Everyone knows the story: when Spanish conquistadors rode into the New World, Native Americans were stunned by a towering, four-legged creature they had never seen before. Horses, the theory goes, were a European import to the Americas.
But a new fossil DNA study indicates that horses actually originated in North America millions of years ago and only reached Europe thanks to an unexpected genetic middleman in China.
An extinct lineage called the Dalian horse, once dismissed as a local oddity in…