A Grallator-dominated tracksite from the Chinle Group (Late Triassic), Moab, Utah

摘要

Two roadside localities on the northern fringes of Moab, Grand County, Utah yield previously un-described Upper Triassic vertebrate tracks from the Chinle Group (Rock Point Formation). The first locality, designated the highway 191 site, yields dozens of small theropod dinosaur tracks (Grallator) preserved on a single, fallen slab. The tracks form a monospecific assemblage preserved as natural casts. The assemblage is representative of what has been referred to as Rhaetic assemblage II which is dominated by small Grallator tracks. In situ Grallator tracks are also described from a nearby locality, referred to as the Matrimony Spring site, where they are found in association with the ichnogenus Brachychirotherium. Many other sites with similar, often more-diverse, Late Triassic ichnofaunas are known from the region.