One day, Dad isn't his usual self. "I guess he's having a dinosaur day," says Mom. To Mikey's surprise, dinosaur dads don't go to work, don't take baths, and don't know how to read. But they do go to school with their kids and eat pizza for dinner, and they love to have stories read to them. The day is a blast. But when it's all over, Mikey wants his old dad back!