The animal on the cover of Erlang Programming is a brush-tailed rat kangaroo (Bettongia penicillata). The brush-tailed rat kangaroo is a small mammal found in western and southern Australia. It is a cross between a rat and a small wallaby, and although some of its features are reminiscent of a rat, it is not a rodent and is instead classified as a marsupial. In south Australia, they are found in semi-arid scrublands and grasslands; in western Australia, they prefer eucalyptus forests containing a vegetative layer of tussock grass, low woody scrub, and occasional bare patches of ground. They once inhabited more than 60% of the Australian mainland, but now they inhabit less than 1%.
Brush-tailed rat kangaroos have an unusual mammalian diet that consists of bulbs, tubers, seeds, insects, resins, and underground fungi; they do not drink water or eat green plants. Although fungi are not considered a good food source for mammals in general, they provide the nutrients necessary for the brush-tailed rat-kangaroo’s health.
The kangaroos’ coats are yellowish-gray in color, their feet are pale brown and have hairs that bristle, and their long tails have a prominent black crest. Their tails are also useful: brush-tailed rat kangaroos are able to curl their tails to carry bundles of material to build their nests. They are relatively slow-moving creatures, but are able to hop away quickly when disturbed.
Brush-tailed rat kangaroos are extremely nocturnal. During the day they rest in well-constructed, ...