Over the course of 75 million years, the area now known as Badlands National Park was home to seven types of animals whose lineages met different fates as climate and habitats changed. Some adapted to new environments, including early horses and dogs, which were flexible enough to survive and belong to lineages that evolved into modern horses and dogs. Some moved to more favorable habitats, as members of the alligator family once lived across North America, including here, before cooling and drying conditions shrank their range to places like Florida. Some could not adapt to changing climates and habitats, and four of the groups represented here, including the oreodont, went extinct.