ABSTRACT
Fossil footprints and fossil bones provide different sorts of information about the animals that left them in the rock record. Footprints also provide some level of taxonomic identification because dinosaurs with differently constructed feet left behind characteristic footprints. Traditionally, paleontologists have modeled track formation as the result of an animal walking on a layer of wet unconsolidated mud or sand that is competent, or stiff enough to hold the shape of the print without falling apart. The dried layer preserves the footprint and is more resistant to erosion than unconsolidated mud so when the next immersion under water occurs and sediment is deposited, the track is preserved and infilled by burial from a new layer of mud or sand. The Lower Cantwell Formation contains the only track evidence in northern North America of therizinosaurs, another type of theropod dinosaur. Therizinosaurs are highly unusual theropods in that may have been herbivorous, which is unusual for non-avian theropods.
