Fossil Cycad National Monument in northwestern Fall River County, South Dakota, preserved a remarkable concentration of fossils from the cycad-like plant Cycadeoidea, now identified as bennettitaleans, in the Dakota Sandstone Formation. Discovered in 1892, the site drew early scientific attention but also suffered heavy disturbance as local diggers and later researchers removed specimens. George Reber Wieland helped secure federal protection, and the monument was established in 1922, covering 320 acres near the Black Hills. Yet weak oversight, erosion, theft, and continued excavation stripped the site of visible fossils, and its monument status ended in 1957. Surviving specimens remain in major museum and university collections.