any of the nine species of Australian and Tasmanian marsupials constituting a subfamily Potoroinae, of the kangaroo family, Macropodidae (see kangaroo). Some authorities recognize a separate family, Potoroidae. They differ from other kangaroos in skull and urogenital anatomy and in having large canine teeth. All are rabbit-sized or smaller. Rat kangaroos live in undergrowth. At night they forage for grass, tubers, and underground fungi; some also eat grubs and worms.