A MENAGERIE OF MOSASAURS FROM THE PFISTER RANCH EXPOSURE OF THE PIERRE SHALE

Located in Eastern Wyoming, the Pfister Ranch Exposure is a roughly 410-meter-long escarpment of the Sharon Springs Member of the Pierre Shale. The Glenrock Paleon Museum conducted fossil excavations at the Pfister Ranch Exposure from 1998 to 2003 and, in collaboration with the College of Charleston, from 2020-2023. Cranial and jaw material from more than a half-dozen mosasaurs was recovered. All these specimens are referable to the subfamily Plioplatecarpinae. Four of the specimens can tentatively be ascribed to the genus Platecarpus based on a striated tooth structure and the presence of twelve alveoli in each gracile dentary. One skull has characteristics consistent with the rarer genus Latoplatecarpus with twelve fluted teeth in the maxilla.