The Musselshell Creek flora in Idaho from 12.0-10.5 million years ago helps us understand the climate and environment of the Pacific Northwest during the late Middle Miocene. Fossils of plants like dicotyledons and conifers were found in lake sediments, along with well-preserved leaves, pollen, and spores. The flora suggests a warm to cool temperate climate similar to the modern Mid-Atlantic coast of the United States. Notable plant genera include Quercus, Taxodium, and Ginkgo, with pollen from Pinus and Abies. The fossils indicate a streambank to floodplain environment in the region during that time period.