WAUSAU, Wisconsin (AP) -- Who is that mysterious, elegant man? And why is he sitting on a dead horse? Such are the questions sparked by a black-and-white photograph taken in Sheboygan, Wisconsin, between 1876 and 1884 that has led to nationwide curiosity, speculation and jokes. It's a picture of a mustachioed man in a suit and top hat who sits rakishly on the side of an expired horse in the middle of a dusty street. The picture was included in a newspaper's 2007 calendar and the response from readers prompted news articles. From there, it took off on the Internet....