Not all tree-living animals are active jumpers. Up in the topmost branches of the Eucalyptus trees of the southeastern and southwestern corners of the Australian continent lives a silvery blob, about 70 centimeters (2 feet) long. This is the tubb, a clumsy-looking creature moving sluggishly up and down the silvery grey branches of the Eucalyptus trees, feeding on nothing but the bluish foliage. At first glance it is difficult to imagine that both the tubb and the crackbeak are evolved from the same ancestor, Fulgurotherium, yet there are clues. The hind feet have four toes, the first of which point backwards and allow the animal to grasp branches. The hands have five fingers, the outer two of which are opposable. The deep head has powerful jaw muscles and a sharp beak, for breaking off foo