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Abstract
The Jurassic Gypsum Spring and Sundance Formations of the Bighorn Basin host several vertebrate trackways. Sequence-stratigraphic studies indicate several other potential trackway
horizons in coastal facies. In June–July 2021, I tested for the presence of new trackways in these
units. I discovered 5 trackways containing 318 vertebrate tracks along horizons hypothesized to
harbor tracks. Two trackways with 149 tracks from swimming reptiles were found in the
Gypsum Spring Formation. Three trackways with 169 tridactyl prints were discovered in the
Canyon Springs Formation near the Red Gulch Dinosaur Tracksite (RGDT). One unidentified
track was observed in the Windy Hill Sandstone at Sykes Mountain. Considering the distance
searched, I expected to find more trackways. New tracks appear to have been made by
vertebrates previously known from the Gypsum Spring and Sundance Formations. Given the
diversity of the overlying Morrison Formation, it is surprising that a greater trackway diversity
was not found.