YELLOWSTONE NATIONAL PARK, Wyo. (AP) - A family trip to Wyoming's Yellowstone National Park has turned tragic for a Michigan family. Park officials say a woman lost her footing after stepping over a retaining wall to take a picture and went over a cliff, falling 500 feet to her death in a canyon. The 52-year-old was visiting the park with her husband and two children. A ranger rappelled down the canyon wall to reach the woman, but she was dead at the scene.