures, textures, grain size, body fossils, microfossils, geochemical analyses, and age dating. Although most descriptions note that burrows, tracks, coprolites, log and leaf impressions are present, a detailed analysis of the ichnology is a work in progress. Assessment of the bioturbation density’s and distributions, identification of ichnospecies and ichnogenera, and general information on the diversity, abundance, and ethological groupings of the trace fossil suites are almost totally lacking. Consequently, by incorporating ichnological evidence and their unique characteristics of those ichnological suites, may be critical in identifying various subenvironments in these continental deposits.

The environment animal sediment interactions are well documented from marine sediments and very little is known from non-marine rocks. The excellent exposures of the Kaiparowits Formation at GSNM provide us with an opportunity to combine ichnological data, sedimentological data, and body fossil assemblages, to better understand the depositional environments. Environmental factors such as energy conditions, substrate consistencies, depositional rates, salinity, physicochemical and biochemical conditions, and oxygenation, all lead to discrete biological communities. These faunal and floral communities yield recurring, strongly facies-controlled groupings of vertebrate, invertebrate, and plant trace fossils that reflect specific combinations of organism behaviors (ethology), preservational and environmental factors. Such recurring groupings have been designated “ichnofacies”. The Kaiparowits Formation continental rocks provide us with an unprecedented opportunity to incorporate non-marine ichnology, body fossil assemblages, geology, and ecology, of terrestrial animals and plants during the Late Cretaceous.