CARMELOPODUS AND THE SUNDANCE VERTEBRATE ICHNOFAUNAL PROVINCE: INSIGHTS INTO THE PRESERVATIONAL COMPLEXITIES OF VERTEBRATE ICHNOTAXA

Wyoming's Bighorn Basin contains the most extensive dinosaur track localities in the state and the most thoroughly documented dinosaur tracksites in the world (e.g., Red Gulch Dinosaur Tracksite). Vertebrate ichnology research has focused primarily, on the tridactyl pes impressions of hundreds (and perhaps thousands) of small- to medium-sized, Middle Jurassic carnivorous dinosaurs. These tracks are located on a preserved tidal flat facies of the Lower Sundance Formation in a geographically restricted area of northern Wyoming (i.e., Sundance Vertebrate Ichnofaunal Province). Exhaustive, state-of-the-art studies of the track morphotypes, illustrate a unique multilayered preservation of the footprints. Although, the unique Carmelopodus digital pattern (i.e., 2-3-3) is represented by most of the tracks, morphological differences related to variations in substrate consistency, sedimentary/ biogenic structures, and trackmaker (e.g., size and type) suggests a new ichnospecies should be recognized. Careful analysis of thousands of these tracks (along with current work on the footprints of modern flightless birds) allows us to understand the formation of these footprints on a water-saturated, thixotropic shore; and highlights apparent biases in documentation and interpretation in footprint studies. As a result, the research on a statistically valid data set (i.e., over 35,000 track attributes representing over 1500 footprints) of a single ichnotaxa provides us with evidence for our interpretations about the community dynamics of a population of gregarious dinosaurs (ranging in age from yearling to adult), and illustrates the importance and value of having a large and consistently documented set of data to guard against the trap of "prehistoric hyperbole."