Research reveals that a 20-million-year-old African fossil, long thought to be a bat, actually represents one of the earliest branches of the lemur family tree. The reassessment challenges a long-held view that lemurs descended from ancestors that colonized Madagascar in a single wave roughly 60 million years ago, and were the first mammals to get there. Instead, the researchers say two separate lemur lineages may have arrived independently, and much later than previously thought.