The night stalker's powerful front legs are developed from the wings of its ancestors. Its back feet, which were originally used for grasping and clutching, now come over its shoulders and effectively form hands.
The Night Stalker, Manambulus perhorridus, is a large, ferocious, pack-hunting, flightless leaf-nosed bat from Batavia, from After Man: A Zoology of the Future.
Once other vertebrates had established themselves on the islands, a new family of ground-dwelling predatory bats arose. These creatures walk on their front legs (on what would, in the case of a flying bat, be its wings, the site of most of its locomotors muscles). Their hind legs and feet are still used for grasping, but now fall forward to hang down below their chin. As the bats locate their prey purely by echolocation, their ears and nose flaps have developed at the expense of their eyes, which are now atrophied.
The largest and most fearsome of these creatures is the night stalker. One and a half meters tall, it roams screeching and screaming through the Batavian forests at night in packs. They prey indiscriminately on other mammals and reptiles, attacking them with their ferocious teeth and claws.