Image of the Week #67, November 6th, 2012: From: Giant flightless bats from the future by Darren Naish at Tetrapod Zoology. Source: After Man, by Dougal Dixon. Despite the fact that close to 20% of the world's extant mammal species are species of bats, none of them have developed flightlessness. Compare that to birds, where flightlessness has evolved numerous times on numerous continents throughout history. This tantalizing factoid is the inspiration behind Dougal Dixon's invention of numerous flightless bat species in his futuristic book After Man (Dixon 1981). The 1.5-meter tall predator, Manambulus perhorridus, is surely the most formidable of them all. For more of Dixon's creations and a hypothesis on what is keeping bats in flight, read Tetrapod Zoology's post, "Giant flightless bats from the future."